174343.00 - As-Built Survey Review Letter - Mill River Levee_5-22-20 (2)
May 22, 2020
File No. 01.0174343.00
Mr. David Veleta, P.E. – City Engineer
City of Northampton Department of Public Works
125 Locust Street
Northampton, Massachusetts 01060
Re: Review of Existing As-built Drawings - Mill River Levee System
FEMA Certification/Accreditation Efforts
Northampton, Massachusetts
Dear Mr. Veleta,
In accordance with our contract (WF7-19-2019), GZA is pleased to provide the City of
Northampton Department of Public Works (DPW) this letter summarizing our review of existing
as-built information and our recommendations for supplemental survey information for the Mill
River Levee System. The purpose of this letter is to provide an evaluation of the suitability and
completeness of the existing preliminary as-built survey completed in 2015 relative to
requirements of the FEMA guidelines. This letter is subject to the Limitations provided in
Attachment A.
Detailed “as-built” information is required to support the City’s efforts to obtain levee
certification/accreditation for the Northampton Flood Protection System from the Federal
Emergency Management Agency (FEMA) in accordance with 44 CFR 65.10. For successful
accreditation, FEMA guidelines require that “Data submitted to support that a given levee
system complies with the structural requirements … must be certified by a registered professional
engineer. Also, certified as-built plans of the levee must be submitted.”
REVIEW OF EXISTING AS-BUILT SURVEY INFORMATION
GZA’s evaluation of the existing as-built information for the Mill River Levee System included
review of the following sources:
• A preliminary drawing set entitled “Plan of Land in Northampton, MA,” sheets 1 through
9, dated August 20, 2015, prepared by Northeast Survey Consultants, showing an existing
conditions topographic survey of the Mill River Levee System and Mill River Diversion
Channel;
• Discussions with the City as well as email correspondence with the City dated 12/11/19
and 1/7/20; and
• GZA’s general observations made during our subsurface investigation program
completed between 01/15/20 and 1/22/20.
In general, the marked-up 2015 preliminary as-built drawings prepared by Northeast Survey
Consultants, provided as Attachment B to this letter, appear to be useable to satisfy FEMA’s “as-
built” requirements with some limited additions and refinements, including being finalized and
stamped by a professional land surveyor. GZA and the City have identified missing/incorrect
information from the 2015 survey on the Mill River Levee System, and it is also our
understanding that there have been several specific enhancements/changes that have occurred
May 22, 2020
File No. 01.0174343.00
FEMA Certification/Accreditation Efforts for the Mill River Levee System
Page | 2
Proactive by Design
since the 2015 survey. The missing/incorrect information, specific site changes, and required updated survey locations
include:
• Original baseline/centerline and stationing are missing;
• Spot grades are typically needed about every 300 feet along the levee alignment and on top of the floodwall, but
are missing;
• Surface type (i.e. asphalt, gravel, etc.) are missing from road labels crossing the levee alignment;
• Tree clearing was completed on and adjacent to the levee since the last survey, changing the tree line from what
is shown on the current drawings;
• Parcel data is missing from the properties abutting the levee system and diversion channel;
• The catch basin located in the Smith College maintenance lot near station M14+75 is likely connected to the
adjacent structure shown as a “sewer” manhole, but the connection is missing between the structures;
• The structure shown as a “sewer” manhole near station M14+17 is likely an incorrectly labeled “storm sewer”
manhole;
• Inverts of some critical structures (i.e. drainage structures) shown on original USACE plans are missing;
• The sewer/drain manhole in the Smith College maintenance lot near station M14+75 is potentially connected to
an 8-inch diameter cast iron pipe exiting through the river bank retaining wall at El 120.2 feet, and thus passing
beneath the floodwall, but the connection between the sewer/drain manhole is missing;
• A gas valve and monitoring well in the Smith College maintenance lot near Station M15+00 are incorrect/missing;
• The inverts of the retaining wall outfalls (20-inch diameter and 24-inch diameter) from the West Street Pumping
Station are incorrect/missing;
• The elevation of the abandoned water line at the West Street Pumping Station is missing;
• The propane tank at the West Street Pump Station was replaced;
• Various new underground utility installations have occurred. GZA understands that the City has the exact
locations for such changes and can provide a surveyor with the required information to be able to update the as-
built information as required;
• The 8-inch-diameter drain pipe/fitting through the concrete floodwall located at approximately STA M14+50 has
been abandoned/filled; and
• Various site features have changed within approximately 20 feet of the South Street Drop Structure training walls,
including removal of trees, grading, and installation of new riprap and drainage swales.
