Attachment H - Stormwater Report - February 2018.pdf
Stormwater Report
Notice of Intent (NOI)
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
MassDOT Project No. 604597
February 2018
Prepared for:
MassDOT—Highway Division
10 Park Plaza
Boston, MA 02116
Prepared by:
Michael J. Rieger, PE
TranSystems
101 Arch Street, Suite 301
Boston, MA 02110
TABLE OF CONTENTS
GENERAL PROJECT DESCRIPTION ................................................................................................................... 2
RECEIVING WATER BODY ................................................................................................................................... 3
EXISTING CONDITIONS....................................................................................................................................... 3
PROPOSED IMPROVEMENTS ............................................................................................................................... 4
COMPLIANCE WITH THE TEN STORMWATER MANAGEMENT STANDARDS ............................... 6
Standard 1- No New Untreated Discharges .................................................................................................. 6
Standard 2- Peak Rate Attenuation ................................................................................................................... 6
Standard 3- Groundwater Recharge ................................................................................................................. 8
Standard 4- TSS Removal and Long-Term Pollution Prevention Plan ...................................................... 9
Standard 5- Higher Potential Pollutant Loads ............................................................................................... 11
Standard 6- Critical Areas ................................................................................................................................. 11
Standard 7- Redevelopment .............................................................................................................................. 11
Standard 8- Construction Period Pollution Prevention and Erosion Control Plan ............................. 11
Standard 9- Operation and Maintenance Plan .............................................................................................. 11
Standard 10- Illicit Discharge Prevention ....................................................................................................... 12
Attachment A- Checklist for Stormwater Report ........................................................................ A-1 - A-8
Attachment B- NRCS Soil Survey....................................................................................................... B-1 - B-4
Attachment C- Existing and Proposed Catchment Maps ........................................................... C-1 - C-2
Attachment D- Splash Pad Sizing Calculations ......................................................................................... D-1
Attachment E- BMP Calculations ........................................................................................................ E-1 - E-3
Attachment F- Peak Rate Attenuation Modeling Output ........................................................... F-1 - F-99
Attachment G- Test Pit Logs ............................................................................................................. G-1 - G-8
Attachment H- Long Term Pollution Prevention Plan (LTPPP) ................................................ H-1 - H-4
Attachment I- Operation and Maintenance Plan (O&M Plan) ........................................................ I-1 - I-2
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Northampton, MA
GENERAL PROJECT DESCRIPTION
The Massachusetts Department of Transportation – Highway Division (MassDOT) is proposing
improvements to the intersection of Route 9 (Bridge Street) and Damon Road in the city of
Northampton (Project). The Project evolved from a regional transportation study that evaluated the
potential need for an additional bridge over the Connecticut River. The study determined that no
additional bridge is required, but instead recommended improved traffic operations at Interchange
19 of I-91. The Project is located just west of the Calvin Coolidge Memorial Bridge spanning the
Connecticut River. It includes the intersection of Bridge Street and Damon Road/I-91 northbound
(NB) off-ramp, and the intersection of Bridge Street and the I-91 southbound (SB) on-ramp. Figure 1
shows the project locus map.
Figure 1 Locus Map
The designed improvements include reconstruction of the intersection of Route 9 with the NB off-
ramp and Damon Road as a two-lane roundabout with a 10-foot wide shared-use path. The SB on-
ramp will be widened to two lanes prior to the merge with I-91. Both the NB off-ramp and the SB
on-ramp will be lengthened to accommodate longer deceleration and acceleration lanes. The
proposed stormwater management design includes two Best Management Practices (BMPs), which
PROJECT LOCATION
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Northampton, MA
are both infiltration basins. These infiltration basins will be located between the NB off-ramp and I-
91 and the SB on-ramp and I-91, respectively. Access for maintenance will be from Route 9. The
proposed stormwater BMPs are described in more detail in the Proposed Improvements section of
this report. Descriptions of how the Project complies with the Massachusetts Stormwater
Standards are included in the section titled, Compliance with the Ten Stormwater Management
Standards. Attachment A includes a stamped and signed Massachusetts Department of
Environmental Protection Checklist for Stormwater Report.
RECEIVING WATER BODY
The Connecticut River flows from north to south, east of the Project site, and is listed in the
Massachusetts Year 2012 Integrated List of Waters as impaired for Escherichia coli and PCB in Fish
Tissue. No Total Maximum Daily Loads (TMDLs) have been reported to the United States
Environmental Protection Agency (US EPA) by the Massachusetts Department of Environmental
Protection (MassDEP) for the Connecticut River watershed. Stormwater from the project site
enters the river via closed drainage systems.
EXISTING CONDITIONS
I-91 is the primary north-south thoroughfare through western New England beginning in New
Haven, Connecticut at I-95 and terminating at the Canadian border in Derby Line, Vermont. The
divided, limited-access highway generally follows the Connecticut River and has two lanes in each
direction. Route 9, which runs in the east-west direction through Northampton, is a two-lane
roadway that widens to four lanes plus turning lanes through the signalized intersection with I-91.
Route 9 is a primary access route to the main campus of the University of Massachusetts at
Amherst. The Calvin Coolidge Bridge carries Route 9 over the Connecticut River into Hadley, MA.
The Norwottuck Rail Trail also crosses the Connecticut River just north of the project site. Damon
Road runs parallel to I-91, on the north side of Route 9, between I-91 and the Connecticut River.
Commercial properties occupy the west side of Damon Road near its intersection with Route 9.
The Elwell Recreation Area of the Connecticut River Greenway State Park lies on the east side of
Damon Road, along the western bank of the Connecticut River. A residential neighborhood of single
family houses populates the area west and northwest of the project site. Agricultural land occupies
both sides of I-91 on the south side of Exit 19. The project site within the limit of proposed work is
currently 45% impervious.
I-91 crosses over Route 9 with a high point in the profile just north of the project site. Route 9
generally rises to the east towards the Calvin Coolidge Bridge. On the west side of I-91, the
neighborhood north of the project site gradually rises higher than Route 9. On the east side of I-91,
the commercial properties and parkland gradually drop lower than Route 9. South of Route 9, the
topography drops about ten feet at roughly a 15 percent grade on both sides of I-91, before
reaching relatively flat agricultural land. One catch basin on the I-91 off-ramp and the infield area
between the I-91 off-ramp and I-91discharge runoff into the woods west of the I-91 off ramp (an 18”
culvert crosses under the off-ramp). All other runoff from the site is collected by an existing closed
drainage network that discharges to the Connecticut River, through either a 24-inch outfall 25 feet
south of the Calvin Coolidge Bridge, a 30-inch outfall 80 feet south of the Calvin Coolidge Bridge, or
an 18-inch outfall 45 feet south of the bridge for the Norwottuck Rail Trail.
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Attachment B includes a Hydrologic Soil Group (HSG) Web Soil Survey from the National Resource
Conservation Service (NRCS) that summarizes the area coverage for each soil type. Although a
portion of the site has no HSG available, the HSG can be assumed to match the surrounding soil
types, which is Hydrologic Soil Group B. Therefore, all soils within the limit of work of the Project
are classified as Hydrologic Soil Group B for the purposes of this stormwater report. Attachment C
shows an existing catchment map, with labels for total area, weighted average curve number (CN)
and time of concentration. The CN values used for existing conditions are taken from Exhibit 8-18
from the 2006 MassDOT design guide. The value used for woods along I-91 is 55 (Good condition).
The value used for grass throughout the site is 61 (Good condition). The value used for impervious
area is 98. All catchment areas have times of concentration less than the minimum five minutes.
Runoff from most of Route 9 and both barrels of I-91 north of Route 9 is designated as Catchment
A and discharges to the 24-inch outfall. The infield area between I-91 and the NB off-ramp is
Catchment B. The lower ends of the NB off-ramp and SB on-ramp, plus both barrels of I-91 south of
Route 9, form Catchment C. Runoff from the middle section of the NB off-ramp is designated as
Catchment D. The north end of the NB off-ramp and the eastbound side of Route 9 to the Calvin
Coolidge Bridge is Catchment E. Catchment G includes both barrels of I-91, south of the ramp
gores. These catchments combine and discharge to the 30-inch outfall.
Catchment H represents Damon Road runoff that discharges to the 18-inch outfall south of the Rail
Trail.
Catchment K is the wooded area adjacent to NB off-ramp. Catchment F is the wooded area
adjacent to SB on-ramp and also includes runoff from one catch basin on the SB-on ramp and the
infield area between I-91 and the SB on-ramp (which also receives flow from one catch basin located
on I-91 SB).
PROPOSED IMPROVEMENTS
The Project proposes the following improvements over existing conditions:
Deep sump catch basins
Forebays with Infiltration basins (Infiltration Basin B and Infiltration Basin J)
All runoff is captured by deep sump catch basins, which improve upon existing conditions by
removing more suspended solids and debris than existing standard catch basins.
The proposed closed drainage system is designed to adhere to the MassDOT design guide including
criteria for spread (ponding) at inlets, pipe sizing, and hydraulic grade line calculations. Calculations
for the closed drainage system will be included with the 100% design submittal.
Infiltration Basin B, proposed in the infield area between I-91 and the I-91 NB off-ramp, includes a
forebay for pretreatment removal of debris. From the wetland forebay, runoff spills over a stone
weir to a flat depression that is loamed and seeded to allow for infiltration. The basin holds and
infiltrates the required water quality and recharge volumes. An outlet control structure with a 12
inch orifice and grate is proposed to mitigate peak flow rates during the 2 and 10 year storm events.
The volume of storage below the orifice is the calculated recharge volume, and will drawdown
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within 72 hours. The outlet control structure allows the basin to have a minimum of one foot of
freeboard during the 100 year storm event.
Infiltration Basin J, proposed in the infield area between I-91 and the I-91 SB on-ramp, includes a
forebay for pretreatment removal of debris. From the wetland forebay, runoff spills over a stone
weir to a flat depression that is loamed and seeded to allow for infiltration. The basin holds and
infiltrates the required water quality and recharge volumes. In addition the basin holds the 2 year
storm. An overflow stone weir is proposed to mitigate the 10 and 100 year storm events. The
volume of storage below the weir elevation is the calculated recharge volume, and will drawdown
within 72 hours.
Attachment C shows a proposed catchment map, with labels for total area, weighted average curve
number and time of concentration. The method for estimating runoff rates within the proposed
catchments uses the same parameters as those used for existing conditions, with the exception that
for the proposed conditions, the existing woods along I-91 are proposed to be cleared and grubbed.
The existing 2:1 (H:V) side slopes will be loamed and seeded to allow for permanent erosion control
and slope stabilization. These slopes are categorized as Grass with a CN value of 61. The proposed
outside edges of the re-aligned 91 NB off-ramp and SB on-ramp will be Mechanically Stabilized Earth
(MSE) which yields a 1:1 slope. The slope will grow brush over time. The CN value used is 48, which
is categorized as brush-weed-grass mixture with brush the major element (good cover). These walls
are proposed to allow for flood storage at the bottom of the slope. The bottom of the slopes are
categorized as Woods – grass combination with good cover, which has a CN value of 58.
Runoff from most of Route 9 and both barrels of I-91 north of Route 9 continues to discharge to
the 24-inch outfall as Catchment A, while Catchment J represents the north end of the SB on-ramp
that discharges to the proposed Infiltration Basin J. The infield area between I-91 and the SB
on-ramp that is not occupied by the infiltration basin remains designated as a part of Catchment F.
Likewise, the Damon Road runoff remains designated as Catchment H. The proposed condition
reduces the sizes of Catchment A, Catchment F, and Catchment H, as compared to their existing
condition counterparts.
Catchment F and Catchment K discharge adjacent to SB on-ramp and NB off-ramp, respectively.
The respective areas each decrease in size from existing conditions, and the peak flow rates are
mitigated by replacing the existing woods with MSE walls which will fill out with brush once
permanent erosion stabilization is established.
All remaining catchment areas still discharge to the 30-inch outfall. Although the combined area of
the remaining proposed catchment areas is larger than existing conditions, extended detention
storage is included within the Infiltration Basin B area to mitigate peak flow rates. The majority of
the proposed roundabout and both sides of Route 9 east of the roundabout are added to
Catchment B, which discharges to the infiltration basin. Catchment B includes the area previously
designated as existing Catchment E, therefore the proposed condition has no proposed Catchment
E. The middle section of the NB off-ramp remains designated as Catchment D, and is slightly smaller
than the existing Catchment D. The proposed Catchment C and Catchment G are moderately
expanded in size, due to the roadway geometry that is required for the designed traffic and safety
improvements.
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COMPLIANCE WITH THE TEN STORMWATER MANAGEMENT
STANDARDS
The following low impact design (LID) measures are employed for this Project.
No disturbance to any wetland resource areas
Two infiltration basins with sediment forebays
Minimizing disturbance to existing trees and shrubs
The proposed stormwater management design complies with the ten Massachusetts
Stormwater Standards.
Standard 1- No New Untreated Discharges
This standard requires that the design provide water quality treatment to all proposed
stormwater discharges, which improves the water quality of downstream receiving water
bodies. The proposed stormwater management design meets the requirements of
Standard 1.
All stormwater runoff directed to existing outfalls is treated prior to passage offsite. The different
levels of treatment are described in more detail in the description of compliance with Standard 4.
The Project does not add any untreated discharges, because no new outfalls are proposed by this
project. One outfall entering Catchment F from I-91 is being re-directed in order for Infiltration
Basin J to be constructed. See Attachment D for splash pad calculations.
Standard 2- Peak Rate Attenuation
This standard requires that the design minimize the downstream impacts of peak flow
rates during storm events by detaining stormwater onsite.
The project reduces post construction peak runoff rates to below preconstruction peak runoff rates
during the 2-year, 10-year, and 100-year storm events for project discharge points.
The peak rate of runoff is a measure of how rapidly stormwater flows from a catchment area during
specific storm events. Peak rates of runoff are reduced by detaining runoff during storm events and
releasing the stormwater gradually as the storms subside. Massachusetts Stormwater Management
Standard Number 2 requires that the post-construction discharge from a project match the
discharge prior to construction, during the 2-year 24-hour and 10-year 24-hour Type III storm
events. Standard 2 also requires that the project identify whether or not peak discharges from the
100-year 24-hour Type III storm increase off-site flooding. If increased flooding is found, then the
project must attenuate peak flow from the 100-year storm event.
Bentley PondPack V8i pond routing software was employed using the Unit Hydrograph method to
route runoff hydrographs through flood storage facilities and to their outlets, compute the peak
discharges through outlets, and determine the maximum high water elevation during storm events.
This method calculates runoff rate using time of concentration, curve number, catchment acreage,
and 24-hr precipitation for the selected return period and rainfall distribution. Rainfall data for the
storm events were estimated from the Massachusetts Rainfall Data Maps derived from Technical
Paper 40 (1961) and included as Appendix F-1 in the March 2002 Hydrology Handbook for
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Conservation Commissioners. The analysis uses 3.0 inches for the 2-year Type III 24-hour storm
event, 4.5 inches for the 10-year, and 6.4 inches for the 100-year Type III 24-hour storm event.
