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HomeMy WebLinkAbout20190098 Saratoga Honda Expansion Correspondance V ARCHITECTURE ENGINEERING }+ I_ PLANNING CPLteam.com u N May 2, 2019 co Susan Barden — 0 City of Saratoga Springs City Hall—474 Broadway Saratoga s a S rin NY 12 8 6 6 Z g Springs, z E 03 RE: City of Saratoga Springs —Site Plan Review—PB App. No. 2019009803 Saratoga Honda Expansion 0 Dear Susan: We are in receipt of revised documents and responses to our initial comments on the above ; referenced project. The following documents have been submitted by The LA Group Landscape Architecture & Engineering, P.C. in response to our March 28, 2019 comments: Comment Response Letter, Revised SWPPP and Revised Drawings dated April 3, 2019. Our initial comments are provided below for your reference, followed by LA Group response in italics and current stats of comment resolution in bold type. M SWPPP Review SWPPP Report 1. Page 1, Section 2.2 — Changes to the SWPPP must be approved by the City prior to any construction. LA Group Response: Comment noted CPL Response: Please revise to "the City of Saratoga Springs must approve any planned amendments or modifications" 2. Page 2, Section 3.5, 2nd paragraph — Please review wording. Our recommendation is that an updated letter be obtained from OPRHP as the last letter was dated 4/9/2014 — approximately 5 years ago and regulations, etc. may have changed. LA Group Response: Proposed project is in an area that was generally disturbed during the last phase of the project. Letter received from OPRHP does not have an expiration date and per discussions with the previous Archaeological Consultant for the project they do not see a need to update the letter received from OPRHP. CPL Response: Comment Addressed pending City approval. 3. Page 7, Section 5.4—The Peak flows indicated in the Table do not match the calculations. LA Group Response: Table has been revised to match Hydro CAD calculations. CPL Response: Comment addressed. 4. Page 10, Section 8 -Section references "items" but there are only "bullets". LA Group Response: Bullets were switched to numbers. PB No. 20190098 May 2, 2019 Page 2 of 5 CPL Response: Comment addressed. 5. Please show concrete washout locations, staging areas, etc. LA Group Response: Concrete washout and staging area locations have been added to Sheet L-1.0. CPL Response: Comment addressed. 6. The area under existing and proposed conditions should be the same. LA Group Response:Proposed watershed is 3.77 acres. Discrepancy between existing and proposed conditions is 42 square feet. This area represents 0.02% of the total drainage area. This discrepancy is insignificant. CPL Response: Comment addressed. 7. Subarea 1.1s —Please explain how the Time of Concentration is the same under existing and proposed conditions when the path has changed? Please verify the CN number for existing and proposed conditions. LA Group Response:Proposed condition Time of Concentration(Tc)for subcatchment 1.1s has been updated. The Tc has reduced by 2.4 minutes from pre to post-development. CPL Response: Comment addressed. 8. Subarea 1.1s—Please explain how the time of concentration path was chosen. LA Group Response: The longest time of concentration path was chosen. Note that the proposed condition Tc path has been revised. CPL Response: Comment addressed. 9. Please explain why the size of the infiltration area has been reduced in area? LA Group Response: The original infiltration area was oversized for potential future development. Proposed infiltration basin is sized to hold the 100 year storm event, as required by NYSDEC. CPL Response: Comment addressed. 10. Please provide infiltration tests results. Please insure that the tests have been completed in conformance with the guidelines noted in the NYS Stormwater Management Design Manual. LA Group Response:Falling head permeability test results have been added to Appendix B of the SWPPP. CPL Response: The test provided are from 2012. Comment addressed pending City approval. 11. As noted in the NYS Stormwater Management Design Manual, infiltration must be separated by at least 3 feet vertically from seasonal high-water table. Please verify. LA Group Response: Test Pit 1 was conducted at an elevation of 306.0'and noted seasonal high groundwater at 3' deep, or elevation 303.0'. The lowest proposed elevation of the porous pavement is 307.34. Proposed porous pavement section is 16" deep which would provide a bottom of stone elevation of 306.0 and provide 3'of separation. In existing conditions stormwater is treated by the Pocket Pond. Treated stormwater in the Pocket Pond overflows to the existing infiltration pond(stormwater disposal area). The PB No. 20190098 May 2, 2019 Page 3 of 5 infiltration pond does not need to be separated by 3 vertical feet from seasonal high-water as it is not providing treatment of runoff, and only disposal. LAG received approval of this from DEC and City of Saratoga Springs. The bottom of the infiltration pond is above the seasonal high-water table. CPL Response: Please provide correspondence, etc. from NYSDEC and City of Saratoga Springs. 