Engineering comments
North Country Office
100 Glen Street, Glens Falls, NY 12801
P: (518) 812-0513 F: (518) 824-8391
www.chazencompanies.com
Hudson Valley Office (845) 454-3980
Engineers
Environmental Professionals Capital District Office (518) 273-0055
Land Surveyors
Landscape Architects
Planners
February 16, 2012
Mr. Craig Brown
Zoning Administrator and Code Compliance Officer
Town of Queensbury
742 Bay Road
Queensbury New York 12804
Delivered via email only: CraigB@queensbury.net
Re: Baybrook Professional Park Lot 3-7 Site Plan Review
Town of Queensbury, Warren County, New York
Chazen Project # 91204.06
Queensbury Ref. No: Site Plan 14-2012
Dear Mr. Brown:
The Chazen Companies (Chazen) received a submission package from your of
for the above referenced project. Submitted information include
Plans entitled, Baybrook Professional Park Lot 3-7, prepared by Nace Engineering, P.C., and
Miller Associates, dated January 15, 2012;
A Stormwater Management Report and Stormwater Pollution Preventi
by Nace Engineering , P.C.; and
A Site Plan Application with supporting documentation.
Your office has requested that we limit our review to the design of stormwater
and sediment control items as it relates to compliance to local,
Based on our review of the information provided, Chazen offers the following comments for the Towns
consideration:
Stormwater Management & Erosion and Sediment Control:
1.The proposed residential development disturbs approximately 4.34 acres of land and therefore
requires the preparation of a Stormwater Pollution Prevention Plan (SWPPP) that includes post-
construction stormwater management practices, in accordance with-0-10-001.
Additionally, Section 179-6-080 of the Town Code states that stormwater drainage plans shall
analyze the impacts of a project using a 25-year return interval storm for residential projects. The
Applicant has provided stormwater analysis, but has not included-year storm event. The
Applicant shall provide additional analysis in accordance with t
Town of Queensbury
Site Plan 14-2012 Schermerhorn Commercial Holdings
February 16, 2012
Page 2
2.Part I.D.4 of the General Permit, prohibits discharges from construction
affect a listed or proposed to be listed, endangered or threaten
Documentation that this project complies with this provision of the General Permit needs to be
provided in order to support permit eligibility. This informatioincluded within the
SWPPP with reference made to any supporting studies completed.
3.Part III.A.8. of the General Permit requires that the SWPPP contain documentation regarding Part
I(D)(8) - Historical Places or Archeological Resource, in support of the determination of permit
eligibility. At a minimum the criteria outlined in Part III(A)(
support permit eligibility. This shall be included within the SWPPP with reference made to any
supporting studies completed.
4.The contractor certification provided in the SWPPP shall be revi
III.A.6 of the General Permit. In addition, the certification page shall also identify the specific
elements of the SWPPP that each contractor and subcontractor wil
information stated in part III.A.6 of GP-0-10-001.
5.Part III.B.1.J requires that the SWPPP include a description of ution prevention measures
that will be used to control litter, construction chemicals, and
a pollutant source in the stormwater discharges. Please revise the SWPPP to include this
information.
6.The Applicant indicates a total disturbance of 4.34 Acres. Please note, per Part II.C.3 of th
General Permit, the owner or operator of a construction activity shall not disturb greater than five
(5) acres of soil at any one time without prior written authoriz or the
MS4. It is recommended that notes be added to the drawings indicating to the Contractor that the
five acre limit cannot be exceeded.
7.The overall watershed boundary shall not be limited to the subje
the entire watershed tributary to each Subcatchment/Design Point. Pursuant to t
should revise the boundaries appropriately. USGS topographical i
offsite areas. Additionally, the design point(s), and time of caths shall be
indicated on the subcatchment map. A pre-development subcatchment map has not been
provided as indicated in the list of appendices.
8.Based upon the existing and proposed grading provided, it appears that there are multiple
discharge points (design points) for the property. However, the HydroCAD model only
single design point and a single existing subcatchment that discs to Old Maids Brook. A more
detailed Existing Conditions model, as well, appears to be warranted to provide an accurate
comparison. Particularly, the addition of the berm at the northe
change the watershed boundary from pre- to post-development conditions. Such changes shall be
accurately depicted.
9.The Applicant accounts for an exfiltration rate of 0.25 in/hr in the HydroCAD model for the
proposed eave trenches. In addition, the SWPPP indicates that th
and slowly infiltrate the runoff from most storms. As such, thting as
infiltration practices and shall conform to the requirements of Section 6.3 of
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February 16, 2012
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Applicant shall perform required soil testing to ensure that the
trenches are adequately separated from bedrock and seasonally high groundwater, as well as
verify the rate of infiltration. Please note that a minimum infiltration rate of 0.5 in/hr is req
for a practice to be suitable for infiltration.
Further, 6.3.1 of the NYSSWDM states that infiltration trenches shall be setback from structures
by a minimum of 25-feet. As such, the applicant should revise the design to comply with this
provision of the manual. It is noted that the applicant could co
leaders to convey roof runoff to infiltration trenches.