Curve numbers represent the relative permeability of local soil types, with 98 equal to the most
impermeable pavement surfaces. Permeable areas are assigned curve numbers according to the
hydrologic code of the soil type (A, B, C, or D) and whether it supports enough tree growth to
qualify as woods or is covered with grass. As stated previously, all CN values are associated with
hydrologic code B for this project.
Times of concentration demonstrate the longest time that it takes runoff to drain from any point in
a catchment area to the lowest point. Depending on the characteristics of the flow path, the time of
concentration calculation will include some combination of sheet flow, shallow concentrated flow,
flow in a pipe, or channel flow. Sheet flow lengths are limited to a maximum 50 feet. Flow in a pipe
is conservatively estimated based on the length traveled times an assumed minimum velocity of 3
feet per second, since the project site is very flat. Other characteristics that define the time of
concentration, such as slope, length, and Manning’s n are selected based on the actual conditions
estimated along the flow path identified. Manning’s n values are selected in accordance with “Table
3-1 Roughness Coefficients (Manning’s n) For Sheet Flow” in 210-VI-TR-55, Second Ed., June 1986,
with runoff over pavement, grass, and woods assigned a Manning’s roughness coefficient of 0.01,
0.15, and 0.40, respectively. The minimum time of concentration is five minutes, or 0.083 hours. All
existing and proposed catchment areas within the project are found to have times of concentration
less than the minimum five minutes.
The project has a variety of design points within the project boundaries, however the five primary
discharge points are the following:
DP – A, a 24” outfall to the Connecticut River
DP – H, an 18” outfall to the Connecticut River
30” outfall to the Connecticut River
DP – F, west side adjacent to Interstate 91 SB on-ramp
DP – K, east side adjacent to Interstate 91 NB off-ramp
As shown in Table 1, the hydrologic model compares post construction runoff rates to
preconstruction runoff rates for three different storm events at ten design points. Although flows
increase at design points B, C, and G due to the required widening and lengthening of the I-91 on
and off ramps, the design points discharging adjacent to the project and the Connecticut River are
mitigated by the proposed infiltration basins and reduction in area. To accommodate the added flow
generated from catchments B, C and G during a 10 Year storm, an existing 24” pipe will be upsized
to a 30” pipe to handle the added flow.
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Northampton, MA
Table 1
Post-construction Runoff Rates Reduced to Below Pre-construction Rates
2-Year (CFS) 10-Year (CFS) 100-Year (CFS)
Design Point PRE POST PRE POST PRE POST
DP-A (24” Outfall) 6.66 5.01 11.59 8.84 17.85 13.75
DP-B 0.43 0.23 1.61 2.42 3.51 4.67
DP-C 3.68 3.70 6.71 7.00 10.65 11.32
DP-D 0.44 0.34 0.66 0.52 0.94 0.74
DP-E 1.79 0.00 2.73 0.00 3.91 0.00
DP-F (West of SB off-ramp) 0.77 0.67 3.58 2.52 8.23 5.49
DP-G 7.68 9.03 14.26 16.47 22.84 26.12
DP-H (18” Outfall) 1.81 1.47 2.85 2.38 4.15 3.51
DP-K (East of NB on-ramp) 0.19 0.18 1.68 1.39 4.63 3.68
30” Outfall 13.67 12.79 25.51 24.24 31.33 31.33
Attachment C shows the existing and proposed catchment maps. These maps are intended to show
how the existing areas within a catchment change based on the proposed project (I.E. EX-A in
existing is PR-A in proposed). These catchments are also shown in Attachment F, which shows the
modeling analysis for existing and proposed conditions during each storm event.
The outlet from Infiltration Basin B discharges to a closed drainage network that is well above the
elevation of the river, so it is modeled as a free outfall tailwater condition. The infiltration basin
holds the 100-year storm event with 15 inches of freeboard. Storms larger than the 100-year storm
event overflow into the grate of the outlet control structure. Infiltration basin J holds the 100-year
storm event with 13 inches of freeboard. Storms larger than the 100-year storm event overflow
over the stone weir and water flows to the area adjacent to SB on-ramp via an existing 18” culvert.
Standard 3- Groundwater Recharge
This standard requires that the design encourage stormwater to infiltrate the ground to
recharge groundwater. The proposed stormwater management design meets the
requirements of Standard 3 to the maximum extent practicable.
The recharge volume required to fully meet Standard 3 is equivalent to the recharge volume
currently provided by existing soils that are covered by proposed impervious surfaces, minus the
recharge volume that will be provided by removing existing paved surfaces. Attachment E includes
the Water Quality and Recharge Summary, which provides a detailed calculation of the Required
Recharge Volume. Since all soils within the project limit are classified as HSG B, the Required
Recharge Volume is equivalent to the added 41,632 square feet of impervious area, multiplied by
0.35 inches, based on Table 2.3.2. Recharge Target Depth by Hydrologic Soil Group from Volume 3:
Documenting Compliance with the Massachusetts Stormwater Management Standards of the
Massachusetts Stormwater Handbook. The resulting Required Recharge Volume is 1,214 cubic feet.
The proposed design exceeds the minimum Required Recharge Volume by providing 11,853 cubic
feet of infiltration volume between each of the proposed infiltration basins. Test pits were
conducted in the vicinity of the proposed infiltration basins. Test Pits 1-4 (TP-1, TP-2, TP-3, TP-4)
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are included in Attachment G. Infiltration Basin J has a proposed bottom elevation of 123. Based on
TP-1 and TP-2 the existing soil layer at elevation 123 is loamy sand. The saturated hydraulic
conductivity for loamy sand from the Rawls Table is 2.41 inches per hour. The resulting drawdown
calculation for the basin is 22 hours, which is less than the required 72 hour minimum. Infiltration
Basin B has a proposed bottom elevation of 130. Based on TP-3 and TP-4 the existing soil layer at
elevation 130 is sandy loam. The saturated hydraulic conductivity for sandy loam from the Rawls
Table is 1.02 inches per hour. The resulting drawdown calculation for the basin is 57 hours, which is
less than the required 72 hour minimum. It should be noted that there is a layer of loam (based on
TP-4) that is 4.8 feet deep (elevation 130.0 and 129.2) that will need to be excavated. Prior to filling
with 8 inches of loam borrow, the native sandy loam is required to be tilled to a depth of 18 inches.
Capture area adjustment calculations are not provided to quantify the adjusted minimum storage
volume because meeting that design goal for a project of this size and linear character is not
practicable.
Standard 4- TSS Removal and Long-Term Pollution Prevention Plan
This standard requires that the stormwater design include features to remove sediment
from the first flush of runoff, as well as a long-term pollution prevention plan that identifies
feasible ways to minimize erosion and the release of sediment over the full operational life
of the design. The proposed stormwater management design meets the requirements of
Standard 4 to the maximum extent practicable.
A long-term pollution prevention plan is included as Attachment H.
Percent impervious is increased from 45% to 50% for the project. The proposed design includes
deep sump catch basins, and two infiltration basins each with a sediment forebay. Deep sump catch
basins (DSCB) provide 25% Total Suspended Solids (TSS) removal, and the infiltration basins (IB)
with forebays each provide 80% TSS removal. As shown in Table 2 below, the proposed design
includes two potential treatment trains. Type A provides 85% TSS removal and Type B provides
25% TSS removal.
Table 2- Percent TSS Removal
Treatment Train Type A Treatment Train
Type B
DSCB 25% 0.75 DSCB 25% 0.75
IB 80% 0.15
Removal 85% 25%
Contributing Impervious 2.08 ac. 7.25 ac.
The contributing impervious area of 2.08 acres shown for Treatment Train Type A is the sum of
1.70 acres entering into Infiltration Basin B and 0.38 acres entering into Infiltration Basin J. The
contributing impervious area of 7.25 acres includes all catchment areas that will flow into deep sump
catch basins and directly into the existing drainage system that will not enter a proposed BMP. The
estimated TSS% removal provided by the treatment trains is shown in the following calculation.
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Estimated TSS% Removal = (2.08 ac.* 85% + 7.25 ac.* 25% + 0.79 ac. * 0%) / (10.12 ac.) = 35.4%
The Design TSS% (Minimum) is based on the new (increased) impervious area for the project site.
This area is calculated by the area of redevelopment impervious (total proposed impervious area)
on site (10.12 acres) and subtracting the existing total impervious area on the site (9.16 acres),
yielding 0.96 acres of new impervious.
Design TSS% (Minimum) = (Area of New Impervious) x (80%) /
((Area of New Impervious) + Area of Redevelopment Impervious))
Design TSS% (Minimum) = (0.96 ac. * 80%) / (0.96 ac. + 10.12 ac.) = 6.9%
The estimated TSS% removal of 35.4% is greater than the minimum requirement of 6.9%.
The proposed Infiltration Basin J and Infiltration Basin B are designed to treat the required water
quality volume (WQV), as shown in the BMP Calculations Water Quality and Recharge Summary
included in Attachment E. The required WQV for each forebay is equivalent to one-tenth inch of
rainfall over the contributing impervious drainage area. The required WQV for Infiltration Basin J is
equivalent to one inch of rainfall over the contributing impervious drainage area since the layer of
infiltration happens in loamy sand having a saturated hydraulic conductivity of 2.41 inches per hour,
which is considered a rapid infiltration rate (over 2.40 inches per hour). The required WQV for
Infiltration Basin B is equivalent to one-half inch of rainfall over the contributing impervious drainage
area since the layer of infiltration happens in sandy loam having a saturated hydraulic conductivity of
1.02 inches per hour, which is not a rapid infiltration rate. Table 3 presents the contributing
impervious areas for each treatment Best Management Practice (BMP), calculates the required
WQV for each, and includes the water quality volume provided by each BMP. The water quality
volume provided is equivalent to the volume of stormwater that is held below the lowest invert out
of the basins. The provided WQV exceeds the required WQV in each case.
Table 3- Required Water Quality Volumes
Treatment BMP
Sensitivity
Depth
(in.)
Contributing
Impervious
Area
(sf)
Required
WQV
(cf)
Provided
WQV
(cf)
Forebay for Infiltration Basin B 0.1 73,887 616 875
Infiltration Basin B 0.5 73,887 3,079 7,246
Forebay for Infiltration Basin J 0.1 16,720 140 270
Infiltration Basin J 1.0 16,720 1,394 4,607
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Standard 5- Higher Potential Pollutant Loads
This standard requires that the design remove more sediment from land uses with higher
potential for pollutant loads such as high traffic parking lots. The proposed stormwater
management design meets the requirements of Standard 5.
The drainage system collects stormwater only from land used for vehicle and pedestrian traffic,
which does not constitute a land use with higher potential pollutant loads.
Standard 6- Critical Areas
This standard requires that the design provide additional protection to sensitive areas such
as public water supplies. The proposed stormwater management design meets the
requirements of Standard 6.
None of the Project’s outfalls discharge to a Zone II, Interim Wellhead Protection Area,
Outstanding Resource Water, shellfish growing area, bathing beach, or cold-water fishery.
Standard 7- Redevelopment
This standard is included by MA DEP to allow projects within already developed areas more
flexibility to improve upon existing conditions and meet some standards only to the
maximum extent practicable (MEP).
Because this Project corrects substandard intersections, it qualifies as a redevelopment project and
meets Standards 2, 3, and 4 to the maximum extent practicable.
Standard 8- Construction Period Pollution Prevention and Erosion Control
Plan
This standard requires that the design control the movement of sediment during
construction. The proposed stormwater management design meets the requirements of
Standard 8.
The implementation of erosion and sediment controls during construction is considered a standard
practice for MassDOT roadway projects. Prior to land disturbance, the contractor will prepare and
submit a complete Stormwater Pollution Prevention Plan (SWPPP) for meeting the standards and
requirements of the NPDES Construction General Permit.
Standard 9- Operation and Maintenance Plan
This standard requires that the design encourage proper long-term operation and
maintenance of the proposed drainage system. The proposed stormwater management
design meets the requirements of Standard 9.
An Operation and Maintenance Plan is included as Attachment I.
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Standard 10- Illicit Discharge Prevention
This standard requires that the design prevent illegal connections of non-stormwater
pollutant sources to the drainage system. The proposed stormwater management design
meets the requirements of Standard 10.
No illicit connections are known at the project site. If any such connections are discovered during
construction, the contractor will notify the applicant, who will implement appropriate enforcement
actions. An Illicit Discharge Compliance Statement will be submitted prior to the discharge of any
stormwater to post-construction BMPs.
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Northampton, MA
ATTACHMENT A-
MassDEP Checklist for Stormwater Report
Pages A-1 - A-8
604597 Northamption sw checklist • 04/01/08 Stormwater Report Checklist • Page 1 of 8
Massachusetts Department of Environmental Protection
Bureau of Resource Protection - Wetlands Program
Checklist for Stormwater Report
A. Introduction
Important: When
filling out forms
on the computer,
use only the tab
key to move your cursor - do not
use the return
key.
A Stormwater Report must be submitted with the Notice of Intent permit application to document
compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for
the Stormwater Report (which should provide more substantive and detailed information) but is offered
here as a tool to help the applicant organize their Stormwater Management documentation for their
Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist,
the Stormwater Report must contain the engineering computations and supporting information set forth in
Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and
certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth.
The Stormwater Report must include:
The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see
page 2) that certifies that the Stormwater Report contains all required submittals.1 This Checklist
is to be used as the cover for the completed Stormwater Report.
Applicant/Project Name
Project Address
Name of Firm and Registered Professional Engineer that prepared the Report
Long-Term Pollution Prevention Plan required by Standards 4-6
Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required
by Standard 82
Operation and Maintenance Plan required by Standard 9
In addition to all plans and supporting information, the Stormwater Report must include a brief narrative
describing stormwater management practices, including environmentally sensitive site design and LID
techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are
required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types,
critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site
where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for
both existing and proposed conditions at a scale that enables verification of supporting calculations.
As noted in the Checklist, the Stormwater Management Report shall document compliance with each of
the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The
soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the
Massachusetts Stormwater Handbook.
To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report
Checklist by checking the box to indicate that the specified information has been included in the
Stormwater Report. If any of the information specified in the checklist has not been submitted, the
applicant must provide an explanation. The completed Stormwater Report Checklist and Certification
must be submitted with the Stormwater Report.
1 The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report, the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to
the post-construction best management practices.
2 For some complex projects, it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in
the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the
project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan
before commencing any land disturbance activity on the site.
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604597 Northamption sw checklist • 04/01/08 Stormwater Report Checklist • Page 3 of 8
Massachusetts Department of Environmental Protection
Bureau of Resource Protection - Wetlands Program
Checklist for Stormwater Report
Checklist (continued)
LID Measures: Stormwater Standards require LID measures to be considered. Document what
environmentally sensitive design and LID Techniques were considered during the planning and design of
the project:
No disturbance to any Wetland Resource Areas
Site Design Practices (e.g. clustered development, reduced frontage setbacks)
Reduced Impervious Area (Redevelopment Only)
Minimizing disturbance to existing trees and shrubs
LID Site Design Credit Requested:
Credit 1
Credit 2
Credit 3
Use of “country drainage” versus curb and gutter conveyance and pipe
Bioretention Cells (includes Rain Gardens)
Constructed Stormwater Wetlands (includes Gravel Wetlands designs)
Treebox Filter
Water Quality Swale
Grass Channel
Green Roof
Other (describe): Two (2) Sediment Forebays with two (2) Infiltration Basins
Standard 1: No New Untreated Discharges
No new untreated discharges
Outlets have been designed so there is no erosion or scour to wetlands and waters of the
Commonwealth
Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included.
