TDE Response Letter900 Route 146 Clifton Park, NY 12065
(P) 518.371.7621 edpllp.com
Date: June 13, 2022
To: Mr. Craig Brown
Zoning Administrator and Code Compliance Officer
Town of Queensbury
742 Bay Road
Queensbury, NY 12804
Re: Carlson Residence
Queensbury Ref #SP 26-2022
Dear Mr. Brown:
The Environmental Design Partnership, LLP (EDP) is providing you this letter in response to review
comments provided by the LaBella dated May 23, 2022. On behalf of the applicant Eric Carlson, we offer
the following response to comments and additional information:
1. According to the site plan limit of disturbance and proposed limit of disturbance on the site plan
application, this project proposes to disturb +/- 34,000 SF. Projects that disturb greater than 15,000 SF
are considered Major Projects per Town code section 147-11.E.(2). In accordance with Town code
section 147-11.I.(3)(c), Major Project stormwater control measures shall be designed so that there will
be no increase in runoff volume from a ten-year-frequency/twenty-four-hour-duration storm event
following development over the predevelopment volume, and for storm events exceeding the ten-year
design storm, the stormwater controls measures shall function to attenuate peak runoff flow rates for a
twenty-five-year frequency storm to be equal to or less than predevelopment flow rates. The Applicant
has provided a stormwater analysis for review.
Response: Comment noted.
2. According to the site plan limit of disturbance and proposed limit of disturbance on the site plan
application, this project proposes to disturb +/- 34,000 SF. Projects that disturb greater than 15,000 SF
are considered Major Projects per Town code section 147-11.E.(2). In accordance with Town code
section 147-11.I.(3)(c), Major Project stormwater control measures shall be designed so that there will
be no increase in runoff volume from a ten-year-frequency/twenty-four-hour-duration storm event
following development over the predevelopment volume, and for storm events exceeding the ten-year
design storm, the stormwater controls measures shall function to attenuate peak runoff flow rates for a
twenty-five-year frequency storm to be equal to or less than predevelopment flow rates. The Applicant
has provided a stormwater analysis for review.
Response: Comment noted.
3. The subcatchment boundaries extents appear to be the extent of the parcel, however the
subcatchment boundaries shall include all tributary areas (on site or offsite). The Applicant shall revise
the boundaries accordingly as applicable, and the Applicant can use USGS information for offsite
areas.
Response: Comment noted, subcatchment boundary has been updated to include a small
portion of offsite tributary area. HydroCAD model has been updated to reflect additional area.
4. The HydroCAD model and the subcatchment map do not appear to be consistent. For example,
Subcatchment 1 (S1), is shown as being 4,300 square feet in the site plans but is labeled as 2,820 in
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900 Route 146 Clifton Park, NY 12065
(P) 518.371.7621 edpllp.com
Mr. Craig Brown
June 13, 2022
Page 2
the HydroCAD model. Similar inconsistencies appear in other subcatchments. The Applicant to revise
accordingly.
Response: Comment noted, HydroCAD model has been updated to match subcatchment
mapping.
5. The broad crested overflow weir associated with Pond SMA#2 appears to have inconsistent overflow
weirs. The overflow weir invert is shown as being 335.50 in the HydroCAD model but is modeled at
elevation 335.90 in the site plans, Applicant is to revise for consistency.
Response: The plans and HydroCAD have been updated to abandon SMA#2, with additional
flows entering into SMA#1.
6. It does not appear that the culvert connecting SMA #1 to SMA #2 is included in the HydroCAD model.
The Applicant to revise accordingly.
Response: Comment noted, plans and HydroCAD have been updated to abandon SMA#2 and
corresponding culvert.
7. The SMA #6, 7, and 3 site plan inverts and elevations do not appear to match the HydroCAD model
and shall be revised accordingly.
Response: Comment noted, plans and HydroCAD have been updated for consistent inverts
and elevations throughout.
8. The SMA #5 peak elevations exceed the capacity of the system. For instance, the 25-year storm peak
elevation is 406.10 but the top of the practice is 337.25. The Applicant to revise accordingly.
Response: The HydroCAD model has been updated for peak elevation and top of practice to be
equal.
9. The applicant currently shows two test pit #4’s on the existing conditions plan. Applicant shall clarify
which test pit location is correct.
Response: The existing conditions sheet has been updated to depict correct test pit location.
