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Home My WebLink AboutWPO201300079 Correspondence 2014-05-20 N# ' Jt CA- 0,, 2St BOHLER ENGINEERING 0a' 28 Blackwell Park Lane,Suite 201,Warrenton,VA 20186 Professional Engineering Services Telephone:(540)349-4500 Fax: (540)349-0321 LETTER OF TRANSMITTAL VIA: Hand Delivery TO: Albemarle County RE: WPO Plan—E&S Phase II&SWM 401 McIntire Road 1st Submission Charlottesville,VA 22902 5th Street Station 5th Street SW&Avon Street Ext. (434)296-5832 Charlottesville,VA 22902 Albemarle County ATTN: Glenn Brooks DATE: May 20, 2014 JOB NO: V122001 WE ARE SENDING YOU ❑Shop drawings ❑Copy of letter Attached ❑ Prints ❑Change order COPIES JOB# DATE REVISION REVISION SHEET NO. DESCRIPTION DATE 1 V122001 5/20/14 Check# Check in the amount of$300.00 made payable to Albemarle County 1 V122001 5/20/14 1-2 of 2 Comment Response Letter 1 V122001 5/20/14 Stormwater Management Report 2 V122001 12/13/13 1 5/15/14 1-46 of 46 Water Protection Plan E&S Phase II&SWM These Are Transmitted: ®For approval OFor your use ['As requested ❑For review and comment DApproved as submitted ['Approved as noted ❑Returned for corrections REMARKS: Please find enclosed the Water Protection Plan(E&S Phase II& SWM)and corresponding documents for the above mentioned project in Charlottesville,VA. If you have any questions or require additional information, please do not hesitate to contact this office at (540) 349-4500. COPY TO: SIGN !. of 7 — — ie R. Hines,P.E. File „wawa Blackwell Park Lane, Suite 201 Warrenton, VA 20186 BOI-rLER PHONE 540.349.4500 ENGINEERING FAX 540.349.0321 May 20, 2014 Via Hand Delivery County of Albemarle Department of Community Development 401 McIntire Road,North Wing Charlottesville, VA 22902-4596 Attn: Glenn Brooks Re: WPO Phase II &E&S Plan WPO2013-00079 5th Street Station 5th Street SW&Avon Street Ext. Charlottesville,VA 22902 Albemarle County BE#V122001 Dear Mr. Brooks: Bohler Engineering is pleased to submit on behalf of S.J. Collins,the revised Water Protection Ordinance Plan for 5th Street Station in Charlottesville, VA. The following is our comment response letter addressing comments received from you dated January 15, 2014. Each comment is addressed and responded to as follows: Erosion& Sediment Control: Comment 1: Adequate limits and perimeter measures out of work areas (stream areas must be protected below walls. Not clear how this happens.) Response 1: Perimeter protection has been provided below the walls and around the limits of clearing and grading. Sediment basins and traps have been placed such that the wall construction can take place while the traps and basins collect the drainage before reaching the wall areas and discharge the runoff beyond the walls. Comment 2: All stages protected adequately(SF not adequate as a sole protection). Response 2: Adequate protection has been provided for the phases. A separate WPO plan has been submitted for the site disturbance. This plan identifies the final phase of control as the site is being stabilized. Comment 3: Adequate channels (not found in plan package) - This plan shows only limits and fence. There do not appear to be any sediment trapping measures shown. - There is not enough protection for Moores Creek and the wall construction. - Does not match swm plans. OTHER OFFICE LOCATIONS: •Southborough, MA •Albany, NY • Purchase, NY • Ronkonkoma, NY •Warren, NJ •Center Valley, PA 508.480.9900 518.438.9900 914.251.9800 631.738.1200 908.668.8300 610.709.9971 •Chalfont, PA •Towson, MD •Sterling, VA • Bowie, MD • Fort Lauderdale, FL 215.996.9100 410.821.7900 703.709.9500 301.809.4500 954.202.7000 CIVIL AND CONSULTING ENGINEERS • SURVEYORS • PROJECT MANAGERS • ENVIRONMENTAL CONSULTANTS • LANDSCAPE ARCHITECTS www.BohlerEngineering.com rill BOH LER '6-' `` ENGINEERING Glenn Brooks 5th Street Station WPO Phase II&E&S 5/20/14 Page 2 of 3 Response 3: Moore's Creek is an adequate channel - A separate WPO plan has been submitted for the E&S Phase 1 site disturbance. This plan identifies the E&S Phase 2 as the site is being stabilized and the overall site construction efforts have been completed. For the stabilized site; individual inlet protection, perimeter silt fencing, outlet protection; and final seeding measures are adequate. - The site clearing and grading are proposed with a separate WPO plan. This plan shows the final stabilization and SWM features. The wall construction will be protected by several sediment basins and traps that have been placed such that the wall construction can