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Home My WebLink AboutSDP200800098 Review Comments Final Site Plan and Comps. 2009-03-09 (3)� OF AL ,. vIRGI1`IZP COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902 -4596 Phone (434) 296 -5832 Fax (434) 972 -4126 Project: Montessori Community School [SDP200800098, WP0200800065] Plan preparer: Alex Forast6 [email: aforaste @mckeecarson.com] Owner /Applicant: Wendy Fisher [email: wendyfisher@montessoripantops.co received date: 11 June 2008 Rev 1: Rev 2: Date of comments: Rev 1: Rev 2: Reviewer: Rev 1 &2: 2 October 2008 4 February 2009 29 July 2008 24 November 2008 9 March 2009 Jonathan Sharp John P. Diez — Engineering Technician A. Final Site Plan — Phase 1 1. All final site plans and stormwater management plans require a professional seal, signed and dated. [18- 32.6.1] (Rev. I) Comment has been addressed 2. Proposed slopes steeper than 3:1 require low- maintenance (not grass) ground cover specified on the plans. [DM] (Rev. I) Comment has been addressed 3. The proposed guardrail should be extended 40 -50 ft north along the steep slopes for safety. [ 18- 32.7.2] (Rev. I) Comment has been addressed 4. The following ordinance requirements are not met for the temporary parking area: [ 18 -4.12, DM] a. proposed parking spaces exceed 5% in slope (Amelia) b. proposed travelways exceed 10% in slope (no) c. proposed parking area does not meet surface material requirements (no) d. curb and gutter is not proposed on all parking /travelway areas (Amelia) e. sidewalks are not concrete, do not maintain 5' in width (Amelia) I understand that the proposed parking area is temporary. However, waivers must be approved in order to approve the site plan as shown. I cannot find any previous waivers addressing these items. Please provide copies of existing waivers addressing the proposed parking layout, if any. Otherwise, please submit a waiver request, or meet all ordinance requirements. If required, the waiver process is administrative (does not require Planning Commission action.) (Rev. l) Comment has not been addressed. The five waiver requests have been denied. The existing non - conforming parking may remain in its current state. Any changes to the parking, including additional parking or realignment of the spaces is required to meet the ordinance requirements. (Rev. 2) Waiver has been withdrawn. Albemarle County Community Development Engineering Review Comments Page 2 of 4 5. A portion of the parking area drains uncontained down the steep hillside as it bypasses the proposed curbing. Please direct all drainage away from the steep hillside to avoid potential drainage and erosion problems. [18- 32.6.6d] (Rev. I) Comment has not been addressed. Please provide proposed curbing all the way to the southwest corner of the parking lot. (Rev. 2) Waiver has been withdrawn. 6. Typical sections for proposed channels with locations referenced from plan view sheets are required on the plans. [DM] (Rev. I) Comment has been addressed. However, please be advised that the section is D -8, not C -8. 7. The Albemarle County general construction notes are required on the plans. [DM] (Rev. I) Comment has been addressed 8. Grate types for drop inlets must be specified on the plans. [DM] (Rev. I) Comment has not been addressed. We cannot endorse product brands. Please add "....or approved equal" to this note. (Rev. 2) Comment has been addressed 9. Roof drain locations, profiles, and calculations are required. See also comment 12. [DM] (Rev. I) Comment has not been addressed. We are concern that the gutter system will not hold a 10 year storm; hence, not making it to the cistern. (Rev. 2) Comment has been addressed 10. Drainage profiles for proposed channels, existing pipes, and proposed pipes must be provided on the plans. [DM] (Rev. I) Comment has been addressed 11. Drainage computations are substantially incomplete. The drainage areas provided for the pipe computations are incorrect. Inlet drainage area maps are required. Drop inlet calculations are required. Culvert calculations are required. Ditch computations are required. Outlet protection calculations are required. [DM] (Rev. I) Comment has not been addressed. Culvert calculations are needed for EX -l. Drop inlet calculations are needed for ADS inlets to show that appropriate head over the grates have been provided for at each structure. (Rev. 2) Comment has been addressed B. Stormwater Management Plan 12. In order to utilize the cistern for detention, details and calculations for the gutter system must be provided to ensure that the system will actually convey the 2 and 10 year storm into the cistern. If the 2 and 