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604597 Northamption sw checklist • 04/01/08 Stormwater Report Checklist • Page 4 of 8
Massachusetts Department of Environmental Protection
Bureau of Resource Protection - Wetlands Program
Checklist for Stormwater Report
Checklist (continued)
Standard 2: Peak Rate Attenuation
Standard 2 waiver requested because the project is located in land subject to coastal storm flowage
and stormwater discharge is to a wetland subject to coastal flooding.
Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour
storm.
Calculations provided to show that post-development peak discharge rates do not exceed pre-
development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site
flooding increases during the 100-year 24-hour storm, calculations are also provided to show that
post-development peak discharge rates do not exceed pre-development rates for the 100-year 24-
hour storm.
Standard 3: Recharge
Soil Analysis provided.
Required Recharge Volume calculation provided.
Required Recharge volume reduced through use of the LID site Design Credits.
Sizing the infiltration, BMPs is based on the following method: Check the method used.
Static Simple Dynamic Dynamic Field1
Runoff from all impervious areas at the site discharging to the infiltration BMP.
Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations
are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to
generate the required recharge volume.
Recharge BMPs have been sized to infiltrate the Required Recharge Volume.
Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum
extent practicable for the following reason:
Site is comprised solely of C and D soils and/or bedrock at the land surface
M.G.L. c. 21E sites pursuant to 310 CMR 40.0000
Solid Waste Landfill pursuant to 310 CMR 19.000
Project is otherwise subject to Stormwater Management Standards only to the maximum extent
practicable.
Calculations showing that the infiltration BMPs will drain in 72 hours are provided.
Property includes a M.G.L. c. 21E site or a solid waste landfill and a mounding analysis is included.
1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used.
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604597 Northamption sw checklist • 04/01/08 Stormwater Report Checklist • Page 5 of 8
Massachusetts Department of Environmental Protection
Bureau of Resource Protection - Wetlands Program
Checklist for Stormwater Report
Checklist (continued)
Standard 3: Recharge (continued)
The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10-
year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding
analysis is provided.
Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland
resource areas.
Standard 4: Water Quality
The Long-Term Pollution Prevention Plan typically includes the following:
Good housekeeping practices;
Provisions for storing materials and waste products inside or under cover;
Vehicle washing controls;
Requirements for routine inspections and maintenance of stormwater BMPs;
Spill prevention and response plans;
Provisions for maintenance of lawns, gardens, and other landscaped areas;
Requirements for storage and use of fertilizers, herbicides, and pesticides;
Pet waste management provisions;
Provisions for operation and management of septic systems;
Provisions for solid waste management;
Snow disposal and plowing plans relative to Wetland Resource Areas;
Winter Road Salt and/or Sand Use and Storage restrictions;
Street sweeping schedules;
Provisions for prevention of illicit discharges to the stormwater management system;
Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the
event of a spill or discharges to or near critical areas or from LUHPPL;
Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan;
List of Emergency contacts for implementing Long-Term Pollution Prevention Plan.
A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an
attachment to the Wetlands Notice of Intent.
Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for
calculating the water quality volume are included, and discharge:
is within the Zone II or Interim Wellhead Protection Area
is near or to other critical areas
is within soils with a rapid infiltration rate (greater than 2.4 inches per hour)
involves runoff from land uses with higher potential pollutant loads.
The Required Water Quality Volume is reduced through use of the LID site Design Credits.
Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if
applicable, the 44% TSS removal pretreatment requirement, are provided.
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604597 Northamption sw checklist • 04/01/08 Stormwater Report Checklist • Page 6 of 8
Massachusetts Department of Environmental Protection
Bureau of Resource Protection - Wetlands Program
Checklist for Stormwater Report
Checklist (continued)
Standard 4: Water Quality (continued)
The BMP is sized (and calculations provided) based on:
The ½” or 1” Water Quality Volume or
The equivalent flow rate associated with the Water Quality Volume and documentation is
provided showing that the BMP treats the required water quality volume.
The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary
BMP and proposed TSS removal rate is provided. This documentation may be in the form of the
propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook
and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying
performance of the proprietary BMPs.
A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing
that the BMPs selected are consistent with the TMDL is provided.
Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs)
The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution
Prevention Plan (SWPPP) has been included with the Stormwater Report.
The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior
to the discharge of stormwater to the post-construction stormwater BMPs.
The NPDES Multi-Sector General Permit does not cover the land use.
LUHPPLs are located at the site and industry specific source control and pollution prevention
measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow
melt and runoff, and been included in the long term Pollution Prevention Plan.
All exposure has been eliminated.
All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list.
The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and
grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil
grit separator, a filtering bioretention area, a sand filter or equivalent.
Standard 6: Critical Areas
The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP
has approved for stormwater discharges to or near that particular class of critical area.
Critical areas and BMPs are identified in the Stormwater Report.
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604597 Northamption sw checklist • 04/01/08 Stormwater Report Checklist • Page 7 of 8
Massachusetts Department of Environmental Protection
Bureau of Resource Protection - Wetlands Program
Checklist for Stormwater Report
Checklist (continued)
Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum
extent practicable
The project is subject to the Stormwater Management Standards only to the maximum Extent
Practicable as a:
Limited Project
Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development
provided there is no discharge that may potentially affect a critical area.
Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development
with a discharge to a critical area
Marina and/or boatyard provided the hull painting, service and maintenance areas are protected
from exposure to rain, snow, snow melt and runoff
Bike Path and/or Foot Path
Redevelopment Project
Redevelopment portion of mix of new and redevelopment.
Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an
explanation of why these standards are not met is contained in the Stormwater Report.
The project involves redevelopment and a description of all measures that have been taken to
improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found
in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that
the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment
and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b)
improves existing conditions.
Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control
A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the
following information:
Narrative;
Construction Period Operation and Maintenance Plan;
Names of Persons or Entity Responsible for Plan Compliance;
Construction Period Pollution Prevention Measures;
Erosion and Sedimentation Control Plan Drawings;
Detail drawings and specifications for erosion control BMPs, including sizing calculations;
Vegetation Planning;
Site Development Plan;
Construction Sequencing Plan;
Sequencing of Erosion and Sedimentation Controls;
Operation and Maintenance of Erosion and Sedimentation Controls;
Inspection Schedule;
Maintenance Schedule;
Inspection and Maintenance Log Form.
A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing
the information set forth above has been included in the Stormwater Report.
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604597 Northamption sw checklist • 04/01/08 Stormwater Report Checklist • Page 8 of 8
Massachusetts Department of Environmental Protection
Bureau of Resource Protection - Wetlands Program
Checklist for Stormwater Report
Checklist (continued)
Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control
(continued)
The project is highly complex and information is included in the Stormwater Report that explains why
it is not possible to submit the Construction Period Pollution Prevention and Erosion and
Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and
Erosion and Sedimentation Control has not been included in the Stormwater Report but will be
submitted before land disturbance begins.
The project is not covered by a NPDES Construction General Permit.
The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the
Stormwater Report.
The project is covered by a NPDES Construction General Permit but no SWPPP been submitted.
The SWPPP will be submitted BEFORE land disturbance begins.
Standard 9: Operation and Maintenance Plan
The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and
includes the following information:
Name of the stormwater management system owners;
Party responsible for operation and maintenance;
Schedule for implementation of routine and non-routine maintenance tasks;
Plan showing the location of all stormwater BMPs maintenance access areas;
Description and delineation of public safety features;
Estimated operation and maintenance budget; and
Operation and Maintenance Log Form.
The responsible party is not the owner of the parcel where the BMP is located and the Stormwater
Report includes the following submissions:
A copy of the legal instrument (deed, homeowner’s association, utility trust or other legal entity)
that establishes the terms of and legal responsibility for the operation and maintenance of the
project site stormwater BMPs;
A plan and easement deed that allows site access for the legal entity to operate and maintain
BMP functions.
Standard 10: Prohibition of Illicit Discharges
The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges;
An Illicit Discharge Compliance Statement is attached;
NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of
any stormwater to post-construction BMPs.
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Stormwater Report
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
ATTACHMENT B-
NRCS Soil Survey
Pages B-1 - B-4
Hydrologic Soil Group—Hampshire County, Massachusetts, Central Part
(I-91 Northampton Hydrologic Soil Group)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/27/2015
Page 1 of 4
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695400 695500 695600 695700 695800 695900 696000 696100 696200 696300 696400 696500 696600 696700
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84
0 300 600 1200 1800
Feet
0 50 100 200 300
Meters
Map Scale: 1:6,480 if printed on A landscape (11" x 8.5") sheet.
B
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MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at 1:15,800.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil line
placement. The maps do not show the small areas of contrasting
soils that could have been shown at a more detailed scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more accurate
calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as of
the version date(s) listed below.
Soil Survey Area: Hampshire County, Massachusetts, Central
Part
Survey Area Data: Version 9, Sep 19, 2014
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
Date(s) aerial images were photographed: Mar 28, 2011—Apr 18,
2011
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor shifting
of map unit boundaries may be evident.
Hydrologic Soil Group—Hampshire County, Massachusetts, Central Part
(I-91 Northampton Hydrologic Soil Group)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/27/2015
Page 2 of 4
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Hydrologic Soil Group
Hydrologic Soil Group— Summary by Map Unit — Hampshire County, Massachusetts, Central Part (MA609)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
1 Water 34.6 16.2%
8A Limerick silt loam, 0 to 3
percent slopes
B/D 1.8 0.8%
30A Raynham silt loam, 0 to 3
percent slopes
C/D 0.0 0.0%
96A Hadley silt loam, 0 to 3
percent slopes
B 44.2 20.7%
98A Winooski silt loam, 0 to 3
percent slopes
B 43.7 20.4%
225A Belgrade silt loam, 0 to 3
percent slopes
C 29.1 13.6%
741A Amostown-Windsor silty
substratum-Urban
land complex, 0 to 3
percent slopes
50.2 23.5%
744A Hadley-Winooski-Urban
land complex, 0 to 3
percent slopes
B 10.0 4.7%
Totals for Area of Interest 213.5 100.0%
Hydrologic Soil Group—Hampshire County, Massachusetts, Central Part I-91 Northampton Hydrologic Soil
Group
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/27/2015
Page 3 of 4
B - 3
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive precipitation
from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly
wet. These consist mainly of deep, well drained to excessively drained sands or
gravelly sands. These soils have a high rate of water transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well drained
soils that have moderately fine texture to moderately coarse texture. These soils
have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of water
transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay layer
at or near the surface, and soils that are shallow over nearly impervious material.
These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in their
natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Hampshire County, Massachusetts, Central Part I-91 Northampton Hydrologic Soil
Group
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/27/2015
Page 4 of 4
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Stormwater Report
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
ATTACHMENT C-
Existing and Proposed Catchment Maps
Pages C-1 - C-2
I-91
30" OUTFALL
24" OUTFALL
18" OUTFALL
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EXISTING CATCHMENTS
NAME DP
AREA (SF)CURVE
NUMBERTc (MIN)IMPERVIOUS GRASS WOODS TOTAL
EX-A A 113,768 33,902 13,512 161,182 87 5.0
EX-B B 3,940 48,910 9,354 62,204 62 5.0
EX-C C 63,951 37,201 0 101,152 84 5.0
EX-D D 7,609 0 0 7,609 98 5.0
EX-E E 30,813 910 0 31,723 97 5.0
EX-F F 14,448 34,483 109,887 158,818 60 5.0
EX-G G 133,678 87,395 0 221,073 83 5.0
EX-H H 30,976 3,398 0 34,374 94 5.0
EX-K K 0 6,365 108,236 114,601 55 5.0
LEGEND
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FED. AID PROJ. NO.SHEET
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SHEETS
NORTHAMPTON
I-91 INTERCHANGE 19
STATE
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PROJECT FILE NO.
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EXISTING CATCHMENT MAP
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C03 DMH
G01 REMODEL DMH
REPLACE EXIST 24" RCP
WITH 30" RCP
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PROPOSED CATCHMENTS
NAME DP
AREA (SF)CURVE
NUMBERTc (MIN)IMPERVIOUS GRASS WOODS GRASS-WOODSBRUSH TOTAL
PR-A A 84,893 38,361 2,908 0 0 126,162 86 5.0
PR-B Pond B 73,887 32,888 0 0 0 106,775 87 5.0
Pond B B 0 35,471 0 0 0 35,471 61 5.0
PR-C C 62,438 49,310 0 0 0 111,748 82 5.0
PR-D D 5,956 0 0 0 0 5,956 98 5.0
PR-F F 13,969 27,100 0 31,205 24,916 97,190 62 5.0
PR-G G 154,965 93,199 0 0 0 248,164 84 5.0
PR-H H 25,013 4,685 0 0 0 29,698 92 5.0
PR-J Pond J 16,720 4,224 0 0 0 20,944 91 5.0
Pond J F 0 21,547 0 0 0 21,547 61 5.0
PR-K K 2,974 0 0 54,713 28,655 86,342 56 5.0
LEGEND
PR-A
PR-C
PR-F
PR-H
PR-K
GRASS
PR-B
PR-D
PR-G
PR-J
BRUSH
WOODS
GRASS - WOODS
PROPOSED DRAINAGE
EXISTING DRAINAGE
DP-A
DISCHARGE POINT FOR PR-A
FED. AID PROJ. NO.SHEET
NO.
TOTAL
SHEETS
NORTHAMPTON
I-91 INTERCHANGE 19
STATE
MA
PROJECT FILE NO.
-
604597
60
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SCALE: 1" = 100'
0 200 300 400
N
PROPOSED CATCHMENT MAP
22
C - 2
Stormwater Report
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
ATTACHMENT D-
Splash Pad Sizing Calculations
Page D1
604597 - Improvements on I-91 Interchange 19 at Route 9 and Damon Road
Northampton, MA
NOI Submittal
Splash Pad Sizing Calculations 2/27/2018
By: MJR
Checked by: RWH
Splash Pad Sizing:
Objective:
To determine the size of the rip rap apron at then end of a flared end section to prevent scour or erosion.
Riprap Size: D50 (in.)
Apron Length: L (ft.)
Apron Depth: H (ft.)
Arpon Width: W (ft.)
Known Information:
Pipe Diameter: D (ft.)
Design Discharge: Q (cfs)2.65 Specific Weight of Rock
Actual Tailwater Depth: TWa (ft.)62.43 lb/ft^3 Unit Weight of Water
Acceleration due to gravity, 32.2: g (ft/s^2)
Table 10.1. Example Riprap Classes and Apron Dimensions
Class D50
(in.)
Apron Length (ft.)Apron
Depth (in.)
