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HomeMy WebLinkAbout20200205 Kaydeross Ave East Subdivision Engineering Comments 7-14-20 T'! 1 ,� GROUP .n_I•_i-r t _ ri chi r c P_C July 14, 2020 Ms. Susan Barden,AICP Principal Planner City of Saratoga Springs Planning Office 474 Broadway Saratoga Springs, NY 12866 susan.barden@saratoga-springs.org Re: Kaydeross Ave East Conservation Subdivision Dear Ms. Barden: The LA Group is in receipt of comments from The Chazen Companies regarding the Kaydeross Avenue East Conservation Subdivision application to the City Planning Office, dated June 26, 2020.The following are the responses to those comments: General Comment 1: It should be noted that an estimate of construction costs and a project narrative was not provided with this submission. Response 1: This has been provided to the City. Comment 2: The Management Plan indicates that the open space lands will be owned by the owners of Lot 1 and Lot 15, and are proposed to be managed by the City of Saratoga Springs.A maintenance agreement between the City and the property owners will need to be established if the City is willing to accept management responsibilities Response 2: The applicant's attorney has had discussions with the City attorney and maintenance responsibilities will be resolved prior to final approval. Subdivision Plans Comment 3: The Subdivision Plat must be signed/sealed by the licensed land surveyor. Response 3: A signed/sealed Subdivision Plat will be provided with the final approved drawings. Comment 4: Please provide a boundary and topographic survey map signed and sealed by the licensed land surveyor. Response 4: A signed and sealed boundary and topographic survey map will be provided with final approved drawings. Comment 5: Please label on the Subdivision Plat the minimum permeable area required as well as the maximum impermeable area allowed for each lot. Response 5: Per City Code Chapter 241-12(Conservation Subdivisions), B.5.a, "There shall be no required area, bulk, or dimensional standards in a conservation subdivision,except where such subdivision abuts an existing residence in a residentially zoned area,a suitable buffer area with suitable screening shall be required by the board." A 50-foot buffer is provided between the subdivision lots and neighboring properties. Other dimensional standards for a RR-Rural Residential district do not apply,and therefore a minimum permeable area per lot also does not apply and has not been listed on the subdivision plat. lllllllum��,.,. Comment 6: In accordance with City subdivision requirements (City Code Chapter 241,Appendix H —General Requirements and Subdivision Design Standards, Section 2-R), all applicants for proposed subdivisions are to offer the City 10%Class A Type Usable Land, or an acceptable alternative defined in the City Code. The plans do not indicate any land that has been offered to the City. Please identify how the code requirement will be met. Response 6: The applicant's position is that there is no suitable parkland and is proposing to pay the rec fee; but that is ultimate authority of the planning board. Comment 7: In accordance with City Code Chapter 241,Article IV, Section 1, Paragraph C.3,the Subdivision Plat shall identify the location, use,ownership, management, methods of preservation, and rights of the owners and the public to the open space land subject to the deed restriction. Please add appropriate notations. Response 7: Referencing the approved conservation easement will be added to the final plans. Comment 8: It appears that the existing and proposed contours are missing from sheet L-5.2 Site Grading and Drainage Plan. Response 8: The extent of topography has been extended to include the area on L-5.2 Site Grading and Drainage Plan. Comment 9: Please detail the proposed septic system layout on the plans, showing the laterals, septic tank and distribution box locations for each lot with dimensions. Response 9: A schematic septic system layout has been added to sheet L-8.4, detail 5.A detailed septic system design depicting location of laterals,septic tank,and d-box will be completed at the time building permits are issued.The septic plans submitted with the building permit are required to be signed and stamped by a professional engineer and will relate to the final location of the building. Comment 10: Indicate the proposed invert elevations of all septic system components along with top of concrete and the finished grades over each component. Response 10: See response 9. Final design plans for the septic systems will be completed at the time the building permit is issued. Comment 11: Certification and tightness testing requirements for