Loading...
HomeMy WebLinkAboutWPO201400075 Correspondence 2014-10-21 "war '"✓' PROJECT MANAGEMENT SHIMP CIVIL ENGINEERING LAND PLANNING ENGINEERING October 21, 2014 Mr. John Anderson Civil Engineer City of Charlottesville Department of Community Development Regarding: Rocky Hollow- Erosion Plan Dear Mr. Anderson, Thank you for your review of the erosion control plan for Rocky Hollow. We have revised the plans per engineering review comments dated October 1, 2014. Please find below detailed comment responses letter describing the changes we have made to address each of your comments. Engineering 1. The project description has been expanded to include driveway length, critical slope and stream buffer disturbance. No alternative driveway options were considered. 2. Construction sequence has been updated to include stream pumping provisions. 3. We understand that the owner has no intention of changing existing logging road other than installing base stone and asphalt for the driveway. The max. slope of the logging road is 13.5%. 4. Stockpile locations have been assigned and labeled on sheets C3 and C4. 5. The staging area has been identified and labeled on sheets C3 and C4. 6. The mitigation area has been identified and labeled within the limits of disturbance and stream buffer. 7. Critical slopes are now being shown with a light hatch on sheet C4. 8. The outlet protection dimensions have been calculated and labeled per standards in Virginia Erosion and Sediment Control Handbook. 9. A driveway culvert has been furnished to divert flow to BMP with a ditch. 10. Silt fence has been furnished around the box culvert and new sediment trap to limit sediment deposition into the stream. 11. The plan has been corrected to show the stream buffer more clearly. 12. The plan has been corrected to show the tree line. 13. Wing wall skew angles have been depicted and furnished. 14. Based on channel conditions and the Drainage Manual, we believe that an apron is not necessary. 15. Brick symbol is representative of a storm water conveyance channel and has been indicated in the legend on sheet C4. 16. We recommend English ivy for ground cover for the areas with a slope greater than 3:1, see sheet C4. 17. Wing walls have been furnished with stabilization matting, specifically class 1 riprap to prevent erosion. 18. Box culvert dimensions have been labeled and pre cast system indicated, see sheet C4 and C5 culvert profile. 19. Driveway materials and dimensions have been provided on sheet C5. 20. OHW has been labeled on culvert profile at 4"above existing stream bed, sheet C5. Culvert profile inverts have been updated with a 10 year storm provided as well, based on the VDOT headwater depth nomograph. 21. The required opening for the box culvert to account for countersinking is 5.5"x 8"and these dimensions are used for the purpose of hydraulic calculations. The next larger size 6'x8' has been recommended. 22. Foundation notes have been added to sheet C5. Based on standard assumptions for native soil in the area, it should be able to withstand the weights of the box culvert and driveway. If you have any questions please feel free to contact me via e-mail at Morgan(c.shimp-engineering.com or Justin Shimp at Justin aAshimp-enqineerinq.com or by telephone at 434-953-6116 Sincerely, (/(11Pg Morgan Bell Page 2 PROJECT MANAGEMENT SHIMP CIVIL ENGINEERING LAND PLANNING ENGINEERING November 10, 2014 Mr. John Anderson Civil Engineer Albemarle County Department of Community Development Regarding: Rocky Hollow- Erosion Plan Dear Mr. Anderson, Thank you for your review and detailed explanation of your comments of the erosion control and mitigation plan for Rocky Hollow. We have revised the plans per engineering review comments dated November 4, 2014. Please find below detailed comment responses describing the changes we have made to address each of your comments. Engineering A. Stormwater Pollution Prevention Plan 1. The SWPPP has been properly filled out and is consistent with VDPES Registration Statement, including required signatures. 2. The area of disturbance listed on the plans is consistent with the General VDPES Registration Statement. (1.91 ac) B. VSMP: SWPPP: Stormwater Management Plan 1. Thank you for your assistance in determining a suitable plan for stormwater measures. Currently, the 88 acre site has 4.15 acres of forested area within the stream buffer. This area is already recognized by Albemarle County as conserved. After much review, we decided to use this forested area for Runoff Reduction purposes thus not requiring a conservation easement. This will meet the requirement for water quality compliance on the Runoff Reduction spreadsheet. We will provide an updated version of the spreadsheet via email/ 2. The permanent conservation easement is within stream buffer, because Albemarle County recognizes the stream buffer area as conserved. See sheet C2 on Mitigation Plan. 3. SWM narrative has been furnished according to your requests. 4. Comment has been noted, the registration statement is attached. C. VSMP: SWPPP Erosion Control Plan 1. The project description has been expanded to include driveway length, critical slope and stream buffer disturbance. No alternative driveway options were considered.Addressed. 2. Construction sequence has been updated to include stream pumping provisions. Addressed. 