12. Post Development Subarea 3.3s — Why is the Time of Concentration for Proposed Conditions less than the Tc for Existing Conditions? LA Group Response: Proposed condition models the newly constructed swale as a Reach, therefore the proposed conditions Tc path length was reduced and included in the Reach. CPL Response: Comment Addressed. 13. Is the pocket pond suppose to hold water permanently up to an elevation of 305'? If so, is the pond lined? LA Group Response: Pocket pond was modeled as worst-case scenario with a permanent pool elevation. Current pond does not have a clay liner and is only lined with topsoil. Relocated pond will match existing conditions. CPL Response: Comment Addressed. 14. For storms larger than the 100-year storm, how will stormwater runoff overflow the infiltration basin? Should an emergency overflow be installed? LA Group Response: The NYSDEC Manual does not require modeling or design for storms greater than the 100 year storm event. CPL Response: The Designer is correct but with the number of storms approaching/greater than 100 yrs, why not install an outlet to prevent potential damage to the stormwater management facility. 15. Since pervious pavement will be installed over the existing pocket pond and infiltration area, please discuss what soil will be removed and what material will be installed within these areas. LA Group Response: Notes have been added to the plan set indicating topsoil and vegetation shall be removed below porous pavement area. Detail has been added to the plans providing a cross section through the porous pavement section. Intent is that native soil excavated as part of the new ponds and swale will be used to fill in the existing pocket pond and infiltration area. CPL Response: Include note - Please contact the City so they can observe the falling head permeability tests. Comment Addressed. 16. Modeling of the culvert in HydroCad indicates 45LF while the Record Drawings indicate 85LF. Please verify. LA Group Response:Model has been revised accordingly. CPL Response: Comment Addressed. A PB No. 20190098 May 2, 2019 Page 4 of 5 PLANS Sheet L-1.0 17. What is the purpose of the "Woods Road". LA Group Response: Woods Road is an existing condition that has been there for numerous years. Currently it is not being used. CPL Response: Comment Addressed. 18. Silt Fence should be installed parallel to contours and not just along property lines. LA Group Response: Surrounding disturbed area is flat. Silt fence is placed along edge of disturbance as there is only +/-6"change in existing elevation. CPL Response: Comment Addressed. 19. The vegetation within the pocket pond and infiltration basin should be denoted as being removed. LA Group Response: A note has been added to Sheet L-1.0 indicating topsoil and organic material shall be removed within limits of disturbance. CPL Response: Comment Addressed. 20. How will the infiltration basin be protected from stormwater runoff during construction? LA Group Response: Sheet L-1.0 has been revised to depict silt fence being placed around the infiltration basin to protect during construction. CPL Response: Comment Addressed. Sheet L-3.0 21. Please provide areas for contours associated with the pocket pond/infiltration area. A post construction survey will be required to verify the practices were constructed in conformance with the plans. LA Group Response: Bottom are of the pond and infiltration area have been added to the plans. Note all slopes are 4:1 as depicted on the plans. As-built of site improvements will be prepared as required by City of Saratoga Springs. CPL Response: Comment Addressed. Sheet L-6.0 22. Please insure all details meet the City's requirements. LA Group Response:Details are typical to previous approved City projects. CPL Response: Comment Addressed. 23. Please include a concrete washout detail. LA Group Response: Concrete washout detail has been added to the plans. CPL Response: Comment Addressed. 24. Please provide a detail for porous pavement in the areas of the pocket pond/infiltration basin. What material will be placed below the 16" depth shown in the detail provided? LA Group Response: Detail section has been added to the plans. Native material will be PB No. 20190098 May 2, 2019 Page 5 of 5 used to fill the pocket pond/infiltration basin. CPL Response: Include Note—Please contact the City so they can observe the falling head permeability tests. Comment Addressed. 25. Stone overflow weir—please define the width. LA Group Response: Width has been added to the plans. CPL Response: Comment Addressed. 26. Please define the stone size of Stone Fill (Light). LA Group Response: Stone Fill(Light) is a NYSDOT designation and represents 50-100% larger than 6" in size. "NYSDOT" indication has been added to notes. CPL Response: Comment Addressed. New Comments 27. Existing Condition HydroCad model — Subcat 3.3s, according to the existing contours is directed to the pocket pond, then infiltration. However,the model indicates it is directed to the infiltration area. Please review. 28. How was the 5 in/hr infiltration rate determined for the pervious pavement? Plans indicate to protect the existing porous asphalt parking lot. Please provide additional detail how the contractor should accomplish this? Should you have any questions, please do not hesitate to contact us. Very truly yours, CPL 4/(4,.�. • Matthew T. Smullen, P.E. Principal