RECCOMENDATIONS
Based on our review of the available preliminary as-built survey drawings (2015), as well as the input provided by the
City, GZA recommends performing supplemental survey to acquire additional information along the Mill River Levee
System. We recommend that information pertaining to the missing, incorrect, and enhanced/changed items listed above
be collected, obtained, and/or gathered as necessary. In addition, any new features not listed above (i.e. utilities, signs,
utility poles, traffic signs, hydrants, etc.) within 15 feet of the levee toe should be surveyed. Refer to Attachment B for
the 2015 Connecticut River Levee Survey Drawings with detailed mark-ups of the required survey. The survey information
collected should subsequently be used to update the as-built drawings, which will need to be stamped by a licensed land
surveyor to comply with FEMA requirements.
May 22, 2020
File No. 01.0174343.00
FEMA Certification/Accreditation Efforts for the Mill River Levee System
Page | 3
Proactive by Design
Lastly, the preliminary as-built survey drawings (2015) only extend to approximately 500 feet downstream of the South
Street Bridge along the Diversion Channel. However, the remainder of the Diversion Channel continuing downstream to
the Connecticut River Oxbow is considered by the United States Army Corps of Engineers to be part of the Mill River Flood
Diversion System. This includes the Bridle Path Closure Structure, Bridle Path Overflow Structure, and the Old Springfield
Road Bridge. It is not clear at this time if survey will be required to extend from the South Street Bridge to the Old
Springfield Road Bridge in order to satisfy FEMA’s as-built requirements in accordance with 44 CFR 65.10. However, GZA
will attempt to identify as soon as possible if survey of this area will be required during the Year 2 scope of work.
It should also be recognized that GZA may identify the need for some additional survey work during our remaining Year
1 scope of work. The completion of the supplemental survey is not currently included in our Year 1 scope of work or
budget. However, we will provide a recommendation for the supplemental survey scope of work at the end of our Year
1 scope for inclusion during our Year 2 work. At that time, GZA will prepare a contract amendment for such work as
required.
Please feel free to contact us if you have any questions or comments regarding the content of this letter.
Attachments: Attachment A – Limitations
Attachment B – Marked-Up 2015 Preliminary Mill River Levee Survey Drawings (Sheets 1 through 9)
Very truly yours,
GZA GEOENVIRONMENTAL, INC.
Christopher L. Baker, P.E. Tom Jenkins, P.E.
Project Manager Consultant/Reviewer
Matthew A. Taylor, P.E.
Principal
J:\170,000-179,999\174343\174343-00.CLB\Memos\As-Built Letters\174343.00 - As-Built Survey Review Letter - Mill River Levee_5-22-20.docx
ATTACHMENT A
LIMITATIONS
DAM ENGINEERING REPORT LIMITATIONS
01.0174343.00
Page | 1
April 2012
Proactive by Design
USE OF REPORT
1. GZA GeoEnvironmental, Inc. (GZA) prepared this report on behalf of, and for the exclusive use of The City of Northamton
(Client) for the stated purpose(s) and location(s) identified in the Report. Use of this report, in whole or in part, at other
locations, or for other purposes, may lead to inappropriate conclusions; and we do not accept any responsibility for the
consequences of such use(s). Further, reliance by any party not identified in the agreement, for any use, without our prior
written permission, shall be at that party’s sole risk, and without any liability to GZA.
