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Home My WebLink AboutWPO201500072 Correspondence 2015-10-05 CARSONXit ENGINEERS 0 SURVEYORS 0 PLANNERS October 5, 2015 John Anderson County of Albemarle Dept. of Community Development 401 McIntire Road, Room 227 Charlottesville,VA 22902-4596 Project: Bridlespur Farm Project Number: WPO201500072 Mr.Anderson, This letter is in response to your comment letter dated October 1, 2015 regarding the above- referenced Erosion Control Plan. In the letter you provided plan review comments on varies item through the plan.The following are the review comments, followed by our responses to those comments. Please note that 2 new sheets have been added to the plan. I reworked the SWM to eliminate the permeable pavers and update all the TR-55 &VRRM calculations. A. Stormwater Pollution Prevention Plan (SWPPP) The SWPPP content requirements can be found in County Code section 17-405. A SWPPP must contain (1) a PPP, (2) an ESCP, (3) a SWMP,and (4)any TMDL measures necessary. 1. SWPPP—Provide 11" x 17" Exhibit. Recommend ESC Plan as template. Show solid/non-hazardous waste dumpster; sanitary facilities(port-a-john); solvent-paint storage; concrete wash-out; on-site fuel storage. DEQ, during periodic inspections of active projects, instructs on importance of an Exhibit that shows location of these features. All should drain to containment. For example, silt fence downstream of Aort- a-john. Concrete wash-out, dumpster draining to trapping device (lined, in case of concrete wash-out). On-site fuel storage berm with 10m1 liner, sized to hold fuel volume+2 yr. storm event. .PDF samples available. Exhibit is not intended as a detailed design, but to show containment and locations which may change over time. Exhibit is a construction aid and resource protection/inspection management tool. An SWPPP exhibit has been provided with the SWPPP items shown. Instead of 11x17 exhibit, a 24x36" exhibit was prepared so that is readable and could be updated as needed B. VSMP:SWPPP:Stormwater Management Plan (WPO201500072) VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a SWMP. This plan is disapproved for reasons provided in comments below.The stormwater management plan content requirements can be found in County Code section 17-403. 1. Title—Include reference to VSMP WPO201500072. The VSMP reference number has been added to the cover/title plan. 2. Title—Add SWM Plan sheet to index. A SWM/BMP plan sheet has been added to the plan index. The new sheet has been numbered as 6A. çARsos A SHLEY ENGINEERS o SURVEYORS o PLANNERS 3. Create SWM Plan sheet. Remove ESC measures,and highlight roof leaders to cistern, 8'grass channel, and permeable/open pavers. A new sheet has been created and the ESC controls removed and the BMP highlighted and labeled. See sheet 6A. 4. On this SWMP, confirm that permeable/open pavers are IP(interlocking pavers). Label IP. With the knowledge that Castlerock will be installing a 60K gallon cistern, I went ahead and re- evaluated the VRRM and storm water calculations. I decided with the size of the cistern that the permeable pavers are not truly needed to aid in water reduction.Additional calculations has been added to show that the cistern is more than adequate for the proposed development.See sheets 8-10. 5. Permeable/open pavers: Show where underdrain daylights/plan view. Provide underdrain INV out. Permeable pavement no longer proposed;therefore the comment no longer applies. 6. Permeable/open paver calculations: Ref.Table 7.4,VA DEQ Stormwater Design Specification No. 7,which outlines different design requirements for three scales of permeable pavement. Project proposes -9,467 SF(3,685+47'x 123'). Table. 7.4 requires two soil tests per practice for small-scale pavement. Provide field-verified infiltration rates. Text, p. 11, indicates testing is required for design without an underdrain. If infiltration/drain field data is available, use measured infiltration rates. If not available, please furnish at least one test in proposed permeable/open pavement location. Permeable pavement no longer proposed;therefore the comment no longer applies. 