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Home My WebLink AboutWPO201800040 Other 2018-07-18COLLINS 200 GARRETT ST, SUITE K CHARLOTTESVILLE VA 22902 434.293.3719 PH 434.293.2813 FX www.collins-engineering.com TRANSMITTAL ❑ FAX ❑ MAIL X DELIVERY TO: JOHN ANDERSON, PE FROM: GRAHAM MURRAY, PE COMPANY: DATE: 7/18/18 FAX: TOTAL NO. OF PAGES INCLUDING COVER: PHONE NUMBER: SENDER'S PHONE NUMBER: PROJECT/SUBJECT: Flow Auto VSMP Plan (WPO 2018000040) PLEASE FIND ENCLOSED: NO. COPIES DATE DESCRIPTION 4 7/18/18 PLANS 1 7/18/18 COMMENT RESPONSE LETTER 1 7/18/18 REVISED VRRM CALCS FOR REPLACEMENT / INSERTION INTO PREVIOUSLY SUBMITTED & REVIEWED CALCULATIONS PACKET NOTES/ COMMENTS: THE APPLICANT ATTEMPTED TO FULLY ADDRESS ALL REMAINING VSMP PLAN COMMENTS RELATED TO THE CONSTRUCTION PLANS THEMSELVES. THE APPLICANT KINDLY REQUESTS HE BE CONTACTED PRIOR TO ISSUANCES OF A CONDITIONAL APPROVAL OR COMMENTS TO TROUBLE SHOOT MINOR ITEMS SHOULD IT BE NECESSARY. SINCERELY, GRAHAM MURRAY GRAHAM@COLLINS-ENGINEERI NG. COM (434) 566-3011 RECEIVED BY: SIGNATURE DATE Mr. John Anderson, PE Albemarle County Community Development Engineering Department 401 McIntire Road Charlottesville, VA 22902 RE., Flow Auto VSMP Amendment (WPO 2018000040) Dear Mr. Anderson Thank you for the comments dated June 28, 2018 on our VSMP plan submission of Flow Auto. Below is our comment response letter for the comments. A. Stormwater Pollution Prevention Plan (SWPPP) 1. The operator has provided his email and may be contacted via email. 2. The applicant is in the process of obtaining the registration statement's signature, with its date. Once it is received it will be provided to County Engineering. 3. The updated ESC plans, SWM plans and SWPPP exhibit have been included in the report. 4. Similar to the response above to #2, the applicant is currently working on obtaining the signed/dated certification statement. Once it is received it will be provided to County Engineering. Stormwater Management Plan 1. The summary tab from the VRRM, version 3.0, redevelopment spreadsheet has been transferred to sheet 8. Also, in a phone conversation between Mr. Anderson and Mr. Murray on July 16th the VRRM calculations were discussed. In this conversation it was determined the applicant could utilize the existing Filterra inlets to remain for water quality credit since they are located within the amendment's parcel area and were part of the original plan. However current removal standards of 50% are utilized instead of the originally approved 65% removal rates. The result was a slight increase in the minimum nutrient credits required to be purchased. The VRRM spreadsheet requirements increased from 0.78 Ibs/yr to 1.00 Ibs/yr. The plans have been updated accordingly, and revised VRRM spreadsheet printouts have been included with this submission to replace the previously submitted and reviewed sheets in the April 19, 2018 calculations packet. Due to the minimal comments and required revisions, the attached VRRM calculations are the only sheets that need updating. 2. The cover sheet has been revised to reference WPO 200800020. The applicant also acknowledges a VA DEQ general construction permit is not required with this plan. 3. This comment is acknowledged. 4. Sheet 7 has been revised in the 'Stormwater Management Plan Details' to label the drainage pipes and structures. 5. Sheet 7 has been revised in the 'Stormwater Management Plan Details' to include a 2nd arrow pointing to the 2nd access manhole with steps (near the inlet). 6. A. Sheet 7's 66" weir plate detail has been revised to state the 4.90' dimension is for the top of the weir plate's width. Also, the weir plate's base elevation was corrected to now read 395.00'. B. Sheet 7 has been revised in the 'Stormwater Management Plan Details' to correctly label the overflow bypass pipe length and slope. C. Structure EX 1's rim elevation was confirmed. A survey was completed and its rim elevation is correct. 7. The applicant consulted with the manufacturer. Unfortunately, because the contractor has not been selected for this project and its construction equipment is therefore unknown, the manufacturer can only list a variety of minimum covers to account for the loadings. These minimum covers are dependent upon the type of construction vehicle(s) used and are shown on sheet 9. The applicant hopes County Engineering understands this requirement. Also, the manufacturer has listed their company's requirements for their pipes' bedding and foundation. These can be viewed on sheet 10 and are consistent with the company's minimum standards. And lastly. the applicant has requested the manufacturer provide an estimate for the construction costs associated with the underground detention system. Once the applicant receives feedback, it will be provided to County Engineering. 