the septic system, in accordance with NYSDOH standards, shall be indicated on the plans. Response 11: A note has been added to sheet L-8.5, Septic System Construction Notes,stating that tightness testing requirements shall be met per NYSDOH standards. Comment 12: Indicate the locations of existing and proposed utilities (gas, electric, cable,etc.)on the Utility Plans. Response 12: The final location of these utilities will be determined by utility provider. A note stating this has been added to sheet L-6.0. Comment 13: Inverts and pipe sizes of proposed driveway culverts shall be indicated on the plans to ensure sufficient cover over the pipes. Response 13: The driveway culvert detail (sheet L-8.3, detail 1) has been updated to show a required minimum cover of 12" over the culvert pipe. Final driveway and culvert locations will be determined at the time the building permits are issued. Comment 14: Proposed road geometry shall be designed such that the turn around radius of a fire truck can be accommodated. Please verify. Response 14: The maneuvers of a fire pump truck entering the site and turning around in the cul-de-sac have been added to the site layout plans,sheet L-4.0 and L-4.1. Comment 15: Based upon the City Subdivision regulations, this road could be classified as a Rural Road which requires a pavement width of 24-feet with a 55-ft ROW. The road section provided depicts a pavement width of 22-ft. Please revise the plans and update the SWPPP accordingly. Response 15: City Code Chapter 241,Appendix H–General Requirements and Subdivision Design Standards, Section 2-F provides pavement widths by street type. For small rural roads the pavement width is stated to be 20'. City Code Chapter 241-4 defines a small rural road as "a vehicular way that may be existing or shown on a plat that may incorporate the elements of a street except for curbs, gutters and sidewalks and exists within areas with a low intensity of development where natural features of the environment are highly prevalent or designed in a manner to have minimal impact to the natural features of the landscape and width of pavement is minimal." The proposed project meets these elements as it is low intensity(15 lots on a 79 acre parcel of land, 14 lots are on the new road and 1 lot is on Kaydeross Avenue)and is designed as a conservation subdivision to limit impact to the natural features of the landscape. Even though code states the road width could be 20',the applicant is proposing a 22'wide road to better align with the City standard details for the modified Rural Road. Comment 16: In accordance with the NYSDOH Appendix 75-A Wastewater Treatment Standards and the New York State Design Standards for Intermediate Sized Wastewater Treatment Systems (Design Standards), Section B.4.b, two percolations tests should be performed within the limits of each proposed sewage treatment system.Additional percolation tests should be performed in accordance with these standards. Response 16: See response 9. Final design plans for the septic systems will be completed at the time the building permit is issued,and as part of those plans two percolation tests will be performed within the limits of each proposed sewage treatment system. Comment 17: In accordance with Section E.2 of the Design Standards, conventional soil-based treatment systems should be avoided if the percolation rate is slower than 60 mpi. The soil tests provided indicate a percolation rate of"greater than 60 mpi." Please indicate the actual percolation rates on the plans to clarify if the percolation rate is slower or faster than 60 mpi. If the percolation rate is slower than 60 mpi, a conventional soil-based treatment system would not be suitable. Provide design calculations providing appropriate application rates based on soil testing to justify the size of each septic system for on each lot. It appears that the septic system areas shown accommodate seven (7)60-ft laterals at 6-ft on center. Response 17: The percolation rate is 60 mpi or slower in these locations.Since the septic system plans are schematic for this phase of development, more detailed design plans will be developed at the time the building permit is issued. This will include percolation tests in the final location of the septic field. The design footprint shown assumes a mound system is used,and that 8-10 mpi soils(specified soils that would be brought to the site)would be used. Notes detailing the design assumptions for the schematic septic systems are included on sheet L-6.2. Comment 18: Test pit results indicate seasonally high water between 16 inches and 42 inches. Please show proposed finished grade at each septic system location to ensure