STANDARD OF CARE
2. Our findings and conclusions are based on the work conducted as part of the Scope of Services set forth in the Report
and/or proposal, and reflect our professional judgment. These findings and conclusions must be considered not as
scientific or engineering certainties, but rather as our professional opinions concerning the limited data gathered during
the course of our work. Conditions other than described in this report may be found at the subject location(s).
3. Our services were performed using the degree of skill and care ordinarily exercised by qualified professionals performing
the same type of services at the same time, under similar conditions, at the same or a similar property. No warranty,
expressed or implied, is made.
SUBSURFACE CONDITIONS
4. If presented, the generalized soil profile(s) and description, along with the conclusions and recommendations provided
in our Report, are based in part on widely-spaced subsurface explorations by GZA and/or others, with a limited number
of soil and/or rock samples and groundwater /piezometers data and are intended only to convey trends in subsurface
conditions. The boundaries between strata are approximate and idealized, and were based on our assessment of
subsurface conditions. The composition of strata, and the transitions between strata, may be more variable and more
complex than indicated. For more specific information on soil conditions at a specific location refer to the exploration
logs. The nature and extent of variations between these explorations may not become evident until further exploration
or construction. If variations or other latent conditions then appear evident, it will be necessary to reevaluate the
conclusions and recommendations of this report.
5. Water level readings have been made in test holes (as described in the Report), monitoring wells and piezometers, at
the specified times and under the stated conditions. These data have been reviewed and interpretations have been
made in this Report. Fluctuations in the groundwater and piezometer levels, however, occur due to temporal or spatial
variations in areal recharge rates, soil heterogeneities, reservoir and tailwater levels, the presence of subsurface utilities,
and/or natural or artificially induced perturbations.
GENERAL
6. The observations described in this report were made under the conditions stated therein. The conclusions presented
were based solely upon the services described therein, and not on scientific tasks or procedures beyond the scope of
described services or the time and budgetary constraints imposed by the Client.
7. In preparing this report, GZA relied on certain information provided by the Client, state and local officials, and other
parties referenced therein available to GZA at the time of the evaluation. GZA did not attempt to independently verify
the accuracy or completeness of all information reviewed or received during the course of this evaluation.
8. Any GZA hydrologic analysis presented herein is for the rainfall volumes and distributions stated herein. For storm
conditions other than those analyzed, the response of the site’s spillway, impoundment, and drainage network has not
been evaluated.
DAM ENGINEERING REPORT LIMITATIONS
01.0174343.00
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April 2012
Proactive by Design
9. Observations were made of the site and of structures on the site as indicated within the report. Where access to portions
of the structure or site, or to structures on the site was unavailable or limited, GZA renders no opinion as to the condition
of that portion of the site or structure. In particular, it is noted that water levels in the impoundment and elsewhere
and/or flow over the spillway may have limited GZA’s ability to make observations of underwater portions of the
structure. Excessive vegetation, when present, also inhibits observations.
10. In reviewing this Report, it should be realized that the reported condition of the dam is based on observations of field
conditions during the course of this study along with data made available to GZA. It is important to note that the
condition of a dam depends on numerous and constantly changing internal and external conditions, and is evolutionary
in nature. It would be incorrect to assume that the present condition of the dam will continue to represent the condition
of the dam at some point in the future. Only through continued inspection and care can there be any chance that unsafe
conditions be detected.
COMPLIANCE WITH CODES AND REGULATIONS
11. We used reasonable care in identifying and interpreting applicable codes and regulations. These codes and regulations
are subject to various, and possibly contradictory, interpretations. Compliance with codes and regulations by other
parties is beyond our control.
12. This scope of work does not include an assessment of the need for fences, gates, no-trespassing signs, repairs to existing
fences and railings and other items which may be needed to minimize trespass and provide greater security for the
facility and safety to the public. An evaluation of the project for compliance with OSHA rules and regulations is also
excluded.
