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
January 12, 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: William Threw Lot 13 Site Plan Review
Town of Queensbury, Warren County, New York
Chazen Project # 91204.02
Queensbury Ref. No: Site Plan 2-2012
Dear Mr. Brown:
The Chazen Companies (Chazen) received a submission package from your office for a site p
for the above referenced project. Submitted information include
Plans entitled, William Threw, prepared by Hutchins Engineering, dated September 30, 2011;
A Stormwater Management Report, prepared by Hutchins Engineering;
A Site Plan Application with supporting documentation.
Your office has requested that we limit our review to the design
and sediment control items as it relates to compliance to local, state or relevant codes and r
Based on our review of the information provided, Chazen offers t
consideration:
Stormwater Management & Erosion and Sediment Control:
1.The proposed commercial development disturbs approximately 4.8 acres of land and therefore
requires the preparation of a Stormwater Pollution Prevention Plthat includes post-
construction stormwater management practices, in accordance with General Permit GP-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 50-year return interval storm for commercial projects. The
Applicant has provided stormwater analysis, but has not included the 50-year storm event. The
Applicant shall provide additional analysis in accordance with tThe Town of
Queensbury Requirement section of the SWPPP shall also be revised to reference the 50-yr storm
requirement.
Town of Queensbury
Site Plan 1-2012 William Threw Lot 13
January 12, 2012
Page 2
2.Section 6.3.1 of the NYSSMDM states that geotechnical testing must be performed within the
limits of each infiltration facility to determine the infiltrati
separate distance from seasonally high groundwater (minimum 3-feet). The applicant has
provided only a single test pit and percolation test in support
systems. However, no testing was provided in support of the infies, dry wells or
retention area designs. The applicant shall advance testing as required by the NYSSMDM to verify
the assumed infiltration rates of 10 and 30 inches per hour.
3.Section 147-11.I.2(c) of the Queensbury Town Code states that infiltration d
located down gradient of and separated from subsurface wastewater absorption fields by a
minimum of 20-feet.In addition, the NYS SWDM states that infiltration trenches
25-feet downgradient from septic systems. The northern proposed absorption system is located
less than 10 feet from a proposed infiltration trench. The Applicant shall revise as required to
demonstrate compliance with the referenced regulations.
4.Section 6.3.3 of the NYSSWDM states that a minimum pretreatment
shall be provided prior to entry into an infiltration facility. If the infiltration rate is greater than 5
in/hr, as assumed, then 100% of the WQv shall be pretreated prior to entry into the infiltration
facilities. The Applicant shall ensure that pretreatment requirements are be
supporting calculations for all infiltration devices.
5.Section 6.3.6 of the NYSSWDM states that infiltration practices shall never serve as a sediment
control device during construction. The Erosion & Sediment Control plan indicates that the
shallow retention areas will be used as temporary sediment basin
depicts silt fence around the perimeter of the bottom infiltration trenches. Due to the nature of
the basin and the likelihood of ponding water, it is unlikely th
protect the infiltration trench from sediment. The applicant shall consider using a rock berm or
similar measure, in addition to the silt fence. In addition, the Applicant indicates an exfiltration
rate of 2in/hr within the retention basins themselves. As such,
used as temporary sediment basins.
6.The Applicant shall provide a general detail for the proposed infiltration trenches, to incl
appropriate material specifications. Please note, the NYSSWDM re
infiltration trench be lined with an acceptable filter fabric, ifine gravel
or sand layer above the course gravel treatment reservoir.
7.Section 6.3.6 of the NYSSWDM requires that an observation well b
trench and dry well. The Applicant shall revise the plans & deta
8.The proposed impervious cover statistics for parcel 13 in the St
not consistent with the values listed on the Layout and Utility
The Applicant shall revise for consistency.
9.It is noted that the proposed dry wells appear to be receiving runoff from impe
are not limited to only roof runoff. According to New York State
Manual (NYSSMDM) Section 6.3.1, the drainage area to dry wells sof runoff only.
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Town of Queensbury
Site Plan 1-2012 William Threw Lot 13
January 12, 2012
Page 3
As such the applicant shall revise the design to demonstrate compliance with the refer
standard.
10.The Area Listing in the existing conditions HydroCAD model indic
impervious surface. However, the existing total non-permeable areas listed in the site plan
applications for Lots 12 & 13 indicate a total of 3.29 Acres. In
increases in impervious area are 1.536 and 0.211 Acres for Lots
would indicate an increase of 1.747 Acres of impervious surface, while the models
increase of 2.278 Acres. The Applicant shall revise these values
11.The overall watershed boundary should not be limited to the subj, but shall
include the entire watershed tributary to each Subcatchment/Design P
applicant should revise the boundaries appropriately. USGS topog
used for offsite areas.
12.The intent of stormwater quantity control is to prevent an incre
discharge point from the site, or design point. In comparing the
Link 2L actually has increased runoff volumes at the 10-, 25-, and 100-year storm events under
proposed conditions. The increased runoff must be mitigated at
value is less than or equal to the existing rate.
13.Per Section 4.4 of the NYSSWDM, the length of overland flow used
calculations is limited to no more than 100ft for post developme
HydroCAD model presents sheet flow lengths of 175 or 125ft for sts 1S, 2S, 3S, 5S, and
7S. The Applicant shall revise the time of concentrations approp
allowed time of concentration, per NYSDEC regulations, is 6-minutes. The applicant shall revise
the calculations to use a minimum time of concentration of 6-minutes where appropriate (i.e. in
subcatchments were the time of concentration is less than 6 minu
calculations in the SWPPP.
14.The proposed HydroCAD model indicates a bottom of stone elevatio infiltration
trench 9P. However, the Grading & Drainage plan indicates an ele
shall revise for consistency.
15.The proposed HydroCAD model indicates a bottom of stone elevatio
trench within retention basin 13P. However, the Grading & Drainage plan indicates an e
374.5. The Applicant shall revise for consistency.
16.The Applicant indicates a total disturbance of 4.8 Acres betweenPlease note, per
Part II.C.3 of the 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 prio
Department or the MS4. It is recommended that notes are added to the drawings indicating to the
Contractor that the five acre limit cannot be exceeded.
17.The Applicant shall provide clarification regarding the intendedof the proposed
equipment storage yard, in addition to whether or not this area has been i
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Town of Queensbury
Site Plan 1-2012 William Threw Lot 13
January 12, 2012
Page 4
project disturbance. Also, it is requested that that Applicant provide clarification
gravel or stone will be placed to create a laydown area within t
18.The Applicant states that an inquiry has been made to the NYSDEC regarding an endangered
species impact determination. Once a determination has been made
the Town with supporting documentation and revise the SWPPP to i summary of such
documents, to ensure compliance with Part I.D.4 of the General Permit.
19.The Applicant states that there are no nationally registered his
project and has included a screening map from the OPRHP website. Based upon this map, it is
evident that the entire site falls within a designated Archeologically Sensitive Area, which is
defined by OPRHP as areas within the state where the discovery of archeological sit
predicted. Per Part III (A) (8) b of the General Permit, areas of archeolog
indicate the need for a survey. As such, the Applicant shall coordinate with the Offi
Recreation, and Historic Preservation (OPRHP) to determine the n
potential for impact to historic or archeological resources. Adduired to
ensure compliance with this section of the General Permit.
20.A stabilized construction entrance shall be indicated on the Ero
a detail shall be added in accordance with the NYS Specificationt
Control.
Conclusions and Recommendations
It is our opinion that the applicant should provide clarificatio
changes in subsequent plan submissions.
If you have any questions regarding the above, please do not hesitate to me at (518) 824-1926.
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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