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HomeMy WebLinkAboutCrossRoads Response 03.12.20    March 12, 2020 Willie Hall CrossRoad Engineers, P.C. 3417 S. Sherman Drive Beech Grove, IN 46107 RE: Bear Creek South Docket No. 17040018 SP Amend Dear Willie, Please find enclosed 1 set of revised Final Plats (Section 1A & 1B), Construction Plans, O&M Manual, and Drainage Report for Bear Creek South. The plans have been revised per your comment letter dated March 5, 2020. I have addressed each of your items individually with a numbering system consistent to your comment letter. Drainage 1. Per Section 102.02 of the Stormwater Technical Standards Manual (STSM), the current revision date shall be indicated on all sheets in the construction plans. See comments in bold and italics below. Noted. Revision date added to plan sheets. 2. Addressed satisfactorily. Noted. 3. Addressed satisfactorily. Noted. 4. Addressed satisfactorily. Noted. 5. Addressed satisfactorily. Noted. 6. Addressed satisfactorily Noted. 7. Addressed satisfactorily Noted. 8. Addressed satisfactorily. Noted. 9. Per Section 302.05 of the STSM, the following: a. Addressed satisfactorily. b. Addressed satisfactorily. c. Addressed satisfactorily. d. The offsite runoff may be routed through the detention/retention facility, provided that a separate, secondary outlet system is incorporated for the safe passage of such flows, i.e., not through the primary outlet of the detention facility. Structure 604 (primary outlet) is not to be utilized as the secondary outlet for offsite flow through the pond. Please review and revise. Per call on 3/10/20, the primary outlet is the 24” RCP pipe and the secondary outlet is the spillway. The top of box is set at the onsite 100yr elevation and the spillway elevation is set roughly 0.8’ higher based on site elevation challenges. Per our call, Crossroad Engineers will discuss with Carmel for acceptance based on challenging circumstances related to the site and outfall. No revisions have been made. 10. Addressed satisfactorily. Noted. 11. Per Section 302.07.4 of the STSM, methods to prevent pond stagnation, including but not limited to aeration facilities, should be considered on all wet-bottom ponds. Design calculations to substantiate the effectiveness of proposed aeration facilities, and any impacts on the effectiveness of the pond’s use as a stormwater BMP shall be submitted with final engineering plans. Agreements for the perpetual operation and maintenance of aeration facilities shall be included in the restrictive covenants of the development or as provided by policy or codes. The legend on the Development Plan Sheets indicate that a “fountain/bubbler” is proposed for each pond. The detail on Plan Sheet C8.2 indicates a floating fountain is proposed. Please provide details and specifications of what type of system is being proposed for each pond, and design calculations as directed above. This information is to be included in the O&M Manual as well. Design calculations to substantiate the effectiveness of proposed aeration facilities, and any impacts on the effectiveness of the pond’s use as a stormwater BMP shall be submitted with final engineering plans. There are no aeration facilities proposed, only the 24-hour requirements for an aeration system is provided. Please revise to include proposed facilities, the effectiveness of the proposed facilities with regards to the 24-hour requirements listed, and the impacts that the aeration facilities will have on the effectiveness of the pond’s use as a stormwater BMP Fountains have been removed from the construction plans, Drainage Report and O&M Manual. Aquamaster AquaAir Ultra aeration units have been designed and selected. The Drainage Report narrative has been updated with the design information and Appendix H for the calculations from vendor. Construction Plan Sheets C1.1-C.6 have been updated to provide the aeration unit type and design information. Details have been added to C1.11. O&M Manual has been updated to include the aeration units in the BMP Location Exhibits and Product Information. 12. Per Section 501.01 of the STSM, there should be no less than 2.5 feet of cover along any part of the pipe from final pavement elevation or final ground surface elevation to the top of the pipe. Please review Structures 604, 604A, 605, 605A, 620, 621, 628, 629, 630, 638, 639, 646, 663, 658, 659, 676 and 677. Approval subject to favorable review of Drainage Waiver Request dated December 11, 2019. Noted. 13. Per Section 302.12.7 of the STSM, where the outfall from the stormwater drainage system of any development flows through real estate owned by others prior to reaching a regulated drain or watercourse, no acceptance shall be granted for such drainage system until all owners of real estate and/or tenants crossed by the outfall consent in writing to the use of their real estate through a recorded easement. This applies to the easement for the outlet storm structures across the “Pegram” property (Plan Sheet C1.6). Discussions with the City of Carmel, the proposed easement width shall be 15 feet outside each run from the center of each run, plus the width between the two runs measured from the center of each run. Scaling, it appears an additional 5 feet along the east side of the proposed easement is required. Revisions to the easement width made as requested; approval of drainage subject to Section 302.12.7 of the STSM. Has an easement been secured, and has this easement been submitted to the City of Carmel Engineering Department? Please provide a copy of the executed easement in the next submittal. Noted. Pulte Homes is in the final stages of securing the easement and will provide once secured. The Construction Plan approval (or resolution to review comments to be in position to be approved) is important inconjunction with executing the easement agreement to ensure no additional changes. Please acknowledge when review comments have been addressed satisfactorily. The project will not be released into construction until easement is provided. 