38A-152 Village Hill North Commons DPW 2018-01-25 (2)a
STORMWATER MANAGEMENT PERMIT
APPLICATION DECISION
City of Northampton
Department of Public Works
Project /Site Name: Villa>?e Hill —North Commons
Project Street or Location / Assessor ID: Olander Drive
Applicant Name: The Community Builders
Applicant Address/Phone: 185 Dartmouth Street Boston MA 02116
Owner Name: Hospital Hill Development LLC c/o MA Development Finance Agency
Owner Address/Phone: 99 High Street, Boston, MA 01469
Application Submission Date: 12/12/2017
THE FOLLOWING ACTION BY THE NORTHAMPTON DEPARTMENT OF PUBLIC
WORKS HAS BEEN TAKEN ON THIS APPLICATION BASED ON INFORMATION
PRESENTED:
Disapproval of the Stormwater Management Permit Application based on a
determination within seven days of the receipt of the application that the
application is administratively incomplete (see attached documentation).
_ Approval of the Stormwater Management Permit Application.
X Approval of the Stormwater Management Permit Application subject to any
conditions, modifications or restrictions required by the Department of
Public Works (see below)
_ Disapproval of the Stormwater Management Permit Application based upon
a determination that the proposed plan, as submitted, does not meet the
purposes set forth in the Northampton Stormwater Management,
Standard Permit Conditions:
1. All clearing, grading, drainage, construction, and development shall be conducted in
strict accordance with the following plans and information submitted with the application
and as amended by any conditions attached to this permit:
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a. Site Plan Review, North Commons, Lot 13A Village Hill, Northampton, MA, Site
Plans, Sheets L.1 -L.13, dated 12/8/2017, stamped by Mark B. Darnold, P.E., The
Berkshire Design Group, Inc.
b. Stormwater Management Report for Village Hill Development by The
Community Builders, Lot 13 A (Map31C, Lot 17) and Lot 20 (Map 38A, Lot
109), Northampton, MA, revised 1/16/2018, stamped by Mark B. Darnold, P.E.,
The Berkshire Design Group, Inc.
2. The Northampton Department of Public Works (DPW) or its authorized representative
shall be provided access to the property to conduct inspections before, during, and after
construction activities as necessary. The applicant shall arrange with the DPW to
schedule the following inspections: Initial Inspection, Erosion Control Inspection, Bury
Inspection, and Final Inspection. The DPW may also conduct random inspections to
ensure effective control of erosion and sedimentation during all phases of construction.
3. The owner shall retain a Project Engineer (the design engineer or another professional
engineer of record in the Commonwealth of Massachusetts) to document the construction
of the proposed stormwater system and site development during all phases of the project.
The Project Engineer shall check elevations, inverts, grading, layout, impervious areas
and other critical aspects of the stormwater system as they are being constructed during
all phases of the project. All proposed changes to the approved stormwater facilities and
site development shall be documented by the Project Engineer and submitted to the DPW
for review and approval by the DPW prior to construction of each phase. At the
completion of the work, including construction of all stormwater management facilities
and landscaping, the applicant shall submit to the DPW as -built plans stamped by a
professional engineer of record in the Commonwealth of Massachusetts and a statement
from a professional engineer of record in the Commonwealth of Massachusetts certifying
that the materials and construction of the stormwater management system was
constructed in accordance with the approved plans and functions as designed. The
preparation of as -built plans requires routine inspections and surveying of stormwater
system components and site work during construction.
4. Annual Reports that are stamped by a Registered Professional Engineer documenting
the actions completed as required by the Operation, Maintenance and Inspection
Agreement shall be submitted to the Northampton Department of Public Works by
October 1st of each year (see Specific Condition 1 below).
5. If construction of the proposed stormwater system has not start
ed within five years of the
issue date of this permit, then the permit will expire and a new permit will be required.
Construction is defined as clearing, grading, excavation, filling, and installation of
drainage structures on the lots specified in this permit.
Specific Permit Conditions:
1. Prior to start
of construction and issuance of any Building Permits, the applicant shall
record an executed Stormwater Operation, Maintenance, and Inspection Agreernent that
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is binding on all subsequent owners of land served by the private stormwater
management facility by recording it in the land records of the Registry of Deeds. The
maintenance schedule and responsibility for maintenance of all components of the
proposed stormwater management system must be adequately specified in Attachment A
to this Agreement. The Proposed Stormwater Management System Operation &
Maintenance Plan "Lot 13" 65 -Unit Apartment Building (Map 31 C, Lot 17) Post -
Construction Operation & Maintenance Schedule submitted as part of the Stormwater
Report dated January 16, 2018 must be revised to the satisfaction of the Northampton
DPW including but not limited to: the Contech CDS unit must be specified and a
maintenance schedule described in accordance with the recommendations of the
manufacturer and cleaning of the unit required at least once per year, the rain gardens will
require inspection and regular replacement of plants and mulch. The DPW can provide
additional guidance on required revisions to the maintenance schedule. Additional
information regarding easements and shared maintenance responsibilities for all
components of the proposed storrnwater management system must be included with the
agreement. The final agreement shall be approved by the Northampton DPW and signed
by the owner and the Mayor of Northampton. The final agreement shall be recorded at
the Registry of Deeds at the owner's expense. Section 281-8 of the Northampton
Stormwater Management Ordinance provides additional guidance for the requirements of
this agreement.