10. The NYS SMDM states that “Infiltration practices cannot be located on areas with natural slopes
greater than 15%” and “Infiltration practices cannot be located in fill soils”. It appears the site has
slopes throughout the site that exceed 15%, including in the locations of the infiltration practices (SMA
6). Additionally, the infiltration practices appear to be located in fill soils. Previous correspondence
received from the NYS DEC regarding projects with similar concerns of locating stormwater features
in fill slopes has resulted in the following recommendations:
“At a minimum, the designer must meet the following guidance and provide
justification/demonstration of equivalence in the SWPPP:
· Insitu/natural soil layer below the infiltration system has an infiltration rate greater than or equal to
the 0.5 in/hr
· Ground water and bedrock levels in insitu/natural soil should be at least 2 – 3 feet below grade
· Fill material is an engineered fill that is tested after placement (by geotechnical firm) and
demonstrated to be equivalent to a soil material acceptable for the installation of an infiltration (i.e.
infiltration rate greater than or equal to .5 in/hr, etc.). Infiltration rate of fill material should be similar
infiltration rate as insitu/existing soil.
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900 Route 146 Clifton Park, NY 12065
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Mr. Craig Brown
June 13, 2022
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· If there is a difference in the infiltration rates between the fill and insitu/native soil, the designer
should use the more conservative (i.e. slower infiltration rate) when determining whether the
infiltration system will dewater (exfiltrate) with the required 48 hours (see Section 6.3.2 “Conveyance’
of the Design Manual)
· Required vertical separation distances to groundwater/bedrock are maintained
· Required horizontal separation distances to surface waters, wells, etc. are maintained
· There is adequate fill along the edges of the infiltration system to prevent seeps/breakouts”
DEC has indicated that with regards to the 15% limit, they have allowed designers to use the cut/fill
approach provided the criteria above is met. As such, the Applicant should demonstrate compliance
with the provisions outlined by the DEC
Response: Infiltration testing has been performed in stormwater management devices and soil
infiltration rates are greater than 0.5 inches/hour. Within stormwater management areas,
groundwater and bedrock separation distances will meet requirements. Fill material to be
similar to insitu/natural material and be tested after placement.
11. Town Code Section § 147-11I(3)(c)[4] states that “Infiltration devices for major projects shall be located
a minimum of 100 feet from Lake George and any down-gradient drinking water supply, lake, river,
protected stream, water well, pond, wetland; a separation of more than 100 feet may be required in
cases where contamination of the water supply is possible due to highly permeable soils, shallow
groundwater and similar situations. The separation distance shall be a minimum of 50 feet from
upgradient water supplies. Designs shall mitigate adverse effects that groundwater recharge will have
on adjacent wells, water supplies, wastewater treatment systems, buildings, roadways, properties, and
stormwater control measures. Stormwater recharge areas shall be located a minimum of 100 feet from
the subsurface treatment system of a wastewater treatment system unless it is demonstrated that a
lesser separation will not adversely affect the functioning of such leach fields.”
It appears that infiltration practices SMA 7 and SMA 6 are within 100 feet of Lake George. The design
shall be revised or seek a waiver from the subject town code section.
It appears that infiltration practices SMA 1 through 5 are within 100 feet from the subsurface treatment
system. The Applicant to revise accordingly or demonstrate that a lesser separation will not adversely
affect the functioning of such leach fields.
Response: An area variance is being requested from the town. Wastewater location is at a high
point with stormwater management areas located down slope. Therefore, there will not be any
impact on the existing wastewater system.
12. Section 147-11I(3)(d)[3] of the town code requires pre-treatment practices prior to infiltration practices.
It is unclear what pre-treatment practices are proposed for the infiltration practices. The Applicant to
revise or clarify accordingly.
Response: Pre-treatment for shallow grass depressions consists of a three (3) foot, minimum,
wide grass filter strip.
13. The applicant is to show neighboring water wells on adjacent properties and or clarify the potable water
sources for adjacent properties.
Response: Comment noted, all adjacent properties obtain water supply from the lake.
14. It appears multiple retaining walls are proposed on the site plans. The NYS Standards and
Specifications for Erosion and Sediment Control (SSESC) states, “The design of any retaining wall
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900 Route 146 Clifton Park, NY 12065
(P) 518.371.7621 edpllp.com
Mr. Craig Brown
June 13, 2022
Page 4
structure must address the aspects of foundation bearing capacity, sliding, overturning, drainage and
loading systems. These are complex systems that should be designed by a licensed professional
engineer.” The Applicant to provide the design for the wall prior to construction so long as the Town
does not take exception to this approach. The design shall be developed in accordance with the NYS
SSESC and other regulating documents (for example, the residential building code).
Response: Comment noted, retaining wall designs will be provided prior to construction.
15. A legally binding and enforceable maintenance agreement may be required to be executed between
the landowner and the Town ensuring that proper maintenance measures will be implemented for all
proposed stormwater management practices in accordance with Section 147-10.D of the Town Code.
Response: A draft maintenance agreement has been included in the storm report.
If you have questions or require additional information, please contact our office at your convenience.
Very truly yours,
The Environmental Design Partnership, LLP
Connor DeMyer
Project Engineer