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Home My WebLink AboutSDP202200012 Review Comments Initial Site Plan 2022-04-01qoa nt 401 McIntire Road, North Wing Charlottesville, VA 22902-4579 County of Albemarle o � � Telephone:434-296-5832 COMMUNITY DEVELOPMENT DEPARTMENT WWW.ALBEMARLE.ORG �tBGIN��' Site Plan review Project title: River's Edge Initial Site Plan Project file number: SDP202200012 Plan prepares Shimp Engineering, 912 E. High St., Charlottesville, VA 22902 Michael Chandler, michael(i�shimp-engineering.com Owner or rep.: Rivers Edge Holdings, LLC / P.O. Box 6458, Charlottesville, VA 22906-6458 tomatweeksAgmai1. com Plan received date: 14 Mar 2022 Date of comments: 1 Apr 2022 Plan Coordinator: Ben Holt Reviewer: John Anderson Engineering has reviewed the initial site plan and offers these review comments for Final Site Plan approval. SDP2022-00012 1. CIO: Recommend label trail features presently not labeled. 2. C11,C12,C13 a. Show Aabel steep slopes. Additional comments possible, once steep slopes overlay shown. b. (CU3 Ensure Engineered level spreader meets design criteria for downslope Max. grade /Min. slope length listed in VA DEQ Storrnwater Design Specification No. 2, Table 2.2. Alternatively, replace ELS with detention that attenuates concentrated storm runoff release at this discharge point. c. 14 Apr 2020 ZMA Application Plan, sheet 20, Note 2 states: `If permitted under applicable stormwater regulations, stormwater discharge may be to level spreader or similar facility to open space. If conditions do not permit such discharge, stormwater may be conveyed to the stream or river in an adequate channel (shown in gray) with slope stabilization as applicable, where stream bank disturbance occurs.' Conditions likely do not permit ELS; with WPO plan, ensure proposed drainage /SWM meet VDOT /BMP Clearinghouse Min. standards, design criteria, etc. A possible alternative to ELS is detention pipe along site access /travel way, with gradual release of detained flow via storm pipe down /across preserved slopes to stream, or river. Also, item 2.b. above. d. Submit WPO Application /plan at earliest convenience. WPO plan approval is required for final site plan approval. e. SWM facility easement (plat /deed) recordation is required prior to WPO plan approval. f. Provide private access easement to connect U.S. Rt. 29 with residential development. 3. C4-05-C6(andCll-C12-C13) a. Show and label FEMA mapped floodplain. b. Show and label GIS stream buffer overlay. 4. C12 a. Retaining walls >3-ft. ht. require a building permit and must include safety railing. b. Retaining walls >4-ft ht. require PE -sealed geotechnical plans. c. Proposed retaining walls along site access require VDOT GR-2 guardrail (unrecoverable slopes, vertical drop), provide GR-2 and ensure retaining wall (PE -seal design), roadway construction, and GR-2 installation all conform with VDOT standards for guardrail type (web/post), rail post spacing, terminal treatment, horizontal clearance to back -slope, etc. d. Submit retaining wall PE -sealed plans that show GR-2 to Engineering prior to /as condition of final site plan approval. Engineering Review Comments Page 2 of 3 5. C8, C9, C10 a. Label sanitary pump station with wet well. b. Provide sight distance profile south/left at U.S. Rt. 29. c. Provide Name for site access /travelway for a-911 purposes. d. Obtain VDOT Land Use permit for work within U.S. Rt. 29 RW. e. Show proposed sanitary connection with Ex. RWSA /ACSA facility at U.S. 29. f. If road bore required beneath U.S. Rt. 29 for utility purposes, provide notes, details, schematics, graphics, Notice to Contractor etc. concerning safe utility operation within VDOT RW, or as required by ACSA /RWSA to meet utility /Agency requirements. g. Coordinate all aspects of site /entrance work at U.S. Rt. 29 (within RW) with VDOT. A MOT may be required. h. Provide posted /advisory speed limit sign/s on site access. i. Provide `No parking' sign/s at intervals along site access. j. Recommend `Yield' signs to establish thru movement. k. Design site entrance culvert pipe to pass the 25-yr event. 