the required separation to groundwater is satisfied, and that the proposed mound system can fit on the site while maintaining required property line setbacks. Response 18: See response 9. Final design plans for the septic systems will be completed at the time the building permit is issued,which will require the designer to determine proposed finished grades. Comment 19: In accordance with NYSDOH standards, septic systems shall not be located where existing grades exceed a 15%slope. It appears lots 12 and 13 appear to exceed 15%slopes. Please review existing slopes on these sites to ensure the systems are not located on slopes steeper than 15%. Response 19: The proposed septic systems are anticipated to be mound type systems due to the soil properties on site. Per NYSDOH standards,existing grades in the location of mound systems must be 12% or less. The locations of septic systems have been adjusted to not be located in areas where slopes exceed 12%. Comment 20: Watertight frames and covers shall be provided on all underground structures. Response 20: Per NYSDOH Appendix 75-A, Section 6.6 Pre-cast Reinforced Concrete Septic Tanks, "All joints and drain holes shall be sealed such that the tank is watertight." Frames and covers are not included in this requirement. Please advise. — L lit _ Comment 21: As previously noted, test pits indicated seasonally high ground water between 16 and 42 inches deep. Underground structures do not appear to include any anti-flotation measures. Please provide buoyancy calculations for underground structures. Response 21: A buoyancy calculation was performed on the deepest structure identified on site, MH-1. The calculation was performed assuming groundwater is at the surface,which is extremely conservative; but it was still determined that the total weight of the manhole and soil is greater than the displaced water. The calculation is included in this submission. Comment 22: Construction details for proposed stormwater pocket ponds and wet swales shall be provided, meeting the requirements indicated in the New York State Stormwater Management Design Manual (NYSSMDM). Response 22: Construction details for the pocket ponds and wet swales have been added to sheet L-8.3, details 5, 6,and 7. Comment 23: Water mains in cul-de-sacs and dead-end streets shall be installed at a depth of six feet, per City Code Chapter 241 Subdivision Regulations. It does not appear that the proposed water main meets this requirement. Please confirm and revise the profiles accordingly. Response 23: The depth of the water main has been adjusted to show that a minimum of six feet of cover is required. Refer to sheet L-7.0. Comment 24: Proposed utilities (gas, electric, telephone)services shall be placed within the right-of-way. The final plat shall include statements that the appropriate company or agency shall approve the design for all utilities. Response 24: Per response 12,the final location of these utilities will be determined by the utility provider.A note stating this has been added to sheet L-6.0. Comment 25: Due to seasonally high groundwater conditions throughout the site, a geotechnical investigation shall be performed to evaluate whether the standard pavement section is suitable for these conditions or if a greater than standard pavement section is required. Response 25: A geotechnical investigation will be performed,and recommendations will be included in the final plans. Comment 26: Based on the profile, it appears that portions of the proposed road will be cutting into the seasonally high groundwater elevations.As such, dewatering provisions for constructing roadways and utilities in these conditions shall be detailed on the plans. In order to minimize deterioration of the road due to freeze/thaw conditions, additional provisions such as perimeter drains will need to be installed. Response 26: A geotechnical investigation will be performed,and recommendations will be included in the final plans. Engineering Report Comment 27: The water distribution system shall meet both domestic and fire flow requirements. Please provide a discussion in the report indicating the required demands are capable of being provided. Response 27: A discussion regarding a hydrant flow test conducted on site has been added to the Engineer's Report. It was determined that there are sufficient flows and pressures available to serve the proposed subdivision. SWPPP Comment 28: The SWPPP indicates that rooftop disconnect is being applied for proposed houses to treat roof runoff. According to Chapter 5 of the NYSSMDM, runoff from disconnected rooftop must be directed to a designated area that is graded for storage and infiltration of the