Weight (lb)
1 5 4D 3.5D50 12
2 6 4D 3.3D50 21
3 10 5D 2.4D50 96 M2.02.3 Stone fo Pipe Ends
4 14 6D 2.2D50 263
5 20 7D 2.0D50 766
6 22 8D 2.0D50 1019
Methodology:
U.S. Federal Highway Administration, 2006, Hydraulic Design of Energy Dissipators for Culverts and Channels,
Hydraulic Engineering Center Circular No. 14
Tailwater Check:
Tailwater Depth should be limited to between 0.4D and 1.0D. If Tailwater is unknown, use 0.4D.
Therefore, if TWa < 0.4D; use TWu = 0.4D
if TWa > D; TWu = D
*Tailwater Depth to be used for Equation purposes, TWu
Calculations:
Use Equation (10.4) to determine rip rap size from Chapter 10 in HEC 14.
LOCATION OUTFALL Pipe Dia.Design Discharge Tailwater Invert Actual TW Depth TW Depth Riprap Size Riprap Size Rip Rap Length Depth Width
D Q Elev.Elev.TWa TWu D50 D50 Table Class L D W
(ft.)(cfs)(ft)(ft)(ft)(ft)(in.)(in.)(ft.)(in.)(ft.)
Example:HEC 14 5.00 85.00 943.23 941.23 0.00 2.0 5.2 6.0 2 20 20 28
Northampton F05 12 FES 1.00 1.17 122.40 122.00 0.00 0.4 0.7 5.0 1 4 18 6
Northampton J51 12 FES 1.00 2.49 129.40 129.00 0.00 0.4 2.0 5.0 1 4 18 6
Note: Apron will consist of M2. 02.4 Modified Rockfill
Apron DimensionsDesign Criteria
D
-
1
Stormwater Report
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
ATTACHMENT E-
BMP Calculations
Volume Input Criteria - Infiltration Basin J ................................................................................................. E-1
Volume Input Criteria - Infiltration Basin B ............................................................................................... E-2
Water Quality and Recharge Summary ...................................................................................................... E-3
Pages E-1 - E-3
604597: I-91 Interchange 19
Northampton, MA
NOI Submission
BMP Calculations
Volume Input Criteria
Infiltration Basin J
2/27/2018
By: MJR
Checked by: DPL
Infiltration Basin J
Forebay:
Elevation
(FT)
Delta
Elev.
(FT)
Area
(SF)
Volume
(CF)
Void
Ratio
Volume
w/Ratio
(CF)
Cumulative
Volume (CF)
Water
Quality
Volume
(CF)
128.00 183 0 100%0 0
1.00 270
129.00 356 270 100%270 270 270
1.00 471
130.00 586 471 100%471 740.5
Infiltration Basin J:
Elevation
(FT)
Delta
Elev.
(FT)
Area
(SF)
High
Marsh
Area
(SF)
Net
Area
(SF)
Volume
(CF)Void Ratio
Volume
w/Ratio
(CF)
Cumulative
Volume
(CF)
Water
Quality
Volume
(CF)
123.00 1035 0 1035 0 100%0 0
1.00 1254
124.00 1472 0 1472 1254 100%1254 1254
1.00 1721
125.00 1970 0 1970 1721 100%1721 2975
0.75 2177
125.75 2383 0 2383 1632 100%1632 4607 4607
0.25 2453
126.00 2522 0 2522 613 100%613 5220
1.00 2643
127.00 3130 0 2763 2643 100%2643 7863
E - 1
604597: I-91 Interchange 19
Northampton, MA
NOI Submittal
BMP Calculations
Volume Input Criteria
Infiltration Basin B
2/27/2018
By: MJR
Checked by: DPL
Infiltration Basin B
Forebay:
Elevation
(FT)
Delta
Elev.
(FT)
Area
(SF)
Volume
(CF)
Void
Ratio
Volume
w/Ratio
(CF)
Cumulative
Volume (CF)
Water
Quality
Volume
(CF)
130.00 196 0 100%0 0
1.00 307
131.00 418 307 100%307 307
1.00 568
132.00 717 568 100%568 875 875
1.00 885
133.00 1053 885 100%885 1760
1.00 1221
134.00 1388 1221 100%1221 2980
1.00 1576
135.00 1764 1576 100%1576 4556
1.00 1972
136.00 2180 1972 100%1972 6528
Infiltration Basin:
Elevation
(FT)
Delta
Elev.
(FT)
Area
(SF)
Volume
(CF)
Void
Ratio
Volume
w/Ratio
(CF)
Cumulative
Volume (CF)
Water
Quality
Volume
(CF)
130.00 1495 0 100%0 0
1.00 1894
131.00 2292 1894 100%1894 1894
1.00 2729
132.00 3166 2729 100%2729 4623
0.75 3498
132.75 3829 2623 100%2623 7246 7246
0.25 3937
133.00 4045 984 100%984 8230
1.00 4482
134.00 4918 4482 100%4482 12711
1.00 5371
135.00 5823 5371 100%5371 18082
1.00 6292
136.00 6761 6292 100%6292 24374
E - 2
604597: I-91 Interchange 19
Northampton, MA
NOI Submittal
BMP Calculations
Water Quality and Recharge Summary
2/27/2018
By: MJR
Checked by: DPL
Infiltration Basin J
Forebay
Total Contributing Impervious Area:16,720 SF
Forebay Volume Required: (0.1 inch x Area)140 CF
Forebay Volume Provided:270 CF
Infiltration Basin:
Total Contributing Impervious Area:16,720 SF
Required Water Qualtiy Volume: (1 inch x Area)1,394 CF
Required Recharge Volume (0.35 inches x Impervious Area)488 CF
Provided Water Quality / Recharge Volume:4,607 CF
Required 72 Hour Drawdown:
Rv:4,607 CF
K (Saturated Hydraulic Conductivity, Rawls Table for Loamy Sand):2.41 IN/HR
Bottom Area of Basin (elevation 123):1,035 SF
Drawdown Time:22 HR
Infiltration Basin B
Forebay
Total Contributing Impervious Area:73,887 SF
Forebay Volume Required: (0.1 inch x Area)616 CF
Forebay Volume Provided:875 CF
Infiltration Basin:
Total Contributing Impervious Area:73,887 SF
Required Water Qualtiy Volume: (1/2 inch x Impervious Area)3,079 CF
Required Recharge Volume (0.35 inches x Impervious Area)2,155 CF
Provided Water Quality / Recharge Volume:7,246 CF
Required 72 Hour Drawdown:
Rv:7,246 CF
K (Saturated Hydraulic Conductivity, Rawls Table for Sandy Loam):1.02 IN/HR
Bottom Area of Basin (elevation 130):1,495 SF
Drawdown Time:57 HR
Recharge Volume for Entire Site:
Total Existing Impervious Area:399,183 SF
Total Proposed Impervious Area:440,815 SF
Net Total Additional Impervious Area:41,632 SF
Required Recharge Volume (0.35 inches x Additional Impervious Area)1,214 CF
Provided Water Quality / Recharge Volume:11,853 CF
E - 3
Stormwater Report
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
ATTACHMENT F-
Peak Rate Attenuation Modeling Output
Existing Model Output ........................................................................................................................ F-1 - F-45
Proposed Model Output ................................................................................................................... F-46 - F-99
(The model outputs included in this report are the summaries only. Hydrograph Tables and
associated graphs for existing and proposed are 596 and 1,686 pages, respectively. These full
outputs are available if requested.)
Pages F-1 - F-99
604597 - Existing Drainage Model
Project Summary
604597
NorthamptonTitle
Michael Rieger, PEEngineer
TranSystemsCompany
10/25/2017Date
Notes
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F - 2
40Runoff CN-Area, 2 years
EX-K
39Runoff CN-Area, 2 years
EX-H
38Runoff CN-Area, 2 years
EX-G
37Runoff CN-Area, 2 years
EX-F
36Runoff CN-Area, 2 years
EX-E
35Runoff CN-Area, 2 years
EX-D
34Runoff CN-Area, 2 years
EX-C
33Runoff CN-Area, 2 years
EX-B
32Runoff CN-Area, 2 years
EX-A
30Time of Concentration Calculations, 2 years
EX-K
28Time of Concentration Calculations, 2 years
EX-H
26Time of Concentration Calculations, 2 years
EX-G
24Time of Concentration Calculations, 2 years
EX-F
22Time of Concentration Calculations, 2 years
EX-E
20Time of Concentration Calculations, 2 years
EX-D
18Time of Concentration Calculations, 2 years
EX-C
16Time of Concentration Calculations, 2 years
EX-B
14Time of Concentration Calculations, 2 years
EX-A
11Time-Depth Curve, 2 years
8Time-Depth Curve, 10 years
5Time-Depth Curve, 100 years
Type III 24-hr Northampton
2Master Network Summary
Table of Contents
F
-
3
Table of Contents
40Runoff CN-Area, 2 years
EX-K
39Runoff CN-Area, 2 years
EX-H
38Runoff CN-Area, 2 years
EX-G
37Runoff CN-Area, 2 years
EX-F
36Runoff CN-Area, 2 years
EX-E
35Runoff CN-Area, 2 years
EX-D
34Runoff CN-Area, 2 years
EX-C
33Runoff CN-Area, 2 years
EX-B
32Runoff CN-Area, 2 years
EX-A
30Time of Concentration Calculations, 2 years
EX-K
28Time of Concentration Calculations, 2 years
EX-H
26Time of Concentration Calculations, 2 years
EX-G
24Time of Concentration Calculations, 2 years
EX-F
22Time of Concentration Calculations, 2 years
EX-E
20Time of Concentration Calculations, 2 years
EX-D
18Time of Concentration Calculations, 2 years
EX-C 16Time of Concentration Calculations, 2 yearsEX-B 14Time of Concentration Calculations, 2 yearsEX-A 11Time-Depth Curve, 2 years 8Time-Depth Curve, 10 years 5Time-Depth Curve, 100 yearsType III 24-hr Northampton 2Master Network Summary
F
-
4
604597 - Existing Drainage Model
Subsection: Master Network Summary
Catchments Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph Volume
(ft³)
Return
Event
(years)
ScenarioLabel
6.66726.5023,33922-YearEX-A
11.59726.0041,5921010-YearEX-A
17.85726.0065,781100100-YearEX-A
0.43727.502,06122-YearEX-B
1.61727.005,9021010-YearEX-B
3.51726.5012,264100100-YearEX-B
3.68726.5012,77022-YearEX-C
6.71726.0023,7231010-YearEX-C
10.65726.0038,511100100-YearEX-C
0.44726.001,75422-YearEX-D
0.66726.002,7021010-YearEX-D
0.94726.003,905100100-YearEX-D
0.77728.004,40422-YearEX-F
3.58727.0013,4781010-YearEX-F
8.23726.5028,924100100-YearEX-F
1.79726.007,02322-YearEX-E
2.73726.0010,9621010-YearEX-E
3.91726.0015,966100100-YearEX-E
1.81726.006,72722-YearEX-H
2.85726.0010,9221010-YearEX-H
4.15726.0016,297100100-YearEX-H
7.68726.5026,62422-YearEX-G
14.26726.5050,1711010-YearEX-G
22.84726.0082,177100100-YearEX-G
0.19740.001,85622-YearEX-K
1.68727.507,0791010-YearEX-K
4.63727.0016,720100100-YearEX-K
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F
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604597 - Existing Drainage Model
Subsection: Master Network Summary
Node Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph Volume
(ft³)
Return
Event
(years)
ScenarioLabel
0.77728.004,40422-YearDP-F
3.58727.0013,4781010-YearDP-F
8.23726.5028,924100100-YearDP-F
1.81726.006,72722-YearDP-H
2.85726.0010,9221010-YearDP-H
4.15726.0016,297100100-YearDP-H
0.44726.001,75422-YearDP-D
0.66726.002,7021010-YearDP-D
0.94726.003,905100100-YearDP-D
3.68726.5012,77022-YearDP-C
6.71726.0023,7231010-YearDP-C
10.65726.0038,511100100-YearDP-C
11.30727.0039,36922-YearDP-CG1
20.87726.5073,8581010-YearDP-CG1
26.62726.50121,221100100-YearDP-CG1
7.68726.5026,62422-YearDP-G
14.26726.5050,1711010-YearDP-G
22.84726.0082,177100100-YearDP-G
11.26727.5039,34722-YearDP-CG2
20.83727.0073,8261010-YearDP-CG2
26.60726.50121,178100100-YearDP-CG2
0.43727.502,06122-YearDP-B
1.61727.005,9021010-YearDP-B
3.51726.5012,264100100-YearDP-B
1.79726.007,02322-YearDP-E
2.73726.0010,9621010-YearDP-E
3.91726.0015,966100100-YearDP-E
13.78727.5050,15422-YearDP-BCDEG
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604597 - Existing Drainage Model
Subsection: Master Network Summary
Node Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph Volume
(ft³)
Return
Event
(years)
ScenarioLabel
25.66727.5093,3471010-YearDP-BCDEG
34.54726.50154,049100100-YearDP-BCDEG
13.71728.0050,11822-Year12+85 MH
25.57728.0093,2961010-Year12+85 MH
31.33721.50154,971100100-Year12+85 MH
6.66726.5023,33922-YearDP-A
11.59726.0041,5921010-YearDP-A
17.85726.0065,781100100-YearDP-A
13.67728.5050,08722-Year30" Outfall
25.51728.0093,2511010-Year30" Outfall
31.33738.00154,911100100-Year30" Outfall
20.01727.5073,42622-YearDP-River
36.70727.00134,8431010-YearDP-River
49.18726.00220,692100100-YearDP-River
0.19740.001,85622-YearDP-K
1.68727.507,0791010-YearDP-K
4.63727.0016,720100100-YearDP-K
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604597 - Existing Drainage Model
Storm Event: 100-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 100 yearsSubsection: Time-Depth Curve
Time-Depth Curve: 100-year, 24-hr rainfall
100-year, 24-hr
rainfallLabel
min0.00Start Time
min6.00Increment
min1,440.00End Time
years100Return Event
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth(in)Depth(in)Depth(in)Depth(in)Depth(in)Time(min)
0.00.00.00.00.00.00
0.10.10.00.00.030.00
0.10.10.10.10.160.00
0.10.10.10.10.190.00
0.20.10.10.10.1120.00
0.20.20.20.20.2150.00
0.20.20.20.20.2180.00
0.30.30.30.20.2210.00
0.30.30.30.30.3240.00
0.40.30.30.30.3270.00
0.40.40.40.40.4300.00
0.50.40.40.40.4330.00
0.50.50.50.50.5360.00
0.60.60.50.50.5390.00
0.60.60.60.60.6420.00
0.70.70.70.70.7450.00
0.80.80.80.70.7480.00
0.90.90.90.80.8510.00
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F
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604597 - Existing Drainage Model
Storm Event: 100-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 100 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
1.01.01.01.00.9540.00
1.21.11.11.11.1570.00
1.31.31.31.21.2600.00
1.61.51.51.41.4630.00
1.81.81.71.61.6660.00
2.72.42.22.01.9690.00
4.44.24.03.73.2720.00
4.84.74.64.64.5750.00
5.04.94.94.84.8780.00
5.25.15.15.15.0810.00
5.35.35.35.25.2840.00
5.45.45.45.45.3870.00
5.65.55.55.55.5900.00
5.75.65.65.65.6930.00
5.75.75.75.75.7960.00
5.85.85.85.85.7990.00
5.95.95.85.85.81,020.00
5.95.95.95.95.91,050.00
6.06.06.05.95.91,080.00
6.06.06.06.06.01,110.00
6.16.16.16.06.01,140.00
6.16.16.16.16.11,170.00
6.26.16.16.16.11,200.00
6.26.26.26.26.21,230.00
6.26.26.26.26.21,260.00
6.36.36.36.26.21,290.00
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F
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604597 - Existing Drainage Model
Storm Event: 100-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 100 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
6.36.36.36.36.31,320.00
6.36.36.36.36.31,350.00
6.46.46.46.36.31,380.00
6.46.46.46.46.41,410.00
(N/A)(N/A)(N/A)(N/A)6.41,440.00
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604597 - Existing Drainage Model
Storm Event: 10-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 10 yearsSubsection: Time-Depth Curve
Time-Depth Curve: 10-year, 24-hr rainfall
10-year, 24-hr
rainfallLabel
min0.00Start Time
min6.00Increment
