HomeMy WebLinkAboutSP-22-060 - Supplemental - 0224 0268 Market Street (61)The Stormwater Section has reviewed the “Market Street Lot B” site plan prepared by The Snyder
Group, Inc., dated 11/07/22. We would like to offer the following comments:
1. This project is located in the Potash Brook watershed. This watershed is listed as stormwater
impaired by the State of Vermont Department of Environmental Conservation (DEC). Please note
that Potash Brook is now classified as a warm water stream.
2. The project proposes to create greater than 1 acre of impervious area and disturb greater than 1
acre of land. It will therefore require a stormwater permit and construction permit from the
Vermont DEC Stormwater Division. The applicant should acquire these permits before starting
construction.
3. As the project proposes to create more than one-half acre or more of impervious surface, the
project is subject to the requirements of section 13.05 of the LDRs.
4. On the provided soil investigation logs, the VHB TP#4 lists SHWT at 3.5’ below grade, which is
approximately 310.5’. The mulch layer of the bioretention practice is at 313’, which would mean
that the bottom of the practice would be at 311’ as the VSMM requires a 24-48 inch deep
planting bed. The bioretention practice would have ≤0.5’ to SHWT, which is not incompliance
with the VSMM for an infiltration practice. The applicant should propose to line the practice.
5. Sheet D2 – Stormwater Details from VHB
a. The bioretention detail calls out a minimum of 24” from the mulch layer to SHWT. This is
inaccurate – SHWT should be two feet from the bottom of the bioretention soil media
since less than 1 acre of drainage area contributes to the system. The applicant should
revise the bioretention area detail to reflect requirements set by the VSMM.
b. The bioretention detail does not show a layer of bioretention soil media. The callout
says 18” of concrete sand. Per the VSMM, the bioretention planting bed should be 24 to
48 inches.
6. Sheet L-1.1 – Planting Plan
a. Several trees shown on the planting plan are too close in proximity to proposed
stormwater structures and pipes. The applicant should increase the separation between
proposed tree locations and stormwater infrastructure to prevent future damage.
b. There is a shrub proposed <1 ft away from a cleanout to the north of the lower trash
building. The applicant is advised to move this shrub location to prevent difficulty
maintaining the cleanout.
7. Sheet 5: EPSC Plan
a. What will be the phasing of construction regarding construction of buildings, site
grading, construction of stormwater treatment, etc.?
8. The applicant should provide a maintenance plan for the proposed stormwater infrastructure
per Section 13.05B(5). The DRB should include a condition requiring the applicant to regularly
maintain all stormwater treatment and conveyance infrastructure.
Thank you for the opportunity to comment.