2. -This project will be required to submit one or more Notice of Intent (NOI) to the U.S.
EPA for coverage under the NPDES Stormwater Construction General Permit. A copy of
the final NOI and Stormwater Pollution Prevention Plan (SWPPP) shall be submitted to
the Northampton DPW for approval prior to the start of construction and prior to issuance
of a building permit for each phase of construction. Additional erosion and sediment
control measures are necessary for construction of the drain line and outfall to Detention
Basin 2.
All rain gardens and other non -piped components of the proposed stonnwater system
shall be constructed as proposed and stabilized prior to receiving drainage flows from the
proposed development. Additional erosion and sediment control structures may be
required during construction.
4. Construction plans and specifications shall be submitted to the DPW for approval prior• to
issuance of a building permit and prior to the start of construction. Revisions and
additional information must include the following:
a. The Rain Garden detail, 6/L.5, needs furt
her clarification:
• A "6 -inch perforated drain pipe/tie into CB" for the round inlet structure is
called out in the detail. Is a perforated drain pipe proposed for all 3 rain
gardens and if so the location, material, slope and elevation of the 6 inch
perforated drain pipe for each rain garden should be shown on sheet L.4 of the
plans.
• The detail calls for a 6 inch mulch layer and a 24 inch planting media.
Specifications for the mulch and planting media must be added to the plans
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and must meet the recommendations of the Massachusetts Stormwater
Handbook.
b. A detail for the 4 proposed Drain Inlets should added to the plans.
c. The 6 inch PVC drain is shown from the northwest corner of the building to an
outfall on the slope northwest of the building. Please specify if this is a roof leader
or a foundation drain. The plans should label this, and the proposed stone pad at
the outfall should be sized for the expected velocity of flow.
d. The proposed stone for pipe ends shown in the Flared End & Outlet Protection
detail 7/L.8 must include a specification to install stone to the bottom of the slope.
Anew test pit in the location of the proposed rain gardens should be completed prior to
construction to confirm the soil characteristics and estimated seasonal high ground water
elevation underlying the proposed rain gardens in order to verify their functionality and
separation from groundwater.
6. The proposed drainage system from the site discharges to the previously constructed
drainage system that includes two detention basins and an outfall to the Mill River. The
volume of the existing detention basins has been estimated in the calculations based on
Record Plans for Village Hill Road dated May 2009. The DPW has recently compared
the area of Detention Basin 2 and found a discrepancy between the area of Detention
Basin 2 specified in the drainage calculations and the area of the basin using 2014 lidar
elevation data. Detention Basin 2 appears to have a smaller area and volume than the area
and elevations shown in the Record Plans. Within 60 days of the issuance of this permit,
survey of both Detention Basin 2 and Detention Basin 4 must be completed to confirm
the current capacity of the basins. If the volume of these basins is found to be different
from the volume used in the drainage calculations, within six months of the issuance of
this permit and prior to the start of construction the drainage calculations must be revised
to reflect the new survey information and resubmitted to the DPW for approval.
The applicant has proposed a change to the outlet control structure for Detention Basin 2.
The DPW will not consider approving the proposed change to the outlet control structure
until additional information is provided. First, as discussed in number 6 above, the
volume of the Detention Basins 2 and 4 must be surveyed and confirmed. Additionally,
the drainage calculations that were included in the Drainage Repot referenced above are
based on assumed watershed areas and conceptual development outside of the proposed
area of development. Much of the areas have been developed at this time or have been
approved for development. A letter was provided in the Drainage Report by Gale
Associates dated 1/5/2018 which updates some of the areas of impervious that have been
developed in the Village Hill North Campus. There are some discrepancies between these
impervious area numbers and the area numbers used in the drainage calculations and
there is a gap in the information for the Pecoy Development and detention basins in the
northwest section of the North Campus. Within 6 months of the issuance of this permit,
the drainage calculations for the North Campus must be revised and submitted to the
DPW for review based on existing build -out conditions, approved developments, existing
stormwater systems and any remaining conceptual build out of sites. These revised
drainage calculations must include surveyed volume numbers for all the detention
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structures and must accurately represent the actual stormwater flows as they are currently
understood. Based on the results of these revised calculations, the DPW will consider the
proposed change to the outlet control structure.
8. The
app licanthas stated that due to fine soils and in groundwater it is impossible for a
significant level of recharge on the site. The development of the eastern portion of the
Village Hill North Campus previously permitted and relied on the infiltration from
Detention Basin 2 and 4 to meet the recharge requirements. Since Detention Basin 2 and
4 have been found to hold water, all recharge capacity for these structures has been
eliminated. Prior to issuance of a building permit, the applicant must propose additional
measures on the site to send all roof water to an infiltrating system insofar as it is
feasible.
9. The proposed stonnwater management system is designed to mitigate peak stormwater
flows. If, after construction of the proposed system, the system is found to increase
stormwater flows or pollutants in these flows to adjacent properties, roadways and
stormwater systems, the owner shall redesign and reconstruct the drainage system to
prevent any increased stormwater flows or pollutants in these flows to adjacent
properties, roadways and stormwater systems.
Signature of City Engineer Dat
cc. Planning Board c/o Office of Planning and Development
Building Department
Conservation Commission c/o Office of Planning and Development
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