LaBella Engineering letter.01.06.2023SP &s-ab1�
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LaBella
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January6, 2023
Mr. Craig Brown
Zoning Administrator and Code Compliance Officer
Town of Queensbury
742 Bay Road
Queensbury, New York 12804
Delivered via email only: CraigB@aueensburv.net
Re: Dunton Residence
Town of Queensbury, Warren County, New York
Labella Project # 2220706.54
Dear Mr. Brown:
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LaBella Associates has received a submission package from your office for the above referenced project.
The Applicant is proposing stormwater and runoff conveyance revisions to a recently constructed single-
family home. Information submitted to our office for review includes the following:
• Grading Plan, prepared by EDP LLP dated November 11, 2022, and;
• Stormwater Design Report, prepared by EDP LLP dated November 2022.
Your office has requested that we review the proposed revisions. Based upon our review, LaBella offers the
following comments for the Town's consideration:
Stormwater Management
1. The submission package pertains to a recently constructed project that was presented to the town as
site plan application SP65-2017. The submission package proposes stormwater and runoff conveyance
revisions generally in the subcatchments labeled Al and B1. Our review pertains to the stormwater
revisions that generally occur within Al and B1, and also include the receiving infiltration practice 1P. It
is noted that a cursory review indicates that SP65-2017 was considered a "minor" project per 147-11
of the Town code and total site disturbances were less than 1 acre so coverage under the Construction
General Permit was not required.
2. An as -built grading plan/site plan for Pond 1P is not provided. The applicant to revise the grading plan
to depict contours/spot grades for Pond 1P, the areas immediately surrounding Pond 1P, and the
primary spillway.
The Applicant shall provide an as -built detail for the Pond 1P including detailed as -built information for
the retaining feature (as depicted on site plans for SP65-2017 revised dated 02/22/2018) just west of
Pond 1P.
The detailed information for Pond 1P is required due to the proximity of Pond 1P to the northern adjoining
parcel and the fact that Pond 1P is designed not to completely exfiltrate; portions of the 10-year and 25-
year storm discharge across the overflow weir (Device #1 in HydroCAD). A comprehensive review of Pond
1P will be performed once sufficient information is provided to support a review of the HydroCAD model
inputs.
20 Elm Street 1 Suite 110 i Glens Falls. NY 128011 P (50 812-0513
www labeltapc.com
3. A review of letters pertaining to SP65-2017 indicate that additional test pits and infiltration tests were
to be performed at the commencement of construction. A cursory review of SP65-2017 do not indicate
that test pits and infiltration tests were performed in the bounds of 1P of the most recent plan set
submitted for that application. The Applicant to clarify if test pits and infiltration tests were performed
within the limits of Pond 1P.
A cursory review of correspondence for SP65-2017 indicates the project was considered a "minor"
project (although designed forthe "major" project standards). Town code 147-111(2)(a) states, "Location
of the infiltration devices shall be determined based on soil test results." Town code section 147-
111(2)(e) states, "the bottom of any infiltration device shall be a minimum of two feet above seasonal
high groundwater mark and two feet above bedrock." The Applicant to submit soil testing information
for Pond 1P in accordance with the town code.
4. Subcatchment 131 includes portions of the newly constructed site driveway. A cursory review of SP65-
2017 indicates that the stormwater controls proposed for the driveway may have been modified during
construction (SP65-2017 plans dated 03/16/18 depict a shallow depression area where this
submission shows infiltration trenches along the road). Further it appears that the alignment of the new
driveway was modified during construction.
Because the stormwater design and horizontal alignment appear to be modified it is unclear of the limits
of subcatchment B1 include all areas tributary to the new yard drain (including potential overflow
discharge from the infiltration trenches). The Applicant to clarify or revise accordingly.
Further, since the driveway alignment has been modified, are all tributary areas to Design Point B
analyzed in the post -development model?
5. It does not appear that the postdevelopment HydroCAD model nor post development map includes all
on -parcel (Dunton) tributary areas to Design Point B. See screenshot below (red highlight area). The
Applicant to revise accordingly.
6. The applicant to provide a detail and spot grades along the stone trench to understand the as -built
condition.
7. The Applicant to model the stone trench in HydroCAD.
8. There are inconsistencies pertaining to the size of the proposed pipe. The shallow yard drain and grading
plan propose a 6" PVC pipe, while the detailing grading and drainage plan detail proposes a 4" PVC pipe.
The Applicant to clarify and revise accordingly.
9. The Applicant to revise the HydroCAD model time span such that the full effects of the storm are realized
as the inflow depth indicates a ">" symbol.
10. The site plans shall be revised to include more spot grades at elevations 375.5 and 375.8 around the
yard drain to confirm the HydroCAD inputs.
11. The proposed elevations for the yard drain piping do not appear to match the HydroCAD model. For
instance, the yard drainpipe outlets to Pond 1P. The yard drainpipe outlet invert is 362.5, however the
basal elevation of Pond 1P appears to be modeled as 337.00. The Applicant to clarify or revise
accordingly.
Conclusion & Recommendation
It is our opinion that the applicant should provide clarification for the above items and incorporate changes
in subsequent plan submissions.
In the event the Planning Board or Town staff have any questions or require additional information, please
do not hesitate to contact me at (518) 824-1932.
Sincerely,
i
Richard Adams, PE
Senior Civil Engineer
cc: Shauna Baker, Town Planning Office Administrator (via email)
Laura Moore, Town Land Use Planner (via e-mail)
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