7. Revise Eq.7.1,sheet 10, using Field-verified infiltration rate,variable i(ft/day). Permeable pavement no longer proposed;therefore the comment no longer applies. 8. Revise Eq.7.2, sheet 10, using Field-verified infiltration rate,variable i(ft/day). Permeable pavement no longer proposed;therefore the comment no longer applies. 9. Revise Eq. 7.3, sheet 10: use k=100 ft/day(BMP assumed value). Permeable pavement no longer proposed;therefore the comment no longer applies. 10. Equation 7.4—recalculate depth of reservoir layer(ft.)to reflect revised Eq. 7.1, 7.2, 7.3. Permeable pavement no longer proposed;therefore the comment no longer applies. 11. Revise open paver cross-section to reflect items 6-10,above. Permeable pavement no longer proposed;therefore the comment no longer applies. çARsoNAsHLEY ENGINEERS 0 SURVEYORS o i'E.ANNERS 12. Provide observation well. Ref. p. 14, Spec. No. 7. Also Table. 7.5. Permeable pavement no longer proposed;therefore the comment no longer applies. 13. Revise open paver cross-section (sheet 10) bedding course to specify 2 in.depth of No.8 stone over 3 to 4 inches of No. 57. (Spec. No. 7,Table 7.5) Permeable pavement no longer proposed;therefore the comment no longer applies. 14. Open paver cross-section: Revise leader line arrow for perforated pipe so that it points to perforated pipe. Permeable pavement no longer proposed;therefore the comment no longer applies. 15. 8' Grass channel: Provide cross-section on SWM Plan sheet. A cross section of the 8'grass channel has been added to sheet 68. 16. Recommend pretreatment for 8'grass channel. Ref. p. 13,Sec. 6.3,VA Stormwater Design Spec. No. 3. A gravel or stone diaphragm along the edge of the pavement shall act as a pre-treatment see the ESC and SWM plan. Details have been added to the SWM/BMP detail plan sheet.See sheet 68. 17. Provide(transfer critical) installation and maintenance information to plan to aid construction and periodic inspection. Ref. DEQ Stormwater Design Specification No. 3,Sec. 8,Sec.9. Design Specifications have been added to sheet 68 18. Cistern: Provide plan/profile (not overly detailed). Show depth/relationship to roof runoff collection. Approximate inverts have been added to the roof drains at the ends and junction points.A profile of the cistern has been added to sheet 68. 19. Cistern: Provide system installation and maintenance information to aid construction and inspection. (Also, item 17, above) The cistern information from the clearing house standards have been add to sheet 68 20. Pavers: Provide Clearinghouse installation and maintenance information to aid construction and periodic inspection. (Also, item 17,above) Permeable pavement no longer proposed;therefore the comment no longer applies. 21. Sheet 5 (on SWMP): Label area (SF) stable&equestrian barn roof that will drain to the cistern. The area of the roof draining to the cistern has been added to sheet 6A. çARsoNAsHLEY ENGINEERS o SURVEYORS 0 PLANNERS 22. Sheet 5 (on SWMP): Label length of 47' wide permeable open pavers. Permeable pavement no longer proposed;therefore the comment no longer applies. 23. Sheet 5 (on SWMP): Label length of proposed 8' wide swale (grass channel). The length of the grass swales have been added to 6A. 24. Sheet 5: Provide cross-section for proposed 6' drainage swale,depth/slope. A cross section, construction information and calculation have been added to sheet 68 25. Sheet 5: Show cross-section detail for proposed San. Line pipe encasement at stream crossing. Spec. encasement. A basic detail for a steel casing for the sanitary service line has been added to sheet 4. 26. Sheet 5: Remove 458' contour on 47'wide pavers. Spot elevations indicate paver Elev.<458'. As the pavers are no longer proposed the contour shall remain showing a slope on the parking area that will drain to the grass swale. 