8. Sheet 8 has been revised to include site -specific profiles of the 66" underground detention system. The corresponding alignments, stations and nomenclature are shown on the previous sheet 7 with a note directing the reviewer and contractor to sheet 8. 9. The plans originally provided the contractor the option to install the round, or square, perimeter for the access manholes. At the reviewer's request, the plans have been revised to specify the round perimeter. The manufacturer updated the plans' detail and all 9 notes accordingly on sheet 9 (bottom -center). 10. A.The geomembrane barrier is shown on sheet 9 in the bottom -left corner in the typical section view detail. The geomembrane barrier is also shown on sheet 10 in the top -left under the header 'Geomembra ne Barrier. In addition to this, the geomembrane barrier is shown and labeled on the three site -specific profiles depicted on sheet 8 in the upper -left corner (UGD Row No. 1, No. 2 and No. 3). The manufacturer advised the applicant the 20 mil PE impermeable liner is to be placed directly over the top of the underground detention pipes. B. Please see the opening 4 sentences to the response above to comment V. C. The applicant appreciates this comment. The applicant consulted with the manufacturer. The applicant was advised that the inspection requirements listed on sheet 10, in the middle -right side of the page, are consistent with the company's standards and have been found to be sufficient. The applicant hopes this comment can be considered resolved, along with comments #7, 9 and 10 as they relate to the manufacturer's specifications. D.The 'Inspection' section on sheet 10, in the middle -right side of the page, has been revised to require quarterly inspections. This is above and beyond typical manufacturer requirements. B. Pollution Prevention Plan (PPP) 1. A pollution prevention plan has been included in the SWPPP report. C. Erosion and Sediment Control Plan (ESCP) Sheet 3 1. A modified temporary 18" diversion detail, for use on paved surfaces, has been provided on sheet 3 in the lower - middle section of the sheet. This detail mandates the contractor install an asphalt berm, or a stone berm with an impermeable fabric cover on the clean water (upland) side. This diversion, along with the unmodified diversion for use over soils, are labeled types A and B. The ESC plan sheets were updated accordingly to reference type A or B diversions. This will eliminate confusion and mandate the contractor install the impervious diversions over paved surfaces. This newly added 'modified' diversion is applicable to the temporary diversion berms and the temporary right-of-way diversions. Sheets 4, 5 & 6 2. Please see the response above to the ESC comment #1. 3. Sheets 4-6 have been revised to mandate the stored fuel and fueling equipment be placed in a container that has a volume sufficient to hold the stored fuel, plus an additional 6" overhead to account for the 24 hour, 10-year rainfall event. 4. The construction entrance note has been revised to read 12'x70' and to specify a wash rack. The note has also been revised to state no material may be tracked from this site onto US route 250. 5. Drainage pipes and structures are now labeled on sheets 4-6. 6. The previously submitted and reviewed Final Site Plan sheet #5 has been added to this plan. This duplicate sheet includes the drainage computations for the inlets and pipes. 7. The applicant appreciates this comment. This is a small site, so there are various limiting factors. The plans were revised however to increase the area by 184%. 8. The SAF label has been added to the plans on sheets 3 and 5. The floor dimensions and weirs are also labeled on these sheets. 9. Please see the response above to the ESC comment #1. 10. This note has been added to sheet 6, directly west/below the proposed underground detention system. Please let me know if you have any questions or require any additional information for final VSMP approval. The applicant understands there are multiple comments in this letter, however given the lack of difficulty and objection to the plans the applicant is hopefully for an approval with this resubmission and is available to trouble shoot items as needed. Sincerely, Graham Murray, PE graham@collins-engineering.com