6. C11,C12,C13 a. Show Aabel ACSA sanitary sewer /water line easements. b. Label all retaining walls. Assign Wall identifiers (letter, #) for ease of reference. Provide TWBW elevations. c. (Cl 1) Provide suitable ditch runout for 6' travelway ditch at U.S. Rt. 29. Design must avoid and limit potential erosion at U.S. Rt. 29, or other locations. Further, this point discharge must meet state stormwater management (stormwater quantity) regulations. d. (C12) Engineering prefers design abandon ditch to Rt. 29, and instead, more nearly approximate design shown on sheets 20,21 of 14 Apr 2020 ZMA Application plan, which shows no conveyance to U.S. Rt. 29 RW. e. (C13) Revise proposed 340 LF 108" CMP underground detention system which presents liability, with few if any positive offsets (perhaps less initial expense). Unless rock precludes multiple smaller systems, installation of proposed 340 LF 9' DIA system will require significant SWM facility easement width (Ref. ACDSM Easement diagram, p. 15), which requires, for a system this size, at least 37' wide SWM easement (assume 1' bedding, 3' cover). In the future, when the system is replaced, there will be no vehicular access to the entire lower parking area that serves nearly half the Rivers Edge development. Also, should there be performance issues with a single detention system, there is no backup to treat a portion of developed runoff. If the proposed single system is bypassed, it is possible the entire volume of impervious area runoff could route across preserved steep slopes. ZMA Application plan sheet 19 presents a system approximately half the length proposed. Propose alternate detention that maintains partial access to lower parking lot should future circumstance warrant excavation of parking areas to repair or replace the UG detention system. Consider alternative SWM design that locates multiple detention practices nearer to residences and upper tier parking (for example, 4 — 85 LF systems would provide identical detention capacity without compromising access to this degree, and would permit at least partial water quantity treatment should incident affect one of several systems. As it is, incident affecting a single system may prevent or compromise storm detention, entirely. Engineering disapproves current proposed SWM design on access /maintenance basis, as well as scale of departure from ZMA Application plan. With WPO plan, provide bypass of any SWM facility while mitigating impact of bypass flow to critical resources, especially preserved steep slopes. f. Provide CG-6 or CG-7 along site access/travel way wherever storm runoff concentrates against curb. If ZMA approval explicitly exempts site from curb -gutter requirements at Ch. 14 /18, please direct Engineering to exemption. Otherwise, please see 18-32-7.2.2.a. / 14-412.B., provide curb with gutter.[Note: sheets 20-22 of ZMA Application plan show inlet design along site access.] g. Provide PE -sealed sanitary effluent pump station design, incl. pump curves, pump type, wet well design, alarms, remote sensing, etc. as provided with documents or during presentation to PC or BOS in 2020, or in /with ZMA documents, etc. Recommend furnish evidence of coordination or approval with or from DEQ, relative to sanitary pump station design. Albemarle will not review Engineering Review Comments Page 3 of 3 or approve pump station design. ACSA is unlikely to review or approve pump station design. It is incumbent upon developer (per approved ZMA) to obtain approvals needed to construct the pump station, to ensure remote sensing system is operational, and that station will be maintained. 7. C 15: Show proposed storm lines and utilities (sanitary sewer/water) in light line -type on this sheet, to highlight potential conflicts. For example, proposed storm lines are proposed to cross at least 5 parking islands proposed to be planted with large canopy species. Revise storm pipe locations to avoid landscape conflicts. 8. Ensure steep slopes disturbance is consistent with sheet 23 14 Apr 2020, ZMA Application, and does not exceed 39,100 sq. ft. approved with ZMA. Show /label Area (ft) of Preserved Steep Slope impact with WPO and ESP. 9. Ensure stream buffer disturbance is consistent with sheet 24 14 Apr 2020, ZMA Application, and does not exceed—23,000 sq. ft. approved with ZMA. Show Aabel Area (ftz) of stream buffer impact with WPO and ESP. 10. C 14: Public drainage easement (downstream of SWM) should not propose storm pipe beneath /through a retaining wall. If unavoidable, provide concrete headwall Aintel details with PE -seal, similar to Versa-Lok Tm standard. Comment does not anticipate approval of public drainage easement with pipe penetration beneath or through a retaining wall, a configuration to avoid. 11. C 16: Include Site Access (travelway) section with stone /pavement depths, see River's Edge Street Section, sheet 28 of ZMA Application plan. Provide site access pavement design based on full buildout ADT. 12. Provide VDOT LD-229 (storm drain design computations) and LD-204 (stormwater inlet computations). 13. Provide complete storm profiles with labels, rim ANV elevations, slope, DIA, compaction notes, etc. 14. Provide road profile generally consistent with ZMA Application plan ZMA201800018, sheets 17, 18 (revised 14 April 2020) with smooth vertical curves, K-sag /crest values (sufficient sight distance), etc. Please feel free to call if any questions: 434.296-5832 -x3069 Thank you J. Anderson SDP202200012 River's Edge ISP 040122.docx