min1,440.00End Time
years10Return Event
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth(in)Depth(in)Depth(in)Depth(in)Depth(in)Time(min)
0.00.00.00.00.00.00
0.00.00.00.00.030.00
0.10.10.10.00.060.00
0.10.10.10.10.190.00
0.10.10.10.10.1120.00
0.10.10.10.10.1150.00
0.20.20.10.10.1180.00
0.20.20.20.20.2210.00
0.20.20.20.20.2240.00
0.20.20.20.20.2270.00
0.30.30.30.30.3300.00
0.30.30.30.30.3330.00
0.40.30.30.30.3360.00
0.40.40.40.40.4390.00
0.40.40.40.40.4420.00
0.50.50.50.50.5450.00
0.60.60.50.50.5480.00
0.60.60.60.60.6510.00
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1
604597 - Existing Drainage Model
Storm Event: 10-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 10 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.70.70.70.70.7540.00
0.80.80.80.80.7570.00
0.90.90.90.90.9600.00
1.11.11.01.01.0630.00
1.31.21.21.21.1660.00
1.91.71.51.41.3690.00
3.13.02.82.62.2720.00
3.33.33.33.23.2750.00
3.53.53.43.43.4780.00
3.63.63.63.63.5810.00
3.73.73.73.73.6840.00
3.83.83.83.83.8870.00
3.93.93.93.93.8900.00
4.04.03.93.93.9930.00
4.04.04.04.04.0960.00
4.14.14.14.14.0990.00
4.14.14.14.14.11,020.00
4.24.24.24.14.11,050.00
4.24.24.24.24.21,080.00
4.24.24.24.24.21,110.00
4.34.34.34.34.21,140.00
4.34.34.34.34.31,170.00
4.34.34.34.34.31,200.00
4.44.44.34.34.31,230.00
4.44.44.44.44.41,260.00
4.44.44.44.44.41,290.00
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F
-
1
2
604597 - Existing Drainage Model
Storm Event: 10-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 10 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
4.44.44.44.44.41,320.00
4.54.54.44.44.41,350.00
4.54.54.54.54.51,380.00
4.54.54.54.54.51,410.00
(N/A)(N/A)(N/A)(N/A)4.51,440.00
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F
-
1
3
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 2 yearsSubsection: Time-Depth Curve
Time-Depth Curve: 2-year, 24-hr rainfall
2-year, 24-hr
rainfallLabel
min0.00Start Time
min6.00Increment
min1,440.00End Time
years2Return Event
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth(in)Depth(in)Depth(in)Depth(in)Depth(in)Time(min)
0.00.00.00.00.00.00
0.00.00.00.00.030.00
0.00.00.00.00.060.00
0.10.10.10.00.090.00
0.10.10.10.10.1120.00
0.10.10.10.10.1150.00
0.10.10.10.10.1180.00
0.10.10.10.10.1210.00
0.10.10.10.10.1240.00
0.20.20.20.20.1270.00
0.20.20.20.20.2300.00
0.20.20.20.20.2330.00
0.20.20.20.20.2360.00
0.30.30.30.20.2390.00
0.30.30.30.30.3420.00
0.30.30.30.30.3450.00
0.40.40.40.30.3480.00
0.40.40.40.40.4510.00
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F
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1
4
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 2 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.50.50.50.40.4540.00
0.60.50.50.50.5570.00
0.60.60.60.60.6600.00
0.70.70.70.70.6630.00
0.90.80.80.80.7660.00
1.21.11.00.90.9690.00
2.12.01.91.81.5720.00
2.22.22.22.12.1750.00
2.32.32.32.32.2780.00
2.42.42.42.42.4810.00
2.52.52.52.42.4840.00
2.62.52.52.52.5870.00
2.62.62.62.62.6900.00
2.72.62.62.62.6930.00
2.72.72.72.72.7960.00
2.72.72.72.72.7990.00
2.82.72.72.72.71,020.00
2.82.82.82.82.81,050.00
2.82.82.82.82.81,080.00
2.82.82.82.82.81,110.00
2.82.82.82.82.81,140.00
2.92.92.92.92.91,170.00
2.92.92.92.92.91,200.00
2.92.92.92.92.91,230.00
2.92.92.92.92.91,260.00
2.92.92.92.92.91,290.00
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F
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1
5
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 2 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
3.03.02.92.92.91,320.00
3.03.03.03.03.01,350.00
3.03.03.03.03.01,380.00
3.03.03.03.03.01,410.00
(N/A)(N/A)(N/A)(N/A)3.01,440.00
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F
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1
6
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-A
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
Page 14 of 4227 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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1
7
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-A
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
-
1
8
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-B
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
1
9
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-B
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
-
2
0
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-C
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
2
1
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-C
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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2
2
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-D
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
2
3
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-D
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
-
2
4
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-E
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
2
5
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-E
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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2
6
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-F
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
2
7
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-F
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
-
2
8
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-G
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
2
9
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-G
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
-
3
0
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-H
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
3
1
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-H
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
-
3
2
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-K
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
3
3
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-K
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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3
4
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-A
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.0113,76898.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.033,90261.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
55.0000.00.013,51255.000Woods - good - Soil B
86.613(N/A)(N/A)161,182(N/A)COMPOSITE AREA & WEIGHTED CN --->
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F
-
3
5
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-B
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.03,94098.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.048,91061.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
55.0000.00.09,35455.000Woods - good - Soil B
62.441(N/A)(N/A)62,204(N/A)COMPOSITE AREA & WEIGHTED CN --->
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F
-
3
6
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-C
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.063,95198.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.037,20161.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
84.392(N/A)(N/A)101,152(N/A)COMPOSITE AREA & WEIGHTED CN --->
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F
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3
7
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-D
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.07,60998.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
98.000(N/A)(N/A)7,609(N/A)COMPOSITE AREA & WEIGHTED CN --->
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F
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3
8
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-E
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.030,81398.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.091061.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
96.939(N/A)(N/A)31,723(N/A)COMPOSITE AREA & WEIGHTED CN --->
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F
-
3
9
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-F
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.014,44898.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.034,48361.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
55.0000.00.0109,88755.000Woods - good - Soil B
60.215(N/A)(N/A)158,818(N/A)COMPOSITE AREA & WEIGHTED CN --->
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F
-
4
0
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-G
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.0133,67898.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.087,39561.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
83.373(N/A)(N/A)221,073(N/A)COMPOSITE AREA & WEIGHTED CN --->
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1
604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-H
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.030,97698.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.03,39861.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
94.342(N/A)(N/A)34,374(N/A)COMPOSITE AREA & WEIGHTED CN --->
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604597 - Existing Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: EX-K
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
61.0000.00.06,36561.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
55.0000.00.0108,23655.000Woods - good - Soil B
55.333(N/A)(N/A)114,601(N/A)COMPOSITE AREA & WEIGHTED CN --->
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Type III 24-hr Northampton (Time-Depth Curve, 2years)...11, 12, 13
Type III 24-hr Northampton (Time-Depth Curve, 100
years)...5, 6, 7
Type III 24-hr Northampton (Time-Depth Curve, 10
years)...8, 9, 10
T
Master Network Summary...2, 3, 4
M
EX-K (Time of Concentration Calculations, 2 years)...30,
31
EX-K (Runoff CN-Area, 2 years)...40
EX-H (Time of Concentration Calculations, 2 years)...28,
29
EX-H (Runoff CN-Area, 2 years)...39
EX-G (Time of Concentration Calculations, 2 years)...26,
27
EX-G (Runoff CN-Area, 2 years)...38
EX-F (Time of Concentration Calculations, 2 years)...24, 25
EX-F (Runoff CN-Area, 2 years)...37
EX-E (Time of Concentration Calculations, 2 years)...22,
23
EX-E (Runoff CN-Area, 2 years)...36
EX-D (Time of Concentration Calculations, 2 years)...20,21
EX-D (Runoff CN-Area, 2 years)...35
EX-C (Time of Concentration Calculations, 2 years)...18,
19
EX-C (Runoff CN-Area, 2 years)...34
EX-B (Time of Concentration Calculations, 2 years)...16,
17
EX-B (Runoff CN-Area, 2 years)...33
EX-A (Time of Concentration Calculations, 2 years)...14,15
EX-A (Runoff CN-Area, 2 years)...32
E
604597 - Existing Drainage Model
Index
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604597 - Existing Drainage Model
Type III 24-hr Northampton (Time-Depth Curve, 2
years)...11, 12, 13
Type III 24-hr Northampton (Time-Depth Curve, 100
years)...5, 6, 7
Type III 24-hr Northampton (Time-Depth Curve, 10
years)...8, 9, 10
T
Master Network Summary...2, 3, 4
M
EX-K (Time of Concentration Calculations, 2 years)...30,31
EX-K (Runoff CN-Area, 2 years)...40
EX-H (Time of Concentration Calculations, 2 years)...28,
29
EX-H (Runoff CN-Area, 2 years)...39
EX-G (Time of Concentration Calculations, 2 years)...26,
27
EX-G (Runoff CN-Area, 2 years)...38
EX-F (Time of Concentration Calculations, 2 years)...24, 25
EX-F (Runoff CN-Area, 2 years)...37
EX-E (Time of Concentration Calculations, 2 years)...22,
23
EX-E (Runoff CN-Area, 2 years)...36
EX-D (Time of Concentration Calculations, 2 years)...20,
21
EX-D (Runoff CN-Area, 2 years)...35
EX-C (Time of Concentration Calculations, 2 years)...18,19
EX-C (Runoff CN-Area, 2 years)...34EX-B (Time of Concentration Calculations, 2 years)...16,17EX-B (Runoff CN-Area, 2 years)...33EX-A (Time of Concentration Calculations, 2 years)...14,15EX-A (Runoff CN-Area, 2 years)...32E
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604597 - Proposed Drainage Model
Project Summary
604597
NorthamptonTitle
Michael Rieger, PEEngineer
TranSystemsCompany
10/25/2017Date
Notes
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F - 47
48Runoff CN-Area, 2 years
PR-Pond J
47Runoff CN-Area, 2 years
PR-Pond B
46Runoff CN-Area, 2 years
PR-K
45Runoff CN-Area, 2 years
PR-J
44Runoff CN-Area, 2 years
PR-H
43Runoff CN-Area, 2 years
PR-G
42Runoff CN-Area, 2 years
PR-F
41Runoff CN-Area, 2 years
PR-D
40Runoff CN-Area, 2 years
PR-C
39Runoff CN-Area, 2 years
PR-B
38Runoff CN-Area, 2 years
PR-A
36Time of Concentration Calculations, 2 years
PR-Pond J
34Time of Concentration Calculations, 2 years
PR-Pond B
32Time of Concentration Calculations, 2 years
PR-K
30Time of Concentration Calculations, 2 years
PR-J
28Time of Concentration Calculations, 2 years
PR-H
26Time of Concentration Calculations, 2 years
PR-G
24Time of Concentration Calculations, 2 years
PR-F
22Time of Concentration Calculations, 2 years
PR-D
20Time of Concentration Calculations, 2 years
PR-C
18Time of Concentration Calculations, 2 years
PR-B
16Time of Concentration Calculations, 2 years
PR-A
13Time-Depth Curve, 2 years
10Time-Depth Curve, 10 years
7Time-Depth Curve, 100 years
Type III 24-hr Northampton
2Master Network Summary
Table of Contents
F
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48Runoff CN-Area, 2 years
PR-Pond J
