24B-079 73 Barrett Street-Hathaway Farms Emergency Certification-2012The
Berkshire
Design
Group, Inc.
To: Sarah LaValley
From: Brian Damold
Date: October 23, 2012
MEMORANDUM
Project: Hathaway Farms
Headwall Removal and Erosion Control Work Conducted
After October 2011 Snowstorm
For your records, the following is a description of the work conducted under the issuance of
an Emergency Certification to remove an existing leaning /falling headwall and correct
erosion issues located at the southeast edge of the Hathaway Farms site.
The original location of the failing headwall and erosion issue is shown on the image below.
The headwall was ready to collapse with any minor disturbance and the channel within the
stream had begun to erode under the drain inlet and along the bank due to the existing
steep side slopes adjacent to the meandering stream. The drain inlet was dilapidated as
well and required some minor work to ensure the stream flow was efficiently entering the
inlet. The headwall was clearly originally installed to provide room for the inlet at its base to
convey water into the large 36" pipe that continues north underneath the parking lot. If the
headwall were to collapse, the drain inlet would like be blocked, causing flooding erosion
in the area as this inlet is the only access to the culvert underneath the parking lot.
Site Location
Lfi
11
Lk
Replacernept
4 Alen Place Northampton, Massachusetts 01060 t413.582.7000 f 413.582.7005 bdg @berkshiredesign.com
The image below shows the original condition of the failing headwall and the erosion
occurring behind it. Note that the headwall appears be secured with only a small
2x4 wood board.
Existina Headwall Erosion
The proposed work that was conducted included the removal of the headwall, the minor
grading and armoring of the side slope areas that had eroded, and securing the loose frame
of the drain inlet with a small bed of mortar on top of the existing structure. The stream
banks are now stabilized and the headwall has been removed to remove the potential of the
structure collapsing and causing detrimental effects to the adjacent properties and the
resource area.
The images on the following page were taken right after the completion of construction and
show the side slopes with armoring, secured drain inlet grate, and the removed headwall.
Note that the stream retains its original flow capacity, but the areas of erosion have been
remedied and protected to ensure the system will continue to function without issue in all
conditions in the future.
Armored Stream Bank With Secured Drain Inlet
Armored Stream Bank
/o=main/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=slavalley
From:Kevin Lake [kevin.l.lake@gmail.com]
Sent:Wednesday, December 21, 2011 4:09 PM
To:Sarah LaValley
Subject:Re: Emergency Certification Check-in
Agree
Kevin
On Wed, Dec 21, 2011 at 3:08 PM, Sarah LaValley <slavalley@northamptonma.gov> wrote:
Hi Kevin-
At the applicant’s request, I went to Hathaway Farms with DPW to look at the parking lot headwall again. The previous requests didn’t
do a good job of showing the real problem, which is not really with the headwall as described, but with the flow direction of the stream.
The stream is undercutting the bank during periods of high flow, which is changing the flow pattern so that water hits the headwall
instead of entering the catchbasin as designed. The stream is essentially choosing the path of least resistance, which is not the 90
degree angle that exists now. (See attached drawing).
The headwall (which also functions as a retaining wall) is stable, but additional heavy flows will create more scour, creating flooding
concerns.
If you agree, I will issue an e-cert to allow only placement of armoring material at the side of the headwall and where the bank is being
undercut, to prevent any winter snowmelt from bypassing the inlet pipe altogether. This is a lot less work than was proposed in the
RDA.
I will add conditions to require cleanout of the grate, which is now impeding flow, and a later NOI for additional work to correct the
headwall design. Although this work is needed now, it is not a long-term solution.
Thanks very much-
Sarah
Sarah I. LaValley
Conservation, Preservation and Land Use Planner
City of Northampton
Office of Planning and Development
210 Main Street, Room 11
Northampton MA, 01060
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