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Home My WebLink AboutWPO202200047 Correspondence 2023-02-14•see 0 f 608 Preston Avenue P 434.295.5624 Suite 200 F 434.295.1800 T I M M O N S GROUP Charlottesville, VA 22903 www.timmau.com February 13, 2023 Matt Wentland County of Albemarle Community Development 401 McIntire Rd, North Wing Charlottesville, VA 22902-4579 RE: WPO-2022-00047 -Southwood Villages 3 & 4—VSMP Permit Plan Review -Comment Response Letter Dear Mr. Wentland: We have reviewed all of your comments from December 20, 2022, and made the necessary revisions. Please find our responses to the comments below in bold lettering. County Code section 17-410 and Virginia Code §62.1-44.15:34 requires the VSMP authority to act on any VSMP permit by issuing a project approval or denial. This project is denied. The rationale is given in the comments below. The VSMP application content requirements can be found in County Code section 17-401. 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. Provide a completed and signed DEQ registration statement. A signed registration statement is now included in the SWPPP. 2. Provide a signed certification. A signed certification statement is now included in the SWPPP. 3. After approval, update the SWPPP with the stamped plans. Acknowledged. B. Pollution Prevention Plan (PPP) The PPP content requirements can be found in County Code section 17-404. 1. The PPP appears to be acceptable at this time. Acknowledged. ENGINEERING I DESIGN I TECHNOLOGY C. Stormwater Management Plan (SWMP) VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a SWMP. This plan is disapproved, and the reasons are provided in the comments below. The stormwater management plan content requirements can be found in County Code section 17-403. 1. This plan cannot be approved until the 4.73 Ibs/yr of nutrient credits have been purchased. Please contact Ana Kilmer prior to purchasing credits. Since this project drains to impacted streams, the credits will need to be purchased from the Ivy Creek or Rivanna River Credit banks, since they are located in the same HUC8. [9VAC25- 900-91. B]. Acknowledged — upon conditional approval, credit purchase will be coordinated with our client and Ana Kilmer. The credits requested to be purchased have been reduced from 4.73 Ibs/yr to 2.20 Ibs/yr. We were originally modelling bio #4 in Village 4 as level 1 bio in the VRRM, when our calculations and detail are designed as a level 2 basin. This update is the reason behind the reduction in the needed nutrient credit purchase. 2. A Stormwater Maintenance Agreement will be needed. Contact Ana Kilmer to begin this process. Acknowledged — upon conditional approval, we will coordinate with our client to engage with Ana Kilmer for the agreement. 3. Revise grading so runoff is directed away from buildings. The grading slopes towards the buildings in several areas. The grading has been further detailed and areas of the layout have been updated to eliminate the areas that runoff is directed towards the proposed buildings. There are (8) units along Private Alley 4 in Village 4 where a small amount of runoff is directed towards the front of the units. This area has been addressed via a combination of small yard drains for typical drainage and swales for overland relief away from openings. Additional detailed grading will be provided with the siting plans during building permit review. This stick of units has been broken into two sticks for overland flow relief between the units. 4. The grading in the laydown area next to the roundabout channelizes the runoff. Provide ditch designs and quantity control or revise to be sheet flow. This grading is intended to promote sheet flow in the interim Village 5 condition, however the ultimate condition is intended to flow into extended detention #1. As such we have clarified this intent with a drainage diversion to direct this flow into extended detention #1. The intent is also that an additional plan or amendment will be prepared and processed while construction of this plan is underway to also develop this temporary staging/storage area. With that future plan or amendment, the staging/storage area will be relocated to a new area on site for contractor needs. All that to be said we do not intend this grading and temporary diversion to be permanent, but rather a phase in the overall development process. We have noted a commitment to a permanent measure of this conveyance with an amendment if ever needed should an unforeseen circumstance extend construction durations or overall development horizons. 5. Provide more details on the SWM facilities. Include views of the facilities at a larger scale with the various level 1 and level 2 requirements labelled. Also show the planting plans for all the facilities. Detailed facility plan sheets are now included as sheets C6.3 — C6.6 with labels to help review the various BMP requirements. 6. Show the aquatic bench in the wet pond forebay (BMP Spec. 14 sect. 6.4). An aquatic bench has been added to the wet pond forebay, along with aquatic bench planting shown on the detailed landscaping plans. 7. Show the forebays in the ED ponds (BMP Spec. 15 sect. 6.4). A forebay has been added to ED#1, along with a micropool as required. After discussion with Matt W., we do not believe a forebay is necessary for ED #2 as the pretreatment occurs in the forebay of bioretention #4 prior to spilling into the extended detention basin as illustrated in the clearing house specifications. 