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HomeMy WebLinkAboutWPO201400074 Correspondence 2014-10-31 SH' IMP PROJECT MANAGEMENT CIVIL ENGINEERING LAND PLANNING ENGINEERING October 31, 2014 Mr. Max Greene Albemarle County Department of Community Development Regarding: WPO 2014-0074- Riverside Village Erosion and Sediment Control Plan Dear Mr. Greene, In response to your review comments delivered via e-mail on October 22, 2014 we have provided the additional information that you requested and have updated the plans as follows: 1. We have attached a copy of the DEQ coverage letter, with coverage starting June 26, 2014. 3. Additional BMP details are provided in the calculation packet and C17. 4. Profiles have been added demonstrating that the bottom portion of the infiltration system is above existing grade. 5. Forebays have been added to the biofilters. 7. The road profile is included with this submittal, showing that inlets B2 and B3 are in a sump. 8. LD-204 is now provided, with computations demonstrating capture of the 10-year storm. C. 2. Stormwater profiles are included in this submittal. 3. Pipe updated per VDOT requirements. 4. Narrative updated to correctly reference C3. 5. Sheet numbers updated to include prefix"C". 6. Benchmarks are now shown on C3 and C24. 7. Reference added to C21, Erosion and Sediment Control Narrative. 8. Outlet protection has been extended to cover full area of stream disturbance. If you have any questions please do not hesitate to contact me at your earliest opportunity. I may be reached at: Justin(a shimp-engineerinq.com or by phone at 434-953-6116. Best Regards, Justin Shimp, P.E. Shimp Engineering, P.C. 'Nose Nee SHIMP PROJECT MANAGEMENT CIVIL ENGINEERING LAND PLANNING ENGINEERING September 30th, 2014 Mr. Max Greene Albemarle County Department of Community Development Regarding: WPO 2014-0074- Riverside Village Erosion and Sediment Control Plan Dear Mr. Greene, In response to your review comments delivered via e-mail on September 23, 2014 we have provided the additional information that you requested and have updated the plans as follows: D.1. We have paid the fee to the State for the 2014 Permit and provided copies of the registration statement and check to Community Development Intake Staff. We expect to receive copies of the permit at any time and will forward the permit letter to you immediately upon receipt. E.1. As noted in our response to Mr. Brooks, this project has received VSMP permit coverage under the 2009 SWM regulations and the use of the VRRM is not required. We have provided copies of the Appendix 5D worksheets from the 1999 handbook to demonstrate compliance with the applicable water quality requirements. F.1. Our site is currently approved and permitted with a stone construction entrance, based on our conversation at the pre-construction meeting we are under the impression that the construction entrance as built may stay in place provided that the contractor is keeping mud and dirt off of route 20. Please advise If this is no longer the case. The narrative section has been updated to reflect this requirement. F.2. The narrative has been updated to reflect the current site conditions based upon the grading that has taken place to date. F.3 Per our discussion last week we understand that the topographic data as shown on the plan may continue to be used for this submission. I have reviewed the site grading against the approved erosion control plan for the sediment basins and have found that the contractor has generally honored the drainage divides from that plan. It appears that the largest area planned to drain to the sediment basin closest to the river is consistent with the design for that basin. F.4. The erosion control measures for the widening of Route 20 south of the entrance have been improved to provide increased protection. Two sediment traps have been added. The ditch from the sediment basin has been shifted slightly to make space for a sediment trap and diversion along the toe of the fill slope. We envision a temporary diversion between the permanent ditch and toe of the slope to divert runoff from the fill slope into ST-2 until the slope is full stabilized.At that time the trap and diversion may be removed and runoff from the slope can drain to the permanent ditch. r Ylr►• •�v G.1. The landscape plan will be updated with the appropriate plantings as required. This plan will be submitted to you directly by October 3rd, 2014 for review. If you have any questions please do not hesitate to contact me at your earliest opportunity. I may be reached at: Justint shimp-enqineerinq.com or by phone at 434-953-6116. Best ".t ustin Shimp, P.E. Shimp Engineering, P.C. Noir SHIMP PROJECT MANAGEMENT CIVIL ENGINEERING LAND PLANNING ENGINEERING September 30th, 2014 Mr. Glenn Brooks, P.E. County Engineer Albemarle County Regarding: WPO 2014-0074- Riverside Village Stormwater Management Plan Dear Mr. Brooks, In response to your review comments delivered via e-mail on September 22, 2014 we provided the additional information that you requested and have updated the plans as follows: 1. This project is eligible for review under type IIC technical criteria. A copy of the 2009 State General Permit is attached for your records. 2. Infiltration test were performed for the area of BMP D prior to land disturbing activities, the depth from existing grade in the sediment basin to the bottom of the infiltration trench is approximately 4'. This area will be excavated to the grade tested for infiltration and the underground system will be installed in that location. A signed and sealed report prepared by Froehling and Robertson, Inc. is attached certifying results for BMP west(or D in our plans) 3. A new 1"=10' plan detail for the underground detention system has been provided with all of the requested details.A profile has been added to the plans showing the relationship between existing grade and the proposed grade for the infiltration system. 4. The proposed infiltration system is not in a fill area, It will be cut into existing grade by approximately 4'. Please refer to the profile on the plans for details. 5. Each BMP is now shown with a fore bay for removal of sediment/etc. The bio-filters have small stone weirs to provide a settling area within the bio-filter and the underground infiltration unit has been adjusted to include an isolated row for the intake runoff that provides a fabric liner along the lower half of the pipe to permit a ponding of 2.5' of depth within the first pipe before runoff will overtop the first weir wall and begin filling the rest of the system.Access ports have been provided at each end of the system to allow access for inspection and cleaning out of the underground storm water management system. 6. Complete water quality sizing information has been provided for the surface area of the Bio-Filters and the water quality storage volume of the infiltration system. 7. Please refer to the road plans for information on the road drainage system. A sump has been designed for the entrance to capture runoff into the bio-filter. 8. Drainage calculations have been updated to a 7.0 inch/hour storm to achieve greater or equal capture for the 10 year storm. Nave r✓ For your convenience, we have added tabs to the storm water report outlining each section. Sticky notes have been placed on the pages with notes where you may find the additional information requested in your comments. If you have any questions please do not hesitate to contact me at your earliest opportunity. I may be reached at: Justin a(�.shimp-engineerinq.com or by phone at 434-953-6116. Best Regards, ■stin Shimp, P.E. Shimp Engineering, P.C.