47Runoff CN-Area, 2 years
PR-Pond B
46Runoff CN-Area, 2 years
PR-K
45Runoff CN-Area, 2 years
PR-J
44Runoff CN-Area, 2 years
PR-H
43Runoff CN-Area, 2 years
PR-G
42Runoff CN-Area, 2 years
PR-F
41Runoff CN-Area, 2 years
PR-D
40Runoff CN-Area, 2 years
PR-C
39Runoff CN-Area, 2 years
PR-B
38Runoff CN-Area, 2 years
PR-A
36Time of Concentration Calculations, 2 years
PR-Pond J
34Time of Concentration Calculations, 2 years
PR-Pond B
32Time of Concentration Calculations, 2 years
PR-K
30Time of Concentration Calculations, 2 years
PR-J
28Time of Concentration Calculations, 2 years
PR-H
26Time of Concentration Calculations, 2 years
PR-G
24Time of Concentration Calculations, 2 years
PR-F
22Time of Concentration Calculations, 2 years
PR-D
20Time of Concentration Calculations, 2 years
PR-C 18Time of Concentration Calculations, 2 yearsPR-B 16Time of Concentration Calculations, 2 yearsPR-A 13Time-Depth Curve, 2 years 10Time-Depth Curve, 10 years 7Time-Depth Curve, 100 yearsType III 24-hr Northampton 2Master Network Summary
Table of Contents
F
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Table of Contents
48Runoff CN-Area, 2 years
PR-Pond J
47Runoff CN-Area, 2 years
PR-Pond B
46Runoff CN-Area, 2 years
PR-K
45Runoff CN-Area, 2 years
PR-J
44Runoff CN-Area, 2 years
PR-H
43Runoff CN-Area, 2 years
PR-G
42Runoff CN-Area, 2 years
PR-F
41Runoff CN-Area, 2 years
PR-D 40Runoff CN-Area, 2 yearsPR-C 39Runoff CN-Area, 2 yearsPR-B 38Runoff CN-Area, 2 yearsPR-A 36Time of Concentration Calculations, 2 yearsPR-Pond J 34Time of Concentration Calculations, 2 yearsPR-Pond B 32Time of Concentration Calculations, 2 yearsPR-K 30Time of Concentration Calculations, 2 yearsPR-J 28Time of Concentration Calculations, 2 yearsPR-H 26Time of Concentration Calculations, 2 yearsPR-G 24Time of Concentration Calculations, 2 yearsPR-F 22Time of Concentration Calculations, 2 yearsPR-D 20Time of Concentration Calculations, 2 yearsPR-C 18Time of Concentration Calculations, 2 yearsPR-B 16Time of Concentration Calculations, 2 yearsPR-A 13Time-Depth Curve, 2 years 10Time-Depth Curve, 10 years 7Time-Depth Curve, 100 yearsType III 24-hr Northampton 2Master Network Summary
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604597 - Proposed Drainage Model
Subsection: Master Network Summary
Catchments Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph Volume
(ft³)
Return
Event
(years)
ScenarioLabel
5.01726.5017,46322-YearPR-A
8.84726.0031,5501010-YearPR-A
13.75726.0050,329100100-YearPR-A
4.42726.5015,46122-YearPR-B
7.68726.0027,5531010-YearPR-B
11.83726.0043,576100100-YearPR-B
3.70726.5012,82922-YearPR-C
7.00726.5024,5271010-YearPR-C
11.32726.0040,539100100-YearPR-C
0.34726.001,37322-YearPR-D
0.52726.002,1151010-YearPR-D
0.74726.003,056100100-YearPR-D
0.67727.503,22022-YearPR-F
2.52727.009,2221010-YearPR-F
5.49726.5019,163100100-YearPR-F
1.47726.005,34422-YearPR-H
2.38726.008,9081010-YearPR-H
3.51726.0013,511100100-YearPR-H
9.03726.5031,32822-YearPR-G
16.47726.0058,2001010-YearPR-G
26.12726.0094,483100100-YearPR-G
1.01726.003,61222-YearPR-J
1.65726.006,1011010-YearPR-J
2.45726.009,330100100-YearPR-J
0.13728.0065422-YearPR-Pond J
0.52727.001,9351010-YearPR-Pond J
1.17726.504,085100100-YearPR-Pond J
0.21728.001,07722-YearPR-Pond B
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604597 - Proposed Drainage Model
Subsection: Master Network Summary
Catchments Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph Volume
(ft³)
Return
Event
(years)
ScenarioLabel
0.86727.003,1861010-YearPR-Pond B
1.92726.506,725100100-YearPR-Pond B
0.18739.501,57822-YearPR-K
1.39727.505,7131010-YearPR-K
3.68727.0013,208100100-YearPR-K
Node Summary
Peak Flow(ft³/s)Time to Peak(min)Hydrograph Volume(ft³)ReturnEvent(years)
ScenarioLabel
0.67727.503,22022-YearDP-F
2.52727.009,2221010-YearDP-F
5.49726.5022,764100100-YearDP-F
1.47726.005,34422-YearDP-H
2.38726.008,9081010-YearDP-H
3.51726.0013,511100100-YearDP-H
0.34726.001,37322-YearDP-D
0.52726.002,1151010-YearDP-D
0.74726.003,056100100-YearDP-D
3.70726.5012,82922-YearDP-C
7.00726.5024,5271010-YearDP-C
11.32726.0040,539100100-YearDP-C
12.66727.0044,12822-YearDP-CG1
23.38726.5082,6851010-YearDP-CG1
43.37723.00135,294100100-YearDP-CG1
9.03726.5031,32822-YearDP-G
16.47726.0058,2001010-YearDP-G
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604597 - Proposed Drainage Model
Subsection: Master Network Summary
Node Summary
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph Volume
(ft³)
Return
Event
(years)
ScenarioLabel
26.12726.0094,483100100-YearDP-G
12.61727.5044,10222-YearDP-CG2
23.33727.0082,6481010-YearDP-CG2
29.63720.00136,216100100-YearDP-CG2
0.23852.003,40822-YearDP-B
2.42747.0016,7341010-YearDP-B
4.67743.0035,460100100-YearDP-B
12.89728.0048,85522-YearDP-BCDEG
24.43728.00101,4541010-YearDP-BCDEG
34.34740.00175,563100100-YearDP-BCDEG
12.83728.5048,82122-Year12+85 MH
24.32728.50101,4021010-Year12+85 MH
31.33721.50176,477100100-Year12+85 MH
5.01726.5017,46322-YearDP-A
8.84726.0031,5501010-YearDP-A
13.75726.0050,329100100-YearDP-A
12.79729.0048,79122-Year30" Outfall
24.24729.00101,3561010-Year30" Outfall
31.33738.50176,414100100-Year30" Outfall
17.48727.5066,25422-YearDP-River
32.44727.50132,9061010-YearDP-River
45.08726.00226,743100100-YearDP-River
0.18739.501,57822-YearDP-K
1.39727.505,7131010-YearDP-K
3.68727.0013,208100100-YearDP-K
Pond Summary
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604597 - Proposed Drainage Model
Subsection: Master Network Summary
Pond Summary
Maximum Pond
Storage
(ft³)
Maximum Water
Surface Elevation
(ft)
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
(N/A)(N/A)3.98727.0015,15722-YearInfiltration BasinB (IN)
8,258133.010.23852.003,40822-YearInfiltration BasinB (OUT)
(N/A)(N/A)6.86726.5029,2831010-YearInfiltration Basin
B (IN)
11,368133.712.42747.0016,7341010-YearInfiltration Basin
B (OUT)
(N/A)(N/A)11.53726.5048,788100100-YearInfiltration BasinB (IN)
16,703134.754.67743.0035,460100100-YearInfiltration Basin
B (OUT)
(N/A)(N/A)4.42726.5015,46122-YearForebay B (IN)
1,759133.023.78727.0014,08022-YearForebay B (OUT)
(N/A)(N/A)7.68726.0027,5531010-YearForebay B (IN)
2,608133.716.01726.5026,0971010-YearForebay B (OUT)
(N/A)(N/A)11.83726.0043,576100100-YearForebay B (IN)
4,146134.769.61726.5042,062100100-YearForebay B (OUT)
(N/A)(N/A)1.01726.003,61222-YearForebay J (IN)
29128.111.00726.503,61222-YearForebay J (OUT)
(N/A)(N/A)1.65726.006,1011010-YearForebay J (IN)
48128.181.64726.506,1001010-YearForebay J (OUT)
(N/A)(N/A)2.45726.009,330100100-YearForebay J (IN)
71128.272.44726.509,329100100-YearForebay J (OUT)
(N/A)(N/A)1.12727.004,26622-YearInfiltration Basin
J (IN)
1,911124.390.000.00022-YearInfiltration BasinJ (OUT)
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604597 - Proposed Drainage Model
Subsection: Master Network Summary
Pond Summary
Maximum Pond
Storage
(ft³)
Maximum Water
Surface Elevation
(ft)
Peak Flow
(ft³/s)
Time to Peak
(min)
Hydrograph
Volume
(ft³)
Return
Event
(years)
ScenarioLabel
(N/A)(N/A)2.16726.508,0361010-YearInfiltration Basin
J (IN)
4,198125.580.000.0001010-YearInfiltration BasinJ (OUT)
(N/A)(N/A)3.61726.5013,414100100-YearInfiltration Basin
J (IN)
4,952125.891.66736.003,602100100-YearInfiltration Basin
J (OUT)
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604597 - Proposed Drainage Model
Storm Event: 100-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 100 yearsSubsection: Time-Depth Curve
Time-Depth Curve: 100-year, 24-hr rainfall
100-year, 24-hr
rainfallLabel
min0.00Start Time
min6.00Increment
min1,440.00End Time
years100Return Event
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth(in)Depth(in)Depth(in)Depth(in)Depth(in)Time(min)
0.00.00.00.00.00.00
0.10.10.00.00.030.00
0.10.10.10.10.160.00
0.10.10.10.10.190.00
0.20.10.10.10.1120.00
0.20.20.20.20.2150.00
0.20.20.20.20.2180.00
0.30.30.30.20.2210.00
0.30.30.30.30.3240.00
0.40.30.30.30.3270.00
0.40.40.40.40.4300.00
0.50.40.40.40.4330.00
0.50.50.50.50.5360.00
0.60.60.50.50.5390.00
0.60.60.60.60.6420.00
0.70.70.70.70.7450.00
0.80.80.80.70.7480.00
0.90.90.90.80.8510.00
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604597 - Proposed Drainage Model
Storm Event: 100-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 100 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
1.01.01.01.00.9540.00
1.21.11.11.11.1570.00
1.31.31.31.21.2600.00
1.61.51.51.41.4630.00
1.81.81.71.61.6660.00
2.72.42.22.01.9690.00
4.44.24.03.73.2720.00
4.84.74.64.64.5750.00
5.04.94.94.84.8780.00
5.25.15.15.15.0810.00
5.35.35.35.25.2840.00
5.45.45.45.45.3870.00
5.65.55.55.55.5900.00
5.75.65.65.65.6930.00
5.75.75.75.75.7960.00
5.85.85.85.85.7990.00
5.95.95.85.85.81,020.00
5.95.95.95.95.91,050.00
6.06.06.05.95.91,080.00
6.06.06.06.06.01,110.00
6.16.16.16.06.01,140.00
6.16.16.16.16.11,170.00
6.26.16.16.16.11,200.00
6.26.26.26.26.21,230.00
6.26.26.26.26.21,260.00
6.36.36.36.26.21,290.00
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604597 - Proposed Drainage Model
Storm Event: 100-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 100 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
6.36.36.36.36.31,320.00
6.36.36.36.36.31,350.00
6.46.46.46.36.31,380.00
6.46.46.46.46.41,410.00
(N/A)(N/A)(N/A)(N/A)6.41,440.00
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604597 - Proposed Drainage Model
Storm Event: 10-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 10 yearsSubsection: Time-Depth Curve
Time-Depth Curve: 10-year, 24-hr rainfall
10-year, 24-hr
rainfallLabel
min0.00Start Time
min6.00Increment
min1,440.00End Time
years10Return Event
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth(in)Depth(in)Depth(in)Depth(in)Depth(in)Time(min)
0.00.00.00.00.00.00
0.00.00.00.00.030.00
0.10.10.10.00.060.00
0.10.10.10.10.190.00
0.10.10.10.10.1120.00
0.10.10.10.10.1150.00
0.20.20.10.10.1180.00
0.20.20.20.20.2210.00
0.20.20.20.20.2240.00
0.20.20.20.20.2270.00
0.30.30.30.30.3300.00
0.30.30.30.30.3330.00
0.40.30.30.30.3360.00
0.40.40.40.40.4390.00
0.40.40.40.40.4420.00
0.50.50.50.50.5450.00
0.60.60.50.50.5480.00
0.60.60.60.60.6510.00
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9
604597 - Proposed Drainage Model
Storm Event: 10-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 10 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.70.70.70.70.7540.00
0.80.80.80.80.7570.00
0.90.90.90.90.9600.00
1.11.11.01.01.0630.00
1.31.21.21.21.1660.00
1.91.71.51.41.3690.00
3.13.02.82.62.2720.00
3.33.33.33.23.2750.00
3.53.53.43.43.4780.00
3.63.63.63.63.5810.00
3.73.73.73.73.6840.00
3.83.83.83.83.8870.00
3.93.93.93.93.8900.00
4.04.03.93.93.9930.00
4.04.04.04.04.0960.00
4.14.14.14.14.0990.00
4.14.14.14.14.11,020.00
4.24.24.24.14.11,050.00
4.24.24.24.24.21,080.00
4.24.24.24.24.21,110.00
4.34.34.34.34.21,140.00
4.34.34.34.34.31,170.00
4.34.34.34.34.31,200.00
4.44.44.34.34.31,230.00
4.44.44.44.44.41,260.00
4.44.44.44.44.41,290.00
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F
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6
0
604597 - Proposed Drainage Model
Storm Event: 10-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 10 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
4.44.44.44.44.41,320.00
4.54.54.44.44.41,350.00
4.54.54.54.54.51,380.00
4.54.54.54.54.51,410.00
(N/A)(N/A)(N/A)(N/A)4.51,440.00
Page 12 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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6
1
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 2 yearsSubsection: Time-Depth Curve
Time-Depth Curve: 2-year, 24-hr rainfall
2-year, 24-hr
rainfallLabel
min0.00Start Time
min6.00Increment
min1,440.00End Time
years2Return Event
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth(in)Depth(in)Depth(in)Depth(in)Depth(in)Time(min)
0.00.00.00.00.00.00
0.00.00.00.00.030.00
0.00.00.00.00.060.00
0.10.10.10.00.090.00
0.10.10.10.10.1120.00
0.10.10.10.10.1150.00
0.10.10.10.10.1180.00
0.10.10.10.10.1210.00
0.10.10.10.10.1240.00
0.20.20.20.20.1270.00
0.20.20.20.20.2300.00
0.20.20.20.20.2330.00
0.20.20.20.20.2360.00
0.30.30.30.20.2390.00
0.30.30.30.30.3420.00
0.30.30.30.30.3450.00
0.40.40.40.30.3480.00
0.40.40.40.40.4510.00
Page 13 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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6
2
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 2 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
0.50.50.50.40.4540.00
0.60.50.50.50.5570.00
0.60.60.60.60.6600.00
0.70.70.70.70.6630.00
0.90.80.80.80.7660.00
1.21.11.00.90.9690.00
2.12.01.91.81.5720.00
2.22.22.22.12.1750.00
2.32.32.32.32.2780.00
2.42.42.42.42.4810.00
2.52.52.52.42.4840.00
2.62.52.52.52.5870.00
2.62.62.62.62.6900.00
2.72.62.62.62.6930.00
2.72.72.72.72.7960.00
2.72.72.72.72.7990.00
2.82.72.72.72.71,020.00
2.82.82.82.82.81,050.00
2.82.82.82.82.81,080.00
2.82.82.82.82.81,110.00
2.82.82.82.82.81,140.00
2.92.92.92.92.91,170.00
2.92.92.92.92.91,200.00
2.92.92.92.92.91,230.00
2.92.92.92.92.91,260.00
2.92.92.92.92.91,290.00
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F
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6
3
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: Type III 24-hr Northampton
Return Event: 2 yearsSubsection: Time-Depth Curve
CUMULATIVE RAINFALL (in)
Output Time Increment = 6.00 min
Time on left represents time for first value in each row.