take place while the traps and basins collect the drainage before reaching the wall areas and discharge the runoff beyond the walls. The County directed us to submit this as a separate plan for file keeping purposes. - The SWM design has been updated in this plan. Stormwater Management: Comment 1: Enough detention storage for on-site areas. Response 1: Adequate detention storage has been provided. Comment 2: Sealed hydrologic and hydraulic computations provided - System A+ B areas should assume forested conditions prior to development. The previous clearing was an unfinished project. - All facilities, incl. level spreader, need maintenance access. - These are non-standard sand filters. Use state approved standards, or provided DEQ approval for these systems at the desired removal efficiency. Demonstrate WQV is captured in filters. Demonstrate extended detention will not inundate filters. There is currently no way to replace for rust, or easily inspect or clean, or replace media. Design for theses and provide structural certifications. - The in-stream flow splitter is a clogging problem and the pond may be below the water table. I just don't see this as approvable at all. Per the zoning, build a in-line pond upstream of the culvert and pay the Army Corps fees necessary for disturbance, or request a variance/ZMA. - Provide DEQ approval for the landfill pond. - Provide scaled sections and profiles through facilities. Manufacturer's generic drawings are not adequate. - The plans are too big for storage in county files. Please separate all the computations into a sealed package. Clarify all storage volumes used and assumptions and sizing, and outlet structures, after revised hydrology per above. There were not enough plan detail to verify computations for structures. Response 2: A separate SWM Report has been provided and sealed for review and approval. - The three (3) vault systems have been designed assuming a good wooded condition. Please refer to the Pre-Development computations within the SWM Report. - The Flow Splitter has been removed. The level spreaders are intended to act more like rip-rap stilling basins that allow the runoff to dissipate into the wetland areas that they are adjacent to. CIVIL AND CONSULTING ENGINEERS • PROJECT MANAGERS • SURVEYORS • ENVIRONMENTAL CONSULTANTS • LANDSCAPE ARCHITECTS 21 B O H L E R Glenn Brooks E N G I N E E R I N G 5"'Street Station WPO Phase II&E&S 5/20/14 Page 3 of 3 - These sandfilters have been designed as Washington D.C. Underground Vault Sandfilters in accordance with the VA Stormwater Management Handbook standard 3.12A. Tables have been provided in the SWM Report showing that the WQV is captured in the sandfilter areas. These filters have been designed to capture the first flow and completely fill up before spilling into the vault area. The extended detention is secondary and will be used after the runoff has filtered through the sandfilter or in the event that the sandfilter is full,the extended detention will capture the overflow volume. The depth of the filters and vault has been reduced to provide better maintenance opportunities. Also, the size of the vaults is such that accessibility within the vaults is good for maintenance purposes. - The in-stream flow splitter has been removed as well as the BMP pond adjacent to Moore's Creek. An alternate facility and location are being evaluated. - Approval from DEQ for the landfill pond will be obtained. - Scaled sections of the vaults have been provided. See sheets 14A, 15A,and 16A. - A separate report has been provided with the computations removed from the plan set. Additional information has been provided in the report as requested. Mitigation: Comment 1: Buffers and disturbed areas adequately shown. Response 1: A buffer mitigation plan has been submitted for review and approval. Comment 2: Adequate plantings at 2:1,or other mitigation provided. - A mitigation plan is required for all buffer disturbances. A plan has not been received. Response 2: A buffer mitigation plan has been submitted for review and approval. Should you have any questions regarding this project or require additional information, please do not hesitate to contact me at(540)349-4500. Sincerely, Bohl ngineerin Daniel R. Hines, P.E. cc: Dan Tucker,S.J.Collins DRH/lb H:\12\V122001\Permitting\urisdictional Letters\County WPO Phase II&E&S 1st Review\140520 WPO Phase II&E&S 1st Review CRL.doc CIVIL AND CONSULTING ENGINEERS • PROJECT MANAGERS • SURVEYORS • ENVIRONMENTAL CONSULTANTS • LANDSCAPE ARCHITECTS