COST ESTIMATES
13. Unless otherwise stated, our cost estimates are for comparative, or general planning purposes. These estimates may
involve approximate quantity evaluations and may not be sufficiently accurate to develop construction bids, or to predict
the actual cost of work addressed in this Report. Further, since we have no control over the labor and material costs
required to plan and execute the anticipated work, our estimates were made using our experience and readily available
information. Actual costs may vary over time and could be significantly more, or less, than stated in the Report.
ADDITIONAL SERVICES
14. It is recommended that GZA be retained to provide services during any future: site observations, explorations,
evaluations, design, implementation activities, construction and/or implementation of remedial measures
recommended in this Report. This will allow us the opportunity to: i) observe conditions and compliance with our
design concepts and opinions; ii) allow for changes in the event that conditions are other than anticipated; iii) provide
modifications to our design; and iv) assess the consequences of changes in technologies and/or regulations.
ATTACHMENT B
MARKED-UP 2015 MILL RIVER LEVEE SURVEY DRAWINGS
SHEETS 1 THROUGH 9
PYNCH
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MILL RIVER DIVERSIONNORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON1 9EXISTINGCONDITIONSA
SHEET 1PRELIMINARY
General Survey Requirements:
1.Add all utilities -GIS data provided by City
2.Add Inverts of Critical Structures (i.e.Drainage
Structures)-reference USACE plans provided by the
City
3.Update Tree lines/Edge of wooded areas
4.Survey all encroachments within 15-feet of the toe
of the levee.Typical encroachments include:Signs,
Utility poles,Hydrants,Equipment,etc.
5.Add spot grades every 300 feet
6.Add Match lines
7.Add centerline stationing
Update grades and
wooded area -
recently cleared and
re-graded
Rip rap placed -
update
Rip rap placed -
update
Update surface type
at all roadway
crossings over the
levee alignment
(typ.throughout)
EAR
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GROVE STREET EARLE STREETMANHAN RAIL TRAIL
ROUTE
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TMILL RIVER DIVERSIONMILL
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GROVE STREET NORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON2 9EXISTINGCONDITIONSA
SHEET 2
PRELIMINARY
Texas Road
MILL
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ETTEXAS ROADMILL RIVER DIVERSIONNORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON3 9EXISTINGCONDITIONSA
SHEET 3
PRELIMINARY
TEX
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MILL RIVER DIVERSIONMILL RIVER DIVERSION
ROU
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T NORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON4 9EXISTINGCONDITIONSA
SHEET 4
PRELIMINARY
TEXAS RO
A
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HEBERT AVENUEMILL RIVER DIVERSIONNORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON5 9EXISTINGCONDITIONSA
SHEET 5
PRELIMINARY
MILL
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IVER
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IVERS
ION
MANHAN RAIL TRAILNORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON6 9EXISTINGCONDITIONSA
SHEET 6PRELIMINARY
Add Survey grades,
encroachments,etc.on Columbia
Gas property to within 15-feet of
floodwall or levee toe of
embankment.Confirm with City
that agreement was made
Survey GV and MW
DMH -Update
drainage
connections as
shownAddelevationand
indicate as
abandoned/filled
Survey the elevation
of the invert of the 8-
inch diameter CI in
the retaining wall
Survey 20-inch
and 24-inch
diameter flap gate
inverts and
abandoned 6-inch
water
Remove Propane Tank
Add new tank
TEXAS RO
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MANHAN RAIL TRAILNORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON7 9EXISTINGCONDITIONSA
SHEET 7
PRELIMINARY
WEST
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MILL
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IVER
D
IVERS
IONMILL RIVER
DIVERSIONNORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON8 9EXISTINGCONDITIONSA
SHEET 8
PRELIMINARY
MILL RIVER DIVERSIONCOLLEGE LANENORTHEAST SURVEY CONSULTANTS116 PLEASANT ST. SUITE 302P.O. BOX 109EASTHAMPTON, MA 01027(413) 203-5144PLAN OF LAND INNORTHAMPTON, MAHAMPSHIRE REGISTRYPREPARED FOR THECITY OF NORTHAMPTON9 9EXISTINGCONDITIONSA
SHEET 9
PRELIMINARY
Check