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Depth
(in)
Time
(min)
3.03.02.92.92.91,320.00
3.03.03.03.03.01,350.00
3.03.03.03.03.01,380.00
3.03.03.03.03.01,410.00
(N/A)(N/A)(N/A)(N/A)3.01,440.00
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F
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6
4
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-A
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
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6
5
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-A
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
Page 17 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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6
6
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-B
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
Page 18 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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6
7
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-B
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
Page 19 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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6
8
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-C
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
Page 20 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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6
9
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-C
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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7
0
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-D
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
Page 22 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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7
1
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-D
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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7
2
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-F
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
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7
3
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-F
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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4
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-G
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
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7
5
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-G
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
Page 27 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-H
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
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7
7
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-H
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
Page 29 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-J
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
Page 30 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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7
9
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-J
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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8
0
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-K
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
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F
-
8
1
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-K
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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8
2
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-Pond B
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
Page 34 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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[08.11.01.56]Bentley Systems, Inc. Haestad Methods Solution CenterNorthampton Proposed.ppc
F
-
8
3
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-Pond B
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
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F
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8
4
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-Pond J
Return Event: 2 yearsSubsection: Time of Concentration Calculations
Time of Concentration Results
Segment #1: User Defined Tc
min5.00Time of Concentration
Time of Concentration (Composite)
min5.00Time of Concentration
(Composite)
Page 36 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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[08.11.01.56]Bentley Systems, Inc. Haestad Methods Solution CenterNorthampton Proposed.ppc
F
-
8
5
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-Pond J
Return Event: 2 yearsSubsection: Time of Concentration Calculations
==== User Defined
Value entered by userTc =
Tc= Time of concentration, hoursWhere:
Page 37 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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F
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6
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-A
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.084,89398.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.038,36161.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
55.0000.00.02,90855.000Woods - good - Soil B
85.759(N/A)(N/A)126,162(N/A)COMPOSITE AREA & WEIGHTED CN --->
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F
-
8
7
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-B
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.073,88798.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.032,88861.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
86.604(N/A)(N/A)106,775(N/A)COMPOSITE AREA & WEIGHTED CN --->
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F
-
8
8
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-C
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.062,43898.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.049,31061.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
81.673(N/A)(N/A)111,748(N/A)COMPOSITE AREA & WEIGHTED CN --->
Page 40 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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[08.11.01.56]Bentley Systems, Inc. Haestad Methods Solution CenterNorthampton Proposed.ppc
F
-
8
9
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-D
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.05,95698.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
98.000(N/A)(N/A)5,956(N/A)COMPOSITE AREA & WEIGHTED CN --->
Page 41 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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[08.11.01.56]Bentley Systems, Inc. Haestad Methods Solution CenterNorthampton Proposed.ppc
F
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0
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-F
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.013,96998.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
48.0000.00.024,91648.000Brush - brush, weed, grass mix - good - Soil B
61.0000.00.027,10061.000Pasture, grassland, or range - good - Soil B
58.0000.00.031,20558.000Woods - grass combination - good - Soil B
62.022(N/A)(N/A)97,190(N/A)COMPOSITE AREA & WEIGHTED CN --->
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604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-G
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.0154,96598.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.093,19961.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
84.104(N/A)(N/A)248,164(N/A)COMPOSITE AREA & WEIGHTED CN --->
Page 43 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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2
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-H
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.025,01398.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.04,68561.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
92.163(N/A)(N/A)29,698(N/A)COMPOSITE AREA & WEIGHTED CN --->
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3
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-J
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.016,72098.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
61.0000.00.04,22461.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
90.538(N/A)(N/A)20,944(N/A)COMPOSITE AREA & WEIGHTED CN --->
Page 45 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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4
604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-K
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
98.0000.00.02,97498.000Impervious Areas - Paved parking lots, roofs,
driveways, Streets and roads - Soil B
48.0000.00.028,65548.000Brush - brush, weed, grass mix - good - Soil B
58.0000.00.054,71358.000Woods - grass combination - good - Soil B
56.059(N/A)(N/A)86,342(N/A)COMPOSITE AREA & WEIGHTED CN --->
Page 46 of 5027 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA
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604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-Pond B
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
61.0000.00.035,47161.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
61.000(N/A)(N/A)35,471(N/A)COMPOSITE AREA & WEIGHTED CN --->
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604597 - Proposed Drainage Model
Storm Event: 2-year, 24-hr rainfallLabel: PR-Pond J
Return Event: 2 yearsSubsection: Runoff CN-Area
Runoff Curve Number Data
Adjusted CNUC
(%)
C
(%)
Area
(ft²)
CNSoil/Surface Description
61.0000.00.021,54761.000Open space (Lawns,parks etc.) - Good condition; grass
cover > 75% - Soil B
61.000(N/A)(N/A)21,547(N/A)COMPOSITE AREA & WEIGHTED CN --->
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7
Type III 24-hr Northampton (Time-Depth Curve, 2
years)...13, 14, 15
Type III 24-hr Northampton (Time-Depth Curve, 100
years)...7, 8, 9
Type III 24-hr Northampton (Time-Depth Curve, 10
years)...10, 11, 12
T
PR-Pond J (Time of Concentration Calculations, 2years)...36, 37
PR-Pond J (Runoff CN-Area, 2 years)...48
PR-Pond B (Time of Concentration Calculations, 2
years)...34, 35
PR-Pond B (Runoff CN-Area, 2 years)...47
PR-K (Time of Concentration Calculations, 2 years)...32,
33
PR-K (Runoff CN-Area, 2 years)...46
PR-J (Time of Concentration Calculations, 2 years)...30, 31
PR-J (Runoff CN-Area, 2 years)...45
PR-H (Time of Concentration Calculations, 2 years)...28,
29
PR-H (Runoff CN-Area, 2 years)...44
PR-G (Time of Concentration Calculations, 2 years)...26,
27
PR-G (Runoff CN-Area, 2 years)...43
PR-F (Time of Concentration Calculations, 2 years)...24,
25
PR-F (Runoff CN-Area, 2 years)...42
PR-D (Time of Concentration Calculations, 2 years)...22,
23
PR-D (Runoff CN-Area, 2 years)...41
PR-C (Time of Concentration Calculations, 2 years)...20,
21
PR-C (Runoff CN-Area, 2 years)...40
PR-B (Time of Concentration Calculations, 2 years)...18,19
PR-B (Runoff CN-Area, 2 years)...39
PR-A (Time of Concentration Calculations, 2 years)...16,
17
PR-A (Runoff CN-Area, 2 years)...38
P
Master Network Summary...2, 3, 4, 5, 6
M
604597 - Proposed Drainage Model
Index
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604597 - Proposed Drainage Model
Type III 24-hr Northampton (Time-Depth Curve, 2
years)...13, 14, 15
Type III 24-hr Northampton (Time-Depth Curve, 100years)...7, 8, 9
Type III 24-hr Northampton (Time-Depth Curve, 10
years)...10, 11, 12
T
PR-Pond J (Time of Concentration Calculations, 2years)...36, 37
PR-Pond J (Runoff CN-Area, 2 years)...48
PR-Pond B (Time of Concentration Calculations, 2
years)...34, 35
PR-Pond B (Runoff CN-Area, 2 years)...47
PR-K (Time of Concentration Calculations, 2 years)...32,
33
PR-K (Runoff CN-Area, 2 years)...46
PR-J (Time of Concentration Calculations, 2 years)...30, 31
PR-J (Runoff CN-Area, 2 years)...45
PR-H (Time of Concentration Calculations, 2 years)...28,
29
PR-H (Runoff CN-Area, 2 years)...44
PR-G (Time of Concentration Calculations, 2 years)...26,
27
PR-G (Runoff CN-Area, 2 years)...43
PR-F (Time of Concentration Calculations, 2 years)...24,25
PR-F (Runoff CN-Area, 2 years)...42
PR-D (Time of Concentration Calculations, 2 years)...22,
23
PR-D (Runoff CN-Area, 2 years)...41
PR-C (Time of Concentration Calculations, 2 years)...20,
21
PR-C (Runoff CN-Area, 2 years)...40
PR-B (Time of Concentration Calculations, 2 years)...18,19
PR-B (Runoff CN-Area, 2 years)...39PR-A (Time of Concentration Calculations, 2 years)...16,17PR-A (Runoff CN-Area, 2 years)...38PMaster Network Summary...2, 3, 4, 5, 6M
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Stormwater Report
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
ATTACHMENT G-
Test Pit Logs
Pages G-1 - G-8
PROJECT TEST PIT NO.
SHEET 1 of 2
FILE NO.
CHKD BY
Engineer Make Kobelco Ground El.
Contractor Model SK55SRX Datum
Operator Capacity ~5.7 Cubic Feet Time Start 12:45
Weather Reach ~12 feet Date 2/1/2017
Depth Strata
Below Change &Subsurface Description Excavation Boulder
Grade Water Effort Qty/Class(ft)Level
3
4
7
8
10
11
12
13
14
15
Notes:WATER SYMBOLS
Groundwater
Estimated Seasonal High Groundwater
BOULDER CLASS PROPORTIONS USED EXCAVATION EFFORT
12" - 24" A 0-10% Trace E = Easy
N 24" - 36" B 10-20% Little M = Moderate
>36" C 20-35% Some D = Difficult
35-50% And
Snow, 30°'s
TEST PIT LOG
TP-1
Interstate 91 and Route 9
Intersection Reconstruction 92470.00
Northampton, Massachusetts Jorge Fuentes
Patrick Clarke ~135
New England Boring NAVD88
John Galvin
USDA
Textural
Class
1
TOPSOIL Dark brown, SILT, trace fine to medium Sand, moist (TOPSOIL).
-
-
FILL
~14'
~4'
E Loamy
Sand
G-1) Light brown, fine SAND, some Silt, dry (FILL). [Laboratory
Analysis Performed: Grain Size Analysis (Sieve & Hydrometer) -
Gravel = 0.0%, Sand = 73.2%, Silt & Clay = 26.8%].
Groundwater table not encountered. Test pit terminated at
approximately 10 feet below ground surface.
1.) Test pit backfilled with excavated soils and compacted with excavator bucket
at ground surface.
2.) Ground surface elevation interpolated from provided plans and should be
considered approximate.
2
5
6
9
0.3'
10'
G - 1
PROJECT TEST PIT NO.
SHEET 2 of 2
FILE NO.
CHKD BY
Engineer Make Kobelco Ground El.
Contractor Model SK55SRX Datum
Operator Capacity ~5.7 Cubic Feet Time Start 12:45
Weather Reach ~12 feet Date 2/1/2017
Notes:
N
Snow, 30°'s
TEST PIT LOG
TP-1
Interstate 91 and Route 9
Intersection Reconstruction 92470.00
Northampton, Massachusetts Jorge Fuentes
Patrick Clarke ~135
New England Boring NAVD88
John Galvin
1.) Photo of in-progress TP-1.
~14'
~4'
TOPSOIL
G-1
G - 2
PROJECT TEST PIT NO.
SHEET 1 of 2
FILE NO.
CHKD BY
Engineer Make Kobelco Ground El.
Contractor Model SK55SRX Datum
Operator Capacity ~5.7 Cubic Feet Time Start 11:45
Weather Reach ~12 feet Date 2/1/2017
Depth Strata
Below Change &Subsurface Description Excavation Boulder
Grade Water Effort Qty/Class(ft)Level
3
4
7
8
10
11
12
13
14
15
Notes:WATER SYMBOLS
Groundwater
Estimated Seasonal High Groundwater
BOULDER CLASS PROPORTIONS USED EXCAVATION EFFORT
12" - 24" A 0-10% Trace E = Easy
24" - 36" B 10-20% Little M = Moderate
N >36" C 20-35% Some D = Difficult
35-50% And
Snow, 30°'s
TEST PIT LOG
TP-2
Interstate 91 and Route 9
Intersection Reconstruction 92470.00
Northampton, Massachusetts Jorge Fuentes
Patrick Clarke ~122
New England Boring NAVD88
John Galvin
USDA
Textural
Class
1
TOPSOIL Dark brown, SILT, trace fine to medium Sand, moist (TOPSOIL).
-
-
FILL
E
MG-1) Brown, fine to coarse SAND, some fine to coarse Gravel,
little Silt, very few asphalt particles, very few roots, moist (FILL).
G-2) Brown, fine to coarse SAND, some fine to coarse Gravel,
trace Silt, very few cobbles, dry to wet (FILL). Perched water
infiltrating corner of excavation at depth of approximately 5 feet
below ground surface.
G-3) Brown, SILT & CLAY, trace fine Sand, wet (FILL).
[Laboratory Analysis Performed: Grain Size Analysis (Sieve &
Hydrometer) - Gravel = 0.0%, Sand = 2.1%, Silt & Clay = 97.9%].
Sandy
Loam
Silt Loam
Gravelly
Sand
Gravelly,
Loamy Sand
E
G-4) Brown, fine SAND and Silt, dry (FILL).
Groundwater table not encountered. Test pit terminated at
approximately 10 feet below ground surface.
1.) Test pit backfilled with excavated soils and compacted with excavator bucket
at ground surface.
2.) Ground surface elevation interpolated from provided plans and should be
considered approximate.
~13'
~3'
2
5
6
9
0.3'
10'
1.5'
5.5'
8.5'
G - 3
PROJECT TEST PIT NO.
SHEET 2 of 2
FILE NO.
CHKD BY
Engineer Make Kobelco Ground El.
Contractor Model SK55SRX Datum
Operator Capacity ~5.7 Cubic Feet Time Start 11:45
Weather Reach ~12 feet Date 2/1/2017
Notes:
N
Snow, 30°'s
TEST PIT LOG
TP-2
Interstate 91 and Route 9
Intersection Reconstruction 92470.00
Northampton, Massachusetts Jorge Fuentes
Patrick Clarke ~122
New England Boring NAVD88
John Galvin
1.) Photo of completed TP-2.
~13'
~3'
TOPSOIL
G-1
G-3
G-2
G-4
Very few cobbles
Perchedwater infiltration
G - 4
PROJECT TEST PIT NO.
SHEET 1 of 2
FILE NO.
CHKD BY
Engineer Make Kobelco Ground El.
Contractor Model SK55SRX Datum
Operator Capacity ~5.7 Cubic Feet Time Start 10:30
Weather Reach ~12 feet Date 2/1/2017
Depth Strata
Below Change &Subsurface Description Excavation Boulder
Grade Water Effort Qty/Class(ft)Level
3
4
7
8
10
11
12
13
14
15
Notes:WATER SYMBOLS
Groundwater
Estimated Seasonal High Groundwater
BOULDER CLASS PROPORTIONS USED EXCAVATION EFFORT
12" - 24" A 0-10% Trace E = Easy
24" - 36" B 10-20% Little M = Moderate
N >36" C 20-35% Some D = Difficult
35-50% And
Snow, 30°'s
TEST PIT LOG
TP-3
Interstate 91 and Route 9
Intersection Reconstruction 92470.00
Northampton, Massachusetts Jorge Fuentes
Patrick Clarke ~127
New England Boring NAVD88
John Galvin
USDA
Textural
Class
1
TOPSOIL Dark brown, SILT, some fine to coarse Sand, trace fine Gravel, moist (TOPSOIL).-
G-1) Brown, fine to coarse SAND, little fine to coarse Gravel,
trace Silt, very few cobbles, dry (FILL).
E
G-3) Brown, fine to coarse SAND, some fine to coarse Gravel,
trace Silt, dry (FILL).
9
-FILL
Sand
Gravelly
Sand
5
6
2
1.) Test pit backfilled with excavated soils and compacted with excavator bucket
at ground surface.
2.) Ground surface elevation interpolated from provided plans and should be
considered approximate.
~17.5'
~2.5'
Silt Loam
Groundwater table not encountered. Test pit terminated at
approximately 10 feet below ground surface.
0.3'
7.3'
8'
10'
G-2) Gray to dark gray, Clayey SILT, some fine to medium Sand, very few roots,
organic-like odor, dry (FILL). [Laboratory Analysis Performed: Grain Size Analysis
G - 5
PROJECT TEST PIT NO.
SHEET 2 of 2
FILE NO.
CHKD BY
Engineer Make Kobelco Ground El.