runoff. Please indicate these areas on the plans to ensure treatment requirements (ie. length,slope,etc.)are satisfied. Response 28: Per the NYSSWDM the "disconnected,contributing impervious area shall drain through a vegetated channel,swale, or filter strip for a distance equal to or greater than the disconnected, contributing impervious area length." Locations for filter strips have been added to the plan set on sheets L-5.0, 5.1 and 5.2. — L lit _ Comment 29: It appears that subcatchments 2e1 and 3b,which are each directed to a proposed pocket pond, include the roofs of the proposed houses. The roofs are noted as being treated via roof top disconnection. Please clarify whether the roofs are being treated in the proposed pocket ponds,or treated via rooftop disconnection. If roofs are to be treated by the pocket ponds, please show the grading that ensures the roof will drain to pocket ponds. Response 29: Per the SWPPP,Appendix B(Stormwater Management Report), Section 5.2,the rooftop disconnection provided by SMP-la and SMP-2a hydrologically goes to SMP-1 and SMP-2, both pocket ponds. The treatment for the rooftop runoff is not provided at these ponds and is provided via overland flow from rooftop disconnection.As a result,the impervious area of the affected roofs is deducted from the impervious area entering the pond for treatment purposes; however,the HydroCAD model still takes this impervious area into account at the pond. This is because hydraulically it is meaningful in regards to reducing peak flow rates. An additional calculation supplement has been included in Appendix B,Attachment D,showing how the treatment calculation was modified for SMP-1 and SMP-2 to not include these roofs. Comment 30: Additional design details shall be provided for the proposed stormwater systems (pocket ponds and wet swales)to ensure the required design standards are in accordance with the design manual. Response 30: Refer to the response to comment 22. Design details have been provided accordingly. Comment 31: The proposed pocket ponds do not show the required aquatic bench with plantings. Please revise the design accordingly. Response 31: Per the NYSSMDM,Section 6.1.5. Landscaping, "the perimeter of deep pool areas(four feet or greater in depth)shall be surrounded by two benches [a safety bench and an aquatic bench.]" The pocket ponds do not have permanent pools that are greater than four feet in depth and are therefore exempt from benches. The sediment forebays are 4 feet in depth and therefore do require an aquatic bench (a safety bench is exempt due to slopes being 4:1 or flatter). Planting details are included in the pocket pond details included on sheet L-8.3, detail 5 and 6. The planting plan indicates blue flag iris in 2" plugs shall be placed in the aquatic bench at 24" O.C. Comment 32: There is an inconsistency between the size of the vertical orifice of OCS-1 indicated in the hydrocad model vs detail 8 on sheet L8.1. Please clarify. Response 32: The orifice has been updated on sheet L-8.1 to be 12"W x 3"H,which is the same as the HydroCAD Model. Comment 33: City Code Chapter 242 requires long-term maintenance of the stormwater management practices. The following notes need to be added to the SWPPP under Post-Construction Operation and Maintenance of Stormwater Control Devices: a. "All post-construction stormwater management facilities must be inspected annually by a qualified professional, a report prepared and submitted to the City Engineer documenting the inspections as well as the maintenance activities that were completed during the prior year." b. "The City of Saratoga Springs shall approve a formal maintenance and inspection agreement in accordance with City Code Chapter 242 for stormwater management facilities to ensure the practices will be properly operated and maintained in accordance with the long-term operation and maintenance plans. This agreement shall be binding on all subsequent landowners and recorded in the office of the County Clerk as a deed restriction on the property."A draft maintenance agreement should be provided and shall be reviewed by the City and City's counsel. Response 33: a. This note is already included in the SWPPP under Section 1.0 Permit Overview and Requirements,fourth paragraph. b.A draft maintenance agreement has been created and shall be reviewed by the City and City's Counsel. The agreement is included in Appendix E of the SWPPP. Sincerely, Douglas B. Heller, PE,ASCE Associate Principal Director of Civil Engineering/ Civil Engineer dheller©thelaq roup.com G:\Proj-2016\2016109 Scott KayderrossAve\2016109Admin\01Correspondence\2.7Review Comments\2020 06-30 Comment Response Ltr. 2016109-hafrev 1.docx