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Chazen Engineering Comments THE Gba �� North Country Office — 375 Bay Road, Queensbury, NY 12804 P: (518) 812-0513 F: (518) 812-2205 COMPAN I E5 www.chazencompanies.com Proud to be Employee Owned Hudson Valley Office (845)454-3980 Engineers Land Surveyors Capital District Office (518) 273-0055 Planners Environmental Professionals Landscape Architects October 13, 2016 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: Michael& Elaine Feeney Town of Queensbury, Warren County, New York Chazen Project#91600.46 Queensbury Ref#PZ 231-2016 Dear Mr. Brown: The Chazen Companies (Chazen) has received a submission package from your office for the above referenced project. The applicant intends to construct a single family home with attached garage and driveway. Submitted information includes the following: • Site Plans titled "Michael Feeney", by EDP, LLP, dated September 8, 2016; • Stormwater Control Report, by EDP, LLP, dated September 2016; • SWPPP, by EDP, LLP, dated August 2016; • Town of Queensbury Site Plan Application; • Project narrative, by EDP, LLP, dated September 15, 2016, and; • Town of Queensbury Freshwater Wetlands Permit Applications. Your office has requested that we limit our review to the design of stormwater system as it relates to compliance to local, state or relevant codes and regulations. Based upon our review, Chazen offers the following comments for the Town's consideration: Stormwater Management& Erosion and Sediment Control: 1. The project proposes to disturb over 1 acre of land and requires the preparation of a Stormwater Pollution Prevention Plan (SWPPP) in accordance with GP-0-15-002 that includes erosion and sediment controls. A Stormwater Pollution Prevention Plan (SWPPP) has been provided. Comments relating to the Stormwater Management Report and SWPPP are offered below. It is noted that construction of single family homes (between 1 and 5 acres of disturbance) not located in one of the watersheds listed in Appendix C of the General Permit or Chazen Engineering, Land Surveying&Landscape Architecture Co.,D.P.C. Chazen Environmental Services, Inc. The Chazen Companies, Inc. Town of Queensbury Michael&Elaine Feeney October 13,2016 Page 2 not directly discharging to one of the 303(d) segments listed in Appendix E of the General Permit are not required to include post-construction stormwater management practices. 2. This project falls within the Lake George watershed and will be subject to the requirements of Section 147-11 of the Town code, for Projects within the Lake George Park. The project proposes to disturb over 15,000 square feet and is considered a "major" project. 3. Section 179-6-080 of the Town Code, states that stormwater drainage plans shall analyze the impacts of a project using at least a 25-year return interval storm with regards to both runoff rate and volume for residential projects. 4. The Applicant shall depict the time of concentration flow paths for the existing and proposed subcatchments on the drainage maps. Also, it appears additional tributary area to the site may exist, past the western property boundary. As such, the Applicant should provide additional information regarding the watershed boundary selected or expand the watershed to any further western extents. 5. The HydroCAD model does not provide distinct inflow depths as evidenced by the ">", which indicates a time span of 5-20 hours may not be sufficient. The Applicant to revise the HydroCAD time span so the full effects of the storm are realized. 6. The Applicant shall ensure the specific erosion control measures prescribed Section 147-11-J are included in the erosion control notes (i.e. 147-11-J(3)(b) and (c)). 7. It appears that swales #2 and 3 are within 100 feet of the onsite wetland. Section 147-11- I(3)(c)[4] states, "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;..." The Applicant shall revise the design to conform to 147-11- I(3)(c)[4] or request a variance for the same. 8. Page 5 of the Applicant's SWPPP, regarding endangered or threatened species as required by Part I.F.4 of the SPDES GP-0-15-002, indicates a letter has been directed to NYSDEC New York Natural Heritage Program requesting they provide a determination. The Applicant shall provide the town with any documentation regarding the above determinations and incorporate the same into the SWPPP pursuant to section Part I.F.4 of the SPDES General Permit. 