8. Include the riprap/permanent OP in the drainage easements. Drainage easements have been expanded to include the riprap/permanent OP. 9. Show easements on the swales between pipe outlets and SWM facilities. Easements have been provided over swale between pipe outlets and SWM facility. 10. Provide an exhibit (separate from the plans) that shows the proposed improvements overlaid with the removed stream buffer and the green space from the ZMA. An exhibit is included in this resubmittal with the overlaid stream buffer and green space from the ZMA. *Overall note: We wanted to reduce the embankment heights on ED #1 and wet pond #1, so the elevations of both those basins have decreased, but the footprint has remained similar. In addition, with the embankment height, we felt it more prudent to include emergency spillways on both ponds rather than additional freeboard for additional protection. We have designed the pond to essentially function with a principal spillway with the emergency spillway inactive or only partially activated for the 100 year storm event as additional protection in the event of partial clogging in the principal spillway. D. Erosion and Sediment Control Plan (ESCP) Virginia Code §62.1-44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This plan is disapproved, and the reasons are provided in the comments below. The erosion control plan content requirements can be found in County Code section 17-402. 1. Include a note that additional measures may be required at the request of the County Inspector. The note "Additional measures may be required at the request of the County Inspector" has been added under Erosion and Sediment Control Measures, on sheet C3.0. 2. The CWD must be released through a stabilized outlet. Include other measures along with the CWD or move/extend the CWD (VESCH 3.09). With final tweaking/adjustments of BMPs for the resubmission, the CWD has been removed from this area and therefore no stabilized outlet is included. 3. For diversions over 2% slope, show stabilization per VESCH 3.17 (VESCH 3.09). A note to stabilize all channels with Class 1 riprap (2'-0" depth) has been added to all Phase 1 and Phase 2 E&S sheets. In addition, "See Note 1" has been added to all DD's over 2% in plan view. 4. Show the SSF in the area of ST #1 on sheet C3.13 (the label is showing but not the linework). The perimeter control SSF and SF has been updated to correctly plot between all phases (there were multiple areas this was happening beyond just downstream of ST #1). The VSMP permit application and all plans may be resubmitted for approval when all comments have been satisfactorily addressed. For re -submittals please provide 2 copies of the complete permit package with a completed application form. Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting to discuss this review. Process: After approval, erosion and sediment control and stormwater management improvements must be bonded. The bonding process begins when the plan is approved, and the applicant submits a bond estimate request form and fee to the Department of Community Development. A plan reviewer will prepare estimates and check parcel and easement information based on the approved plans. The County's Management Analyst will prepare bond agreement forms, which will need to be completed by the owner and submitted along with cash, certificates or sureties for the amounts specified. The agreements will need to be approved and signed by the County Attorney and County Engineer. This may take 2-4 weeks to obtain all the correct signatures and forms. Stormwater Management Facilities Maintenance agreements will also need to be completed and recorded. The County's Management Analyst or other staff will prepare the forms and check for ownership and signature information. The completed forms will need to be submitted to the County, who will record the agreement. After bonding and agreements are complete, county staff enters project information in a DEQ database for state application processing, if a DEQ permit is required. DEQ reviews the application information based on local VSMP authority approval. At this time, the DEQ portion of the application fees will need to be paid directly to the state. For fastest processing, this is done electronically with the emails provided on the application. DEQ should notify applicants with instructions on how to pay fees. When DEQ approves the application, they will issue a permit coverage letter, which must be posted at the construction site. After DEQ coverage is issued, via the coverage letter, the County can hold a pre -construction conference. Applicants must complete the request for a pre -construction conference form and pay the remainder of the application fee. The form identifies the contractor and responsible land disturber, and the fee remaining to be paid. This will be checked by county staff, and upon approval, a pre -construction conference will be scheduled with the County inspector. At the preconstruction conference, should everything proceed satisfactorily, a joint VSMP and grading permit will be issued by the County so that work may begin. We have included PDF copies of the plans and calculations for your review. If you have any questions or comments, please feel free to give me a call at 434.295.5624 or email bryan.cichocki@timmons.com. Sincerely, Bryan Cichocki, PE Project Manager