10.The Applicant has stated that excavations were performed as part of the subdivision approval. The
Applicant shall include the location and results of these tests on the current grading and drainage
plan for reference.
11.The SWPPP indicates that through the use of infiltration (eave) trenches, bioretention, and small
infiltration basins, over twice the WQv is being infiltrated or
Stormwater Green Infrastructure requirements. However, the appli
runoff reduction volume (RRv) calculations to substantiate this statement. These calculations shall
conform to Section 3.6 and 4.3 of the NYS SMDM, to demonstrate that 100% of the WQv is
reduced by applying a combination of green infrastructure and sts with RRv capacity.
Refer to Table 3.5 in the NYSSMDM for the RRv capacity provided
proposed for runoff reduction. Should less than 100% of the WQv
provide justification in the SWPPP that evaluates each of the green infrastructure techniques
listed in Table 3.2 and identify the site limitations that make
12.The SWPPP states that the required water quality volume (WQv) is-feet, and the
provided WQv is 0.251 acre-feet; however, the applicant has not provided any supporting
calculations. A calculation for the required WQv shall be inclu
treatment provided by each proposed stormwater management practi
with supporting calculations for each practice.
13.According to Section 6.4.4 of the NYSSMDM the entire bioretentio
pretreatment) shall be sized to temporarily hold at least 75% of
Supporting calculations shall be provided indicating the WQv treatment being provided by the
bioretention facility.
14.The Applicant shall provide an installation detail and/or cross section for the proposed detention
pond, clearly indicating which stormwater practice (P-1, P-2, P-3, P-4, or P-5) from the NYS SMDM
is being proposed, or if it is a deviation from the technical standards. The detail shall include
appropriate material specifications, pretreatment and treatment
any required landscaping. The applicant shall also include applicable design calculations for
stormwater basin in accordance with the NYS SMDM. The SWPPP shall be revised to include a
detailed description of this practice.
15.Question 27 of the NOI indicates that the proposed shallow swale will act as a Type O-1 Dry Swale.
If this is indeed the intent, the Applicant shall provide a detailed description in the SWPPP, as well
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February 16, 2012
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as an installation detail indicating appropriate material specifications and geomet, in
conformance with Section 6.5 of the NYS SMDM.
16.It is recommended that the applicant install construction fence
to the wetland area on site, to ensure that the existing wetland
construction.
17.The catch basin detail presented on Sheet SP-6 indicates that compacted gravel will be used as a
base for catch basin placement. It is recommended that the depth of the gravel material be
indicated on the detail.
18.The Erosion and Sediment Control Plan indicates that the use of two (2) sediment traps. However,
the Implementation Schedule and the NOI indicate the use of sediment basins. The Applicant shall
revise for consistency.
19.The Applicant shall add a note or detail indicating the topsoil, seed, and mulch specifications, as
well as appropriate application rates for both temporary and permanent site stabilization.
20.A note s hall be added to the erosion and sediment control plan stating tErosion and
Sediment controls depicted hereon are intended to provide a geneding of Additional
erosion and sediment control measures not depicted hereon may be
and will be employed as necessary to prevent erosion and sedimen
the site .
21.The applicant shall include Construction Specifications as presented in the NYS Standard
Specifications for Erosion and Sediment Control, to the Silt Fence, Stone Lined Swale, and Inlet
Protection Details presented on Sheets SP-3 and SP-7.
22.The NOI indicate the use of sediment traps and stone check dams, during construction. As such,
material specifications and installation details shall be provid
NYS Standards and Specifications for Erosion and Sediment Control. In addition, the Erosion and
Sediment Control Plan shall clearly indicate where each of these practices shall b
23.In accordance with the NYSSMDM, a note shall be added to the pla dense and
vigorous vegetative cover shall be established over the contributing pervious drainage areas
before runoff can be accepted into the infiltration and bioreten
24.A legally binding and enforceable maintenance agreement shall be e
owner and the Town ensuring proper maintenance measures for all proposed stormwater
management practices are being followed. The maintenance requirements indicated in the
NYSSMDM for each practice shall be specified in the SWPPP as par
Maintenance Manual. A draft of this agreement shall be provided to the Town for revi
included in the SWPPP.
A maintenance easement shall also be executed and recorded in the office of the County Clerk,
that shall be binding on all subsequent land owners served by thtormwater management
facility. The easement shall provide access to the facilities at reasonabl
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February 16, 2012
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inspection by the Town of Queensbury to ensure that they are mai
condition.
Conclusions and Recommendations
It is our opinion that the applicant should provide clarification for t
changes in subsequent plan submissions.
If you have any questions regarding the above, please do not hes-1926.
Sincerely,
Sean M. Doty, P.E., LEED AP
Senior Project Engineer
cc: Pam Whiting, Town Planning Office Administrator (via email)
Keith Oborne, Town Planner (via email)
Joel Bianchi, P.E., Senior Director - Municipal Engineering (via email)
File
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