10 year storm does not make it into the cistern, the cistern is not providing any detention. Detention storage and routings must be over and above the assumed initial storage volume and the required stormwater quality volume (i.e., storage and routing begins above assumed volume of 40% and also above the required water quality volume, in this case about 7 cu yds, or about 1500 gallons. [DM] (Rev. I) Please also see Comment 9. Generally, the building code standards that buildings are designed for do not pass storm intensities of 6.7 in /hr. If detention is provided for in the cistern, you must show that the rooftop system is sized to pass such a storm. The routing must be started at the water quality elevation assuming that the area for water quality is full. (Rev. 2) Comment has been addressed Albemarle County Community Development Engineering Review Comments Page 3 of 4 13. No details of the cistern have been provided. Cistern details are required, matching stormwater computations. The details should be to scale, provide all invert elevation information, outlet structures, etc. An adequate depth of soil cover should be provided over the facility. [DM] (Rev. 1) Comment has not been addressed. Please provide more graphical information for the orifice inverts. (Rev. 2) Comment has been addressed 14. It appears that the overflow pipe for the cistern will be running uphill. [DM] (Rev. 1) Comment has been addressed 15. The routing model and results are required for the cistern. No hydrographs have been provided. [DM] (Rev. 1) Comment has not been addressed. Your routing does not match your plan cistern overflow. (Rev. 2) Comment has been addressed 16. The critical duration computations are incorrect. The calculations provided in the VSMH are only for preliminary facility sizing, and are not based on the facility volume or outlet structures. The critical duration storm is also dependent on the areas bypassing the facility (as you are calculating the critical duration storm causing the peak rate of runoff for the entire watershed, not simply the facility). In this case, the area bypassing the facility represents 95% of the drainage area. In cases like this, the critical duration storm that represents the peak rate of runoff over the watershed will almost always be 0 minutes (because almost all of the runoff is unrouted, and the peak rate of runoff for an unrouted watershed always occurs at a critical duration of 0 minutes). [DM] (Rev. 1) Comment has been addressed. 17. Albemarle County general stormwater notes are required on the plans. [DM] (Rev. 1) Comment has been addressed 18. The stormwater maintenance agreement associated with Montessori School may need to be updated. The proposed SWM facility appears to be located on TMP 12A. Please contact Pam Shifflett to verify whether or not the agreement requires to be updated. (Rev. 1) Comment has been addressed 19. A SWM bond will be computed by the County once the plans have been approved. Please provide a cost estimate for the proposed cistern. (Rev. 1) Comment has been addressed C. Erosion and Sediment Control Plan 20. The limits of clearing and grading must include all proposed demolition. [DM, VESCH] (Rev. 1) Comment has not been addressed. (Rev. 2) Comment has been addressed 21. A parking area, staging area, and stockpile location are required. [DM] (Rev. 1) Comment has been addressed 22. The embankment for the proposed trap must be flat. [VESCH] (Rev. 1) Comment has not been addressed. (Rev. 2) Comment has been addressed Albemarle County Community Development Engineering Review Comments Page 4 of 4 23. An adequate channel analysis [MS -19] must be provided for the site. The existing pipe system from structure OF -3 to the outfall into the Luxor Pond must be analyzed for adequacy. Existing drainage structure information and drainage area maps should be included with the approved Pavilions at Pantops Site Plans and Luxor Road and SWM plans, and can be made available upon request at the County Office Building Department of Community Development. [DM, VESCH] (Rev. I) Comment has not been addressed. Please verify drainage area of the pipe system for Rolkin Road. (Rev. 2) Comment has been addressed 24. An ESC bond will be computed by the County once the plans have been approved. The Erosion & Sediment Control and Stormwater Management Plans submitted 4 February 2009 have received Engineering Review and meet Albemarle County minimum checklist items for approval. Please submit 5 paper copies of the Plan to Current Development Engineering. The E &SC bond amount is $18,100. The SWM bond amount is $54,784 E3_fsp, esc, swm_JPD_Montessori Community School