HomeMy WebLinkAboutPeer Review 2.16.23
February 16, 2023
Ms. Brittany DiRienzo, Conservation Administrator
Town of Yarmouth
Yarmouth Town Hall
1146 Route 28
South Yarmouth, MA 02664
Re: Yarmouth Riverwalk Park, Route 28
Technical Stormwater Peer Review - 2
669 Route 28
West Yarmouth, MA 02673
TRC Project No. 526741
Dear Ms. DiRienzo,
TRC has completed a technical stormwater peer review of the response to comments prepared by Beta Inc. The
goal of the review was to determine if the application is technically complete and to evaluate general compliance
with the Yarmouth Stormwater Management Regulations, effective July 1, 2021.
The following additional PDF documents prepared by Beta, Inc were reviewed:
1. Stormwater Management Permit report, revised January 2023.
2. Letters addressed to Ms. Brittany DiRienzo, Conservation Administrator, dated February 2, 2023 and
February 16, 2023.
3. Revised site plan sheets, watershed plans, and watershed data, revised February 15, 2023.
The January 19, 2023 peer review comments are provided in italics below, followed by a review of the response.
Previous comments that have been adequately addressed with no further comment are excluded for brevity.
Yarmouth Conservation Commission Stormwater Management Regulations
Waiver Request
The applicant requests “two waivers… from the by-law” in Section 7.1 of the Stormwater Management Report.
However, the two specific standards for which the waiver is requested are not stated. At least one of the standards
appears to be 2.05(4), which requires stormwater treatment.
1. Each standard for which a waiver is requested should be listed and addressed.
2. The location of Isolated Vegetated Wetland (IVW) 2 should be clarified and identified on the plans. It
appears that the area labeled “Wetland Area 3” on the plans is described as IVW 2 in the report.
3. Details of the “stabilized aggregate walkway” and “reinforced turf” have not been provided in the plans nor
described in the report. It is not clear if these material meet the definition of impervious surface that would
require treatment. Details of both should be included in the plans and the anticipated perviousness of each
should be described in the report.
4. Standard 2.05(4)(d), allowing for offsite mitigation, should be addressed in the waiver request.
Beta states that “Based upon the definition of impervious surface in the bylaw, it is BETA’s interpretation that in
accordance with the bylaw any surface which is not fully vegetated qualifies as impervious.” For this reason a waiver
from Section 2.05, Stormwater Management Performance Standards, has been requested for the “stabilized
aggregate walkway” and “reinforced turf”. The bylaw defines an impervious surface as “Any material or structure
that either prevents or retards the entry of water into the underlying soil or causes water to runoff in greater quantities
or at an increased rate of flow. Common impervious surfaces include, but are not limited to, rooftops, walkways,
patios, driveways, parking lots, storage areas, concrete or asphalt paving, and gravel or dense-graded crushed
stone areas.” Beta states in section 7.1 of the Stormwater Management report that “each of the proposed surface
treatments are considered pervious by other organizations”.
Based on this definition and the description of the “stabilized aggregate walkway” and “reinforced turf” provided by
Beta, it is TRC’s opinion that these surfaces should not be considered impervious and a waiver is not required. In
order to ensure that these surfaces remain permeable, it is recommended that the Commission consider a condition
of approval requiring that the “compacted gravel borrow” beneath the Reinforced Turf and the Stabilized Aggregate
Pathway contain 0% fines.
Findings
Based on these observations, TRC concludes that the application as revised is in general compliance with the
Stormwater Management Regulations.
Sincerely,
TRC Environmental
Jason M. Gold, P.E.
Manager, Civil/Site Engineering Services