HomeMy WebLinkAboutPeer Review Memo 2 7.28.2025Comprehensive Environmental Inc. ● Bolton, MA ● Merrimack, NH ● New Britain, CT ● www.ceiengineers.com
Brittany DiRienzo July 28, 2025
Conservation Administrator
Town of Yarmouth
1146 Route 28
South Yarmouth, MA 02664
Re: Peer Review Services
1282 Route 28
South Yarmouth, MA
Dear Ms. DiRienzo:
As requested by the Town of Yarmouth, CEI has completed a technical review of the materials and
information listed below for the proposed development project located at 1282 Route 28 in South
Yarmouth, MA.
Our initial review letter (dated June 27, 2025) focused on elements of the proposed project related
stormwater management design. Updated materials submitted by the Applicant are listed below:
a. Stormwater Report, revision date July 14, 2025, prepared by Choubah Engineering Group.
b. Site Plans, revision date July 15, 2025, prepared by Choubah Engineering Group.
c. Response to Peer Review Comments, date Jul 16, 2025, prepared by Choubah Engineering
Group.
The purpose of this supplemental review is to either ensure that CEI’s initial comments have been
addressed or to provide additional comments. Only initial comments that required a response have been
included. CEI’s initial review comments are below, followed by Choubah Engineering Group (CEG)
responses in italic text, and CEI responses in blue text. Outstanding items have been highlighted yellow.
Stormwater Comments
1. The development proposes three subsurface infiltration systems designed to completely infiltrate
runoff generated from the 100-year storm event, however, the following assessments must be
performed to ensure the system will function properly:
a. Test pit must be performed at the location and soil layer of all proposed infiltration systems to
confirm infiltration capacity. A test pit was not performed at the location of System #1 or #3.
CEG Response: The systems locations have been adjusted and moved as close as is
practical to the location of the test pits for systems 1 and 2. Proposed System 3 is in
proximity of the existing fueling pad and fuel tanks.
COMPREHENSIVE
ENVIRONMENTAL
INCORPORATED
41 Main Street
Bolton, MA 01740
508.281.5160
Comprehensive Environmental Inc. ● Bolton, MA ● Merrimack, NH ● New Britain, CT ● www.ceiengineers.com
July 28, 2025
Page 2
It is not feasible to perform a test pits as the gasoline filling station is still operating. The
test pits for this system is approximately 25’ feet from the system.
A total of 7 test pits were performed within this small site, soil profile and infiltration rates
were consistent for all test pits across the board in all locations. We do not anticipate any
changes to ground elevation or soil infiltration rates. In addition a note has been added to
the drainage plans for the design engineer to inspect bottom of all infiltration systems
during construction and to confirm groundwater elevation and soil infiltration rates are
consistent with design values and to make any adjustment to the systems if needed.
CEI: Comment addressed.
b. A mounding analysis is required when the vertical separation from the bottom of an
exfiltration system to estimated seasonal high groundwater is less than four (4) feet and the
recharge system is proposed to attenuate the peak discharge from a 10-year or higher 24-hour
storm (e.g., 10-year, 25-year, 50-year, or 100-year 24-hour storm). The average separation to
estimated seasonal high groundwater is just below 4 feet (El. 16.11) based on the test pits
provided. The bottom of the stormwater chambers for System #1, 2, & 3 is at El. 20.00.
CEG Response: Bottom of all infiltration systems were raised to elevation 20.15 to provide
4 feet of separation from groundwater elevation at 16.11. A mounding analysis is no longer
needed (refer to revised plans and stormwater report).
CEI: While the chambers were raised to provide 4 feet of separation with groundwater, the
chambers are no longer achieving the minimum cover over the chambers as specified in
provided StormTech SC-740 Chamber detail packet. A minimum of 1.5’ of cover is required
over the chambers and the applicant is now providing 1.35’ for systems #1 and #2 and 1.2’
for system #3.
c. Note, per the Yarmouth Stormwater Regulations, the estimated seasonal high groundwater
elevation must be adjusted using the Cape Cod Commission adjustment method (Technical
Bulletin 92- 001, as amended) in areas to be used for stormwater infiltration.
CEG Response: Mottles was used to establish high groundwater elevation (EL. 16.11) and
therefore no adjustment is needed per the Cape Cod Commission adjustment method (refer
to test pits data).
CEI: Comment addressed.
2. Per the Yarmouth Stormwater Regulations, redevelopment projects must achieve 50% total
phosphorus (TP) and 30% total nitrogen (TN) removal in addition to 80% TSS removal from all
impervious area under post-construction conditions. Please document how the project meets TP
and TN removal requirements in the Stormwater Report.
CEG Response: A 100% removal rate for both Total Phosphorus and Total Nitrogen was
targeted in the design of the infiltration systems on site (refer to Appendix “C” of the revised
Stormwater Report). This is in addition to the pavement sweeping, leaf’s removal and cleaning
of the catch basins to be performed twice per year.
CEI: Comment addressed.
3. Note the following information on the erosion and sediment control plan:
Comprehensive Environmental Inc. ● Bolton, MA ● Merrimack, NH ● New Britain, CT ● www.ceiengineers.com
July 28, 2025
Page 3
a. For the subsurface infiltration systems, accomplish any required excavation with equipment
placed just outside of this area. If the size of the area intended for exfiltration is too large to
accommodate this approach, use trucks with low pressure tires to minimize compaction. Keep
the area above and immediately surrounding the subsurface structure roped off to all
construction vehicles until the final cover is installed (either paving or landscaping).
CEG Response: A note to the Erosion and Sediment Control Plan & Drainage Plan has
been added as suggested (refer to revised plans).
CEI: Comment addressed.
b. Per the Yarmouth Stormwater Regulations, a description of vehicles and equipment fueling
procedures, including how fuels and other vehicle maintenance substances will be stored and
handled during construction.
CEG Response: A fueling detail of construction equipment has been added to the Erosion
Control Details and Notes Sheet #2 as suggested (refer to revised plans).
CEI: Include a note detailing how potentially contaminated crushed stone from the fueling
area shall be disposed of, and spill cleanup materials must be readily accessible in this area.
4. Note the following information in the O&M plan.
a. The proposed Grading and Drainage Plan does not include Infiltration Ditches. If infiltration
ditches are not proposed, the O&M plan should remove this reference in the inspection and
maintenance procedures.
CEG Response: This has been removed as suggested (refer to revised O&M Plan).
CEI: Comment addressed.
b. Restrictions on the application of fertilizers are required per Section 2.05(2)d of the
Yarmouth Stormwater Regulations.
CEG Response: Notes have been added to the O&M Plan as suggested (refer to revised
O&M Plan).
CEI: Comment addressed.
We appreciate the opportunity to provide the Town with peer review services. If you have any questions
or comments regarding this report, please contact me at 774-843-2007 or cosullivan@ceiengineers.com.
Sincerely,
COMPREHENSIVE ENVIRONMENTAL, INC.
Conor O’Sullivan
Project Review Engineer
Pareena Deva, P.E.
Project Manager