14. Addressed satisfactorily. Noted. 15. Addressed satisfactorily. Noted. 16. Addressed satisfactorily. Noted. 17. Per Section 501.03 of the STSM, a minimum drop of 0.1 foot through manholes and inlet structures should be provided. Please review Structures 603, 603A, 604, 604A, 605, 605A, 611 and 612. Approval subject to favorable review of Drainage Waiver Request dated December 11, 2019. Noted. 18. Addressed satisfactorily. Noted. 19. Addressed satisfactorily. Noted. 20. Addressed satisfactorily. Noted. 21. Addressed satisfactorily. Noted. SWPPP 22. Please provide a wetlands delineation. Aerial photography indicates inundated areas within the limits of the site. Please include a copy of the information shared with John Thomas in 2017 as a part of the next submittal. The response is the areas have been noted and directed to do not disturb; however, Plan Sheets C1.1 and C1.2 both show the wetland areas to be removed. The permits for this work will need to be provided. Please review and revise. On March 6, 2020 via email, correspondence was provided with John Thomas and Alex Jordan with the City of Carmel between V3 Companies and the Army Corps/IDEM. Army Corps has made a formal determination (Approved Jurisdictional Determination) they will not regulate the exempt wetlands. IDEM has confirmed the northeast wetland is incidental and the southwest wetland is isolated and will be exempt based on classification and size. A formal letter from IDEM is being prepared. Both wetlands will be exempt. 23. Addressed satisfactorily. Noted. 24. Addressed satisfactorily. Noted. 25. Addressed satisfactorily. Noted. 26. Addressed satisfactorily. Noted. 27. Addressed satisfactorily. Noted. 28. Addressed satisfactorily. Noted. 29. Addressed satisfactorily. Noted. 30. Addressed satisfactorily. Noted. Engineering 31. Please provide an anticipated start construction date. Noted. Construction is planned to start no later than April 1, 2020. The goal is to resolve any remaining comments and be released no that than that start date to avoid having the awarded contractor remove it from their spring/summer schedule resulting in significant delays. 32. Until the construction plans are approved, the current revision date shall be indicated on all plan sheets. See comments in bold and italics above and below. Noted. Revision date added to plan sheets. 33. Addressed satisfactorily. Noted. 34. Addressed satisfactorily. Noted. 35. Addressed satisfactorily. Noted. 36. Addressed satisfactorily. Noted. 37. Addressed satisfactorily. Noted. 38. Addressed satisfactorily. Noted. 39. Addressed satisfactorily. Noted. 40. Addressed satisfactorily. Noted. 41. Addressed satisfactorily. Noted. 42. Addressed satisfactorily. Noted. 43. Addressed satisfactorily. Noted. 44. Addressed satisfactorily. Noted. Additional Comments 45. Per Section 102.02.xi.f, please include proposed topographic information at one-foot contour interval based on NAVD 1988. Additional topography will be required along the north site boundary of the entire site, the rear of Lots 109-112, and the rear of Lots 102-104, to confirm that ponding will remain within the limits of this project in accordance with Section 303.07, and that the proposed system will accommodate the drainage issues along the north side of Lots 112 and 113. The proposed topographic information at one-foot contour interval based on NAVD 1988 is not complete. There are still no proposed contours that show how the swale along the backs of these lots will tie into existing contours. Please review and revise. Construction Plan sheets C1.4 and C1.5 have been updated to include proposed contours tying into existing contours. Please note the swale is cut into grade and the north line is relatively flat, given the amount of information in these locations the contour lines might be difficult to read however they match existing within this development site. There are numerous beehive storm inlets along the north line to waffle the swale to keep it lower and accept any incidental runoff from the north 46. Addressed satisfactorily. Noted. 47. Per Section 701.05, the City of Carmel requires all water leaving a site shall be treated by a minimum of two BMPs as part of a stormwater quality management system. At least one of the BMPs must be capable of removing the major pollutants identified in the Storm Water Pollution Prevention Plan. C1.3, C1.6, C6.3 and C8.2 have been revised. Storm structure #627 has been modified to a diversion manhole and a mechanical unit (AS-4) has been added to provide second treatment to this storm network. If you have any questions or require additional information, please feel free to contact me at your convenience. Sincerely, Brandon T. Burke, P.E. Senior Project Manager Enclosure