9. The Applicant shall depict a stabilized construction entrance on the erosion and sediment control plan and provide a detail in accordance with the New York State Standards and Specifications for Erosion. 10. The eave trench is modeled at a depth of 3 feet but the detail on sheet 2 depicts a depth of 2 feet; the Applicant to revise accordingly. 11. The Applicant should consider modelling the roadside drainage channels and provide a detail of the roadside drainage channels. Are temporary check dams needed? Does the swale need to be lined? Should permanent check dams be employed? Z:\projects\91600-91699\91600.00-Town of Queensbury\91600.46-PZ231-2016-Michael&Elaine Feeney\ENG\91600.46-MichaelElaineFeeney_2016-10-13_L1.docx Town of Queensbury Michael&Elaine Feeney October 13,2016 Page 3 12. The site plans depicts retaining walls along the driveway(7 feet max and 6 feet max) as designed by others. Page 4.48 Retaining Walls of the New York Standards and Specifications for Erosion and Sediment Control (July 2016 edition) states, "The design of any retaining wall 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 shall ensure the retaining walls are designed in conformance with the NYSSESC. The retaining wall designs shall be submitted to the town for review once completed. 13. The existing and proposed culvert design in the HydroCAD model does not take into account inlet/outlet conditions as well as entrance losses on the inlet structure. This will most likely require the Applicant to model the ponding conditions upstream and downstream of the culvert. The Applicant shall revise the culvert conditions in the HydroCAD model to reflect the actual conditions. Also, according to the pipe trench detail, the invert of the proposed culvert is filled by 7"; this shall be reflected in the culvert design in the HydroCAD model. Also, what is the basis of design for the culvert? Is it intended to convey a 100-year storm event? 14. Once the HydroCAD model has been revised based on the above comments, conformance to the following "major" project design requirements will be performed: Section 147-11-I(3)(c)[1] states, "Stormwater control measures shall be designed so that there will be no increase in runoff volume form a ten-year frequency/twenty four-hour-duration storm event following development over the predevelopment volume.". Section 147-11-I(3)(c)[2] states, "For storm events exceeding the ten-year design storm, the stormwater control 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." 15. Section 147-11-I(3)(c)[3] states, "Infiltration devices shall be designed such that the bottom of the system will be a minimum of two feet above the seasonal high groundwater level to be realized following development." It does not appear that test pits were performed at the proposed location of the infiltration devices. The Applicant to perform test pits and update the SWPPP and plans with the results to ensure conformance with 147-11-I(3)(c)[3]. 16. Section 147-11-I(3)(c)[6] states, "Infiltration devices shall be designed based on the infiltration capacity of the soils present at the project site." The Applicant shall perform falling head permeability tests in accordance with Appendix D of the stormwater design manual to confirm the exfiltration rates used in the HydroCAD model. 17. Table 1 of Appendix 5B of the DOH Standards for water wells indicates a minimum separation distance of 50 feet from "Surface water recharge absorption system with no automotive-related Wastes." Portions of the eave trench appear to be within 50 feet of the proposed water well. The Applicant shall revise the design to conform to the DOH standards. Z:\projects\91600-91699\91600.00-Town of Queensbury\91600.46-PZ231-2016-Michael&Elaine Feeney\ENG\91600.46-MichaelElaineFeeney_2016-10-13_L1.docx Town of Queensbury Michael&Elaine Feeney October 13,2016 Page 4 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) 824-1926. Sincerely, �� 141 7p�5- ' Sean M. Doty, P.E., LEED AP, CMS4S Principal Manager, Municipal Engineering Services cc: Sunny Sweet,Town Planning Office Administrator(via email) Laura Moore,Town Land Use Planner(via e-mail) File Z:\projects\91600-91699\91600.00-Town of Queensbury\91600.46-PZ231-2016-Michael&Elaine Feeney\ENG\91600.46-MichaelElaineFeeney_2016-10-13_L1.docx