Contractor Model SK55SRX Datum
Operator Capacity ~5.7 Cubic Feet Time Start 10:30
Weather Reach ~12 feet Date 2/1/2017
Notes:
N
Snow, 30°'s
TEST PIT LOG
TP-3
Interstate 91 and Route 9
Intersection Reconstruction 92470.00
Northampton, Massachusetts Jorge Fuentes
Patrick Clarke ~127
New England Boring NAVD88
John Galvin
1.) Photo of completed TP-3.
~17.5'
~2.5'
TOPSOIL
G-1
G-3
G-2
G - 6
PROJECT TEST PIT NO.
SHEET 1 of 2
FILE NO.
CHKD BY
Engineer Make Kobelco Ground El.
Contractor Model SK55SRX Datum
Operator Capacity ~5.7 Cubic Feet Time Start 9:30
Weather Reach ~12 feet Date 2/1/2017
Depth Strata
Below Change &Subsurface Description Excavation Boulder
Grade Water Effort Qty/Class(ft)Level
3
4
7
8
10
11
12
13
14
15
Notes:WATER SYMBOLS
Groundwater
Estimated Seasonal High Groundwater
BOULDER CLASS PROPORTIONS USED EXCAVATION EFFORT
12" - 24" A 0-10% Trace E = Easy
24" - 36" B 10-20% Little M = Moderate
N >36" C 20-35% Some D = Difficult
35-50% And
Snow, 30°'s
USDA
Textural
Class
Patrick Clarke ~134
New England Boring NAVD88
John Galvin
TEST PIT LOG
TP-4
Interstate 91 and Route 9
Intersection Reconstruction
Northampton, Massachusetts Jorge Fuentes
92470.00
1.) Test pit backfilled with excavated soils and compacted with excavator bucket
at ground surface.
2.) Ground surface elevation interpolated from provided plans and should be
considered approximate.
~13'
~4'
9
5
6
FILL
Dark brown, SILT, trace fine to medium Sand, moist (TOPSOIL).
G-1) Brown/gray, fine to coarse SAND and Clayey Silt, little fine
to coarse Gravel, very few cobbles, very few roots, moist (FILL).
Groundwater table not encountered. Test pit terminated at
approximately 8.8 feet below ground surface.
G-2) Reddish brown, fine to medium SAND, some Silt, trace fine Gravel, moist
(FILL). [Laboratory Analysis Performed: Grain Size Analysis (Sieve & Hydrometer)
- Gravel = 2.9%, Sand = 73.1%, Silt & Clay = 24.0%].
G-1) Brown, fine to coarse SAND and Clayey Silt, little fine to coarse
Gravel, very few cobbles, very few roots, moist (FILL).
G-2) Reddish brown, fine to medium SAND, some Silt, trace fine
to coarse Gravel, moist (FILL).
G-3) Reddish brown, fine to coarse SAND, little fine to coarse
Gravel, trace Silt, dry (FILL).
G-4) Reddish brown, fine to coarse SAND and fine to coarse
Gravel, trace Silt, dry (FILL).
-
Loam
Sandy
Loam
2
TOPSOIL
1
-
D
E
Very
Gravelly
Sand
M Loam
M
D Sandy
Loam
Gravelly
Sand
0.3'
2.5'
4'
4.8'
5.8'
7'
8.8'
G - 7
PROJECT TEST PIT NO.
SHEET 2 of 2
FILE NO.
CHKD BY
Engineer Make Kobelco Ground El.
Contractor Model SK55SRX Datum
Operator Capacity ~5.7 Cubic Feet Time Start 9:30
Weather Reach ~12 feet Date 2/1/2017
Notes:
N
Snow, 30°'s
TEST PIT LOG
TP-4
Interstate 91 and Route 9
Intersection Reconstruction
Northampton, Massachusetts Jorge Fuentes
Patrick Clarke ~134
New England Boring NAVD88
John Galvin
92470.00
1.) Photo of completed TP-4.
~13'
~4'
G-2
TOPSOIL
G-1
G-3
G-1
G-2
G-4
G - 8
Stormwater Report
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
ATTACHMENT H-
Long Term Pollution Prevention Plan (LTPPP)
Pages H-1 - H-4
H - 1
LTPPP
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
Long Term Pollution Prevention Plan (LTPPP)
Highway Plans
The highway plans and details include erosion and sediment control measures that will be installed.
Materials Covered
The following materials or substances are expected to be present onsite during construction.
Concrete/Additives/Wastes
Petroleum based products
Solid and construction wastes
Sanitary wastes
Materials Management Practices
The following material management practices will be implemented onsite during construction to
reduce the risk of spills or other accidental exposure of materials and substances to stormwater
runoff. The contractor’s superintendent will be responsible for ensuring that these procedures are
followed.
1. Good Housekeeping
The following good housekeeping practices will be implemented onsite during construction.
a. An effort will be made to store only enough products required to do the job.
b. All materials onsite will be stored in a neat and orderly manner. If possible, materials will be
stored under a roof or in a containment area. At a minimum, all containers will be covered
with proper lids when not in use, and drip pans will be provided under all dispensers.
c. Products will be kept in their original containers, with the original manufacturer’s label in
legible condition.
d. Substances will not be mixed with one another unless recommended by the manufacturer.
e. Whenever possible, all products will be used before disposing the container.
f. Manufacturer’s recommendations for proper use and disposal will be followed.
g. The Contractor’s superintendent will be responsible for daily inspections to ensure proper
use and disposal of materials.
2. Hazardous Substances
The following practices will be implemented to reduce the risks associated with hazardous
substances. Material Safety Data Sheets (MSDS’s) will be obtained for each product onsite that has
hazardous properties, and used for the proper management of potential wastes that may result from
these products. Each employee who must handle a hazardous substance will be instructed on the
use of MSDS sheets and the specific information in the applicable MSDS for the product he/she is
using, particularly regarding spill control techniques.
a. Products will be kept in original containers with the original labels in legible condition.
H - 2
LTPPP
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
b. Original labels and MSDS’s will be procured and used for each product.
c. If surplus product must be disposed, it will be disposed according to manufacturer’s and
local/state/federal methods for proper disposal.
3. Hazardous Waste
All hazardous waste must be properly identified and handled in accordance with all applicable
hazardous waste standards, including the storage, transport and disposal of the hazardous wastes.
There are significant penalties for the improper handling of hazardous wastes. It is important that
the site superintendent seek appropriate assistance in making the determination of whether a
substance or material is a hazardous waste.
4. Product Specific Practices
The following product specific practices will be implemented on the job site.
a. Petroleum Products—All onsite vehicles will be monitored for leaks and receive regular
preventive maintenance to reduce the chance of leakage. Petroleum products will be stored
in tightly sealed containers that are clearly labeled.
b. Concrete Wastes—Concrete trucks will be allowed to wash out or discharge surplus
concrete or drum wash water on the project site, but only in specifically designated diked
and impervious washout areas, which are prepared to prevent contact between the
concrete wash and stormwater. Waste generated from concrete wash water must not be
allowed to flow into drainage ways, inlets, receiving waters or any location other than the
designated concrete washout area. Waste concrete may be poured into forms to make
riprap or other useful concrete products. Concrete washouts must be located at least 100
feet from drainage ways, inlets and surface waters. The hardened residue from the concrete
washout areas will be disposed in the same manner as other non-hazardous construction
waste.
5. Solid and Construction Wastes
All waste materials will be collected and transported to an appropriate solid waste disposal area.
6. Sanitary Wastes
A minimum of one portable sanitary unit will be provided for every ten (10) workers on the site. All
sanitary waste materials will be collected from the portable units at least weekly by a licensed
portable facility provider in complete compliance with local and state regulations. All sanitary waste
units will be located in an area where the likelihood of the unit contributing to stormwater
discharges is negligible. If necessary to prevent wastes from contributing to stormwater discharges,
additional containment BMPs must be implemented, such as gravel bags or specially designated
plastic skid containers around the base.
7. Contaminated Soils
Any contaminated soils, either resulting from spills of hazardous substances or discovered during the
course of construction, must be contained and cleaned up immediately in accordance with the
procedures outlined in the Materials Management Plan and in accordance with applicable state and
federal regulations. Contaminated soils not resulting from construction activities, which pre-existed
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LTPPP
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
construction activities and are discovered by virtue of construction activities, should be reported in
the same manner as spills, but with sufficient information to specify that an existing condition
discovery is being reported. If there is a release that occurs by virtue of the discovery of existing
contamination and it otherwise meets the requirements for a reportable spill, then the release must
be reported as a spill.
Spill Prevention Procedures
The Contractor will train all personnel in the proper handling and cleanup of spilled hazardous
substances or oil. In order to prevent or minimize the potential for a spill of hazardous substances
or oil to come into contact with stormwater, the following steps will be implemented.
1. All hazardous substances, such as oil, pesticides, petroleum products, fertilizers, detergents,
construction chemicals, will be stored in a secure location.
2. Only the minimum practical quantity of such materials will be kept at the project site.
3. The contractor must have a readily available spill prevention kit and materials on site at all times.
The contractor’s onsite spill prevention storage location shall be stocked at all times with a
suitable quantity of absorbent and containment materials to address multiple spills in a single
day. At a minimum the spill prevention storage location shall include the following materials:
Absorbent pads
Absorbent boom
55-gallon drums with sealable lid
Speedy-dry
Goggles
Plastics or trash containers, etc.
4. Manufacturer’s recommended methods for spill cleanup will be clearly posted, and site
personnel will be trained regarding these procedures and the location of the cleanup supplies.
5. It is the contractor’s responsibility to ensure that all hazardous waste discovered or generated
at the project site is disposed properly by a licensed hazardous material disposal facility.
Spill Response Procedures
In the event of a spill of hazardous substances or oil, the following procedures must be followed:
1. All measures must be taken to contain and abate the spill and to prevent the discharge of the
hazardous substance or oil to stormwater, or off-site. The spill area must be kept well ventilated
and personnel must wear appropriate protective clothing to prevent injury from contact with
the hazardous substances.
2. For spills of less than five (5) gallons of material, proceed with source control and containment,
clean-up with absorbent materials or other applicable means unless an imminent hazard or other
circumstances dictate that the spill should be treated by a professional emergency response
contractor.
3. For spills greater than five (5) gallons of material, immediately contact the MA DEP Hazardous
Waste Incident Response Group, and an approved emergency response contractor. Provide
information on the type of material spilled, the location of the spill, the quantity spilled, and the
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Improvements on I-91 Interchange 19
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Northampton, MA
time of the spill to the emergency response contractor or coordinator, and proceed with
prevention, containment and/or clean-up.
4. If there is a Reportable Quantity (RQ) release during the construction period, then the National
Response Center will be notified immediately. Within 14 days a report will be submitted to the
EPA regional office describing the release, the date and circumstances of the release and the
steps taken to prevent another release. This Stormwater Pollution Prevention Plan must be
updated to reflect any such steps or actions taken and measures to prevent the same from
reoccurring.
5. The contractor’s superintendent will be the spill prevention and response coordinator. He will
designate the individuals who will receive spill prevention and response training. These
individuals will each become responsible for a particular phase of prevention and response. The
names of these personnel will be posted in the material storage area and in the office trailer
onsite.
Illicit Discharge Statement-Control of Non-Stormwater Discharges
Certain types of discharges are allowable under the U.S. EPA Construction General Permit, and it is
the intent of this LTPPP to allow such discharges. These types of discharges will be allowed under
the conditions that no pollutants will be allowed to come in contact with that water prior to or
after its discharge. The control measures that have been outlined previously in this LTPPP will be
followed strictly to ensure that no contamination of these non-stormwater discharges takes place.
Stormwater Report
I-91/Route 9 & Damon Road
Interchange Improvements
Northampton, MA
ATTACHMENT I-
Operation and Maintenance Plan (O&M Plan)
Pages I-1 - I-2
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Operation and Maintenance Plan
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
Stormwater Management Operation and Maintenance Plan
(O&M Plan)
Description of the Stormwater Management System
The stormwater management system for this project collects runoff from the roadways for
treatment prior to discharge to water bodies. The system includes the following features: pavement
edging, deep sump catch basins, pipes, drop inlets, manholes, paved waterway, flared end sections,
and sediment forebays with associated infiltration basins.
During Construction
The site contractor, who will be selected by the standard bidding process established by the
Massachusetts Department of Transportation (MassDOT), will be responsible for all operation and
maintenance (O&M) from the initial ground disturbance through final stabilization and project
closeout. Those responsibilities will include:
1. Construct all erosion and sedimentation control measures in accordance with MassDEP
Erosion and Sediment Control Guidelines for Urban and Suburban Areas dated May 2003
and the U.S. EPA Developing Your Stormwater Pollution Prevention Plan dated May 2007.
2. Install erosion and sediment control measures prior to any ground disturbance.
Continuously maintain the erosion and sediment control measures so that they remain
functional until final stabilization is established.
3. Install perimeter erosion and sediment controls, such as compost filter tubes, around all
stockpiles.
4. Seed or mulch stockpiles and other disturbed or exposed areas for temporary stabilization,
prior to exposure of fourteen days or more.
5. At any portion of the site where construction activities have permanently ceased, or where
final grades are reached, implement stabilization practices within three days.
6. Conduct earthwork activity so that runoff is directed away from resources areas.
7. Relocate temporary drainage swales and sediment traps as construction progresses, so that
they continue to provide their intended function throughout all phases of construction.
8. Inspect all erosion and sedimentation control measures at least every seven days, and after
each rainfall event that exceeds a quarter inch. If the function of any feature is found to be
compromised, take action within three days to clean, repair, or replace the compromised
erosion and sedimentation control measure. Adhere to the Stormwater Pollution
Prevention Plan (SWPPP).
9. Upon completion of all work, inspect all catch basins and remove all accumulated sediment
and trash debris.
10. Meet or exceed MassDOT’s specifications.
11. As the project progresses and site drainage conditions change, relocate or augment the
erosion and sediment control measures to meet or exceed the minimum measures shown
on the highway plans and details.
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Operation and Maintenance Plan
Improvements on I-91 Interchange 19
at Route 9 and Damon Road
Northampton, MA
Post Construction
MassDOT will be responsible for post-construction O&M activities, which will be undertaken at a
statewide programmatic level under the State’s highway operation and maintenance program. In
addition to MassDOT’s standard O&M activities, MassDOT will implement the following
stormwater maintenance plan:
Inspections
Check deep sump catch basins, manholes, paved waterways, drop inlets, flared end sections,
headwalls, sediment forebays, and overflow spillways for blockage, erosion, and structural
deficiency.
Remove trash, debris, and decaying vegetation. Clear blockages.
Repair eroded channels or holes. Add protection, as necessary to prevent further erosion.
Conduct inspections according to the frequencies outlined below.
First Year Post-Construction
Conduct inspections at least once per season.
Re-vegetate poorly established areas as necessary.
After the First Year Post-Construction
Conduct inspections every six months.
Following two years of monitoring that produce no special cleaning or repair, reduce the
inspection frequency to annual inspections.
Remove accumulated sediment that exceeds six inches at least annually from all catch basins,
drop inlets, paved waterways, sediment forebays, infiltration basins and outlet control
structures.
Clear sediment forebays, and infiltration basins of any vegetation or debris that
compromises its functional storage volume.
Do not use heavy equipment within the infiltration basins. Heavy equipment must remain on
the maintenance shelf.