27. Sheet 6: Misprint at proposed CuIv. Calc:Q10 per pipe =42.3/2=21.15 cfs, should read Q2. The misprint has been revised to read Q2. 28. Sheet 7: Revise CN worksheets: 2.75 Ac. C soils, 25.25 Ac. B soils. [ref. email: 9/30/2015 4:13 PM] I review the information sent on the hydrologic soils and have revised the CN worksheet on sheet 7. 29. Sheet 7: Revise Scale in Feet(1" =400'). Plan scale is 1" =200'. The plan scale has been updated to match the plan and bar scale. 30. Sheet 9: P1, P2, P10,Charlottesville,VA: 3.0, 3.7, and 5.6. Revise TR-55 Calculations. [http://hdsc.nws.noaa.gov/hdsc/pfds/pfds map cont.html?bkmrk=va I revised the P1, P2,&P10 in the TR-55 and the VRRM calculations. C. VSMP:SWPPP: Erosion Control Plan (WP0201500072) Virginia Code§62.1-44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This plan is disapproved for reasons provided in comments below.The erosion control plan content requirements can be found in County Code section 17-402. CNCARSON XbASHLEY ENGINEERS 0 SURVEYORS o PLANNERS 1. Sheet 5: Label Area to be Disturbed, =3.00 Ac. (General VPDES Permit Registration) The limits of disturbance has been added to sheet 5. With the locations of the cistern being added the amount of disturbance has increased by X acre to 3.50 acres 2. Sheet 3: Add Albemarle County General Construction Notes(1.-9.); General Construction Notes for ESC Plans(1.-20.) Attached Link: https://www.google.com/url?a=http://www.albemarle.org/upload/images/forms center/departments/C ommunitv Development/forms/Engineering and WPO Forms/Engineering Plan Review General Note s Feb2014.pdf&sa=U&ved=OCAQQFIAAahUKEwilu4i36J IAhUBMz4KHfRWBxM&client=internal-uds- cse&usg=AFQICNFIcT4iS4rxYi8edBJdRKOWGPh2vw The Standard Albemarle County General Construction listed above have been added to sheet 3. D. VSMP: Mitigation Plan The mitigation plan requirements can be found in County Code section 17-406 1. Sheet 11:Avoid San. Line to drain field. Provide clearance between Mitigation plantings and San. Line. The planting has been adjusted to maintain a 10'clearance from the sanitary sewer line to the drainfield.See sheet 12 for the location of the planting in relation to the sewer line. 2. Sheet 12/Understory Evergreen table: 6" high should read 4' high. —Ref. Restoration Establishment Table B. Attached. The understory evergreens size has been updated to read 4'high.See sheet 12. Should you have any questions please regarding our responses, please do not hesitate to contact me at 540-347- 9191 or by e-mail at cschumacherPcarson-ashlev.com Respectfully submitted, CARSON,ASHLEY&ASSOCIATES, LLC avaSchuncie By: Carol Schumacher, Engineering Technician Enclosures Todd Shifflett From: Gretchen Yahn <gey@ceicountry.com> Sent: Tuesday, September 22, 2015 2:09 PM To: Todd Shifflett Cc: Danielle Roth; Emily Lantz; John Anderson Subject: Re: Bridlespur Farm -WP0201500072 Todd: Thank you for the email. Per my discussion with you,we are meeting John Anderson tomorrow(Wednesday)to review the mitigation plan and I will give him the added fee and pick up the receipt when I pick up the documents, etc. I copied John on this email so he is on the same page. Sincerely, Gretchen Yahn gey@ceicountry.com www.ceicountry.com (540)219-2984(Mobile) Castlerock Enterprises, Inc. From:Todd Shifflett Date:Tuesday,September 22, 2015 at 2:00 PM To:Gretchen Yahn Cc: Danielle Roth, Emily Lantz Subject: Bridlespur Farm -WP0201500072 Good Afternoon, We have received your VSMP application and $1,350.00 fee. On the application you have checked that there is a Mitigation plan. Letter"H" on the application "Mitigation Plan satisfying the requirements of code section 17-406 for any proposed disturbance of stream buffers." This is an extra $150.00 fee per the ordinance. Please submit the check or cash to Community Development. If there is no Mitigation plan review, please let me know so I can remove it and let the engineering reviewer know. Thank You, Todd Shifflett Community Development Engineering Division 1