3. We understand that the owner has no intention of changing existing logging road other than installing base stone and asphalt for the driveway. The max. slope of the logging road is 13.5%.Addressed. 4. Stockpile locations have been assigned and labeled on sheets C3 and C4. Addressed. 5. The staging area has been identified and labeled on sheets C3 and C4. Addressed. 6. The mitigation area has been identified and labeled within the limits of disturbance and stream buffer. Follow-up:An area down stream (within the buffer area)from the property has been identified as unforested and thus suitable for a second mitigation area of.37 acres. We have labeled the area with the required number of specified trees. If more detail is required, please let us know. 7. Critical slopes are now being shown with a light hatch on sheet C4. Follow-up:The steep slope hatch has been made darker and is now visible on all sheets. 8. The outlet protection dimensions have been calculated and labeled per standards in Virginia Erosion and Sediment Control Handbook. Addressed. 9. A driveway culvert has been furnished to divert flow to BMP with a ditch. Addressed. 10. Silt fence has been furnished around the box culvert and new sediment trap to limit sediment deposition into the stream. Addressed. 11. The plan has been corrected to show the stream buffer more clearly. Follow up:The stream buffer has been made bolder and visible on all sheets. 12. The plan has been corrected to show the tree line. Follow-up:Our apologies for the printing error, the tree line is now visible. 13. Wing wall skew angles have been depicted and furnished. Addressed. 14. Based on channel conditions and the Drainage Manual, we believe that an apron is not necessary. Addressed. 15. Brick symbol is representative of a storm water conveyance channel and has been indicated in the legend on sheet 04. Addressed. 16. We recommend English ivy for ground cover for the areas with a slope greater than 3:1, see sheet C4, Addressed. 17. Wing walls have been furnished with stabilization matting, specifically class 1 riprap to prevent erosion.Addressed. 18. Box culvert dimensions have been labeled and pre cast system indicated, see sheet C4 and C5 culvert profile. Follow-up:Wall,ceiling and floor thicknesses have been added to culvert profile, taken from VDOT BCS-05 Single Box Culverts. VDOT standard details on box culverts have been added to sheet C6 of the ECSP. 19. Driveway materials and dimensions have been provided on sheet C5. Addressed. 20. OHW has been labeled on culvert profile at 4" above existing stream bed, sheet C5. Culvert profile inverts have been updated with a 10 year storm provided as well, based on the VDOT headwater depth nomograph. Follow-up: 10 year storm line has been converted from a line to an elevation located at the culvert invert. Determined by headwater depth ratio of 1.3 x box culvert depth of 6'= 7.8' above culvert invert. 21. The required opening for the box culvert to account for countersinking is 5.5" x 8" and these dimensions are used for the purpose of hydraulic calculations. The next larger size 6'x8' has been recommended. Addressed. Page 12 22. Foundation notes have been added to sheet C5. Based on standard assumptions for native soil in the area, it should be able to withstand the weights of the box culvert and driveway. Addressed. 23. The construction entrance has been adjusted to not pass the stream. D. VSMP:Mitigation Plan 1. The inconsistency of stream buffer disturbance areas have been addressed and updated to 16,600 SF. This was due to disparities between the GIS and topo files. 2. Replanting area has been updated and depicted on mitigation plan sheet C2. If you have any questions please feel free to contact me via e-mail at Morgan anshimp-engineerinq.com or Justin Shimp at Justin(a,shimp-enqineering.com or by telephone at 434-953-6116 Sincerely, jo/o Morgan Bell • Page 13 ,....., ‘,...... PROJECT MANAGEMENT SHIMP CIVIL ENGINEERING LAND PLANNING ENGINEERING C� October 21st, 2014 Mr. John Anderson Civil Engineer County of Albemarle Department of Community Development Regarding: Rocky Hollow- Erosion Plan Dear Mr. Anderson, Please find attached with this letter 2 sets of the corrected Erosion Control Plan with a comment response letter and Stormwater&Mitigation Plan. Also enclosed is the SWPPP, VSMP application with payment and the RRM has been electronically submitted. If you have any questions please feel free to contact me via e-mail at Morgan@shimp-engineering.com or Justin Shimp at Justin@a,shimp-engineering.com or by telephone at 434-953-6116 Sincerely, e/Yc751- Morgan Bell ,s.... .4.. PROJECT MANAGEMENT SHIMP CIVIL ENGINEERING LAND PLANNING ENGINEERING November 20, 2014 Mr. John Anderson Civil Engineer Albemarle County Department of Community Development Regarding: Rocky Hollow- Erosion Plan Dear Mr. Anderson, Thank you for your all of your help with the Mitigation and E&S plans for the Rocky Hollow site. I have taken into account your suggestions and implemented them on the plan. I have added the necessary level spreaders with a minimum timber length of 12' along with a note for the contractor to verify that they are constructed parallel with the contour lines. If you have any questions please feel free to contact me via e-mail at Morgan(a shimp-enqineering.com or Justin Shimp at Justin@a,shimp-enqineerinq.com or by telephone at 434-953-6116 Sincerely, th0-1 ' Morgan Bell