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Home My WebLink About20140770 Ver 1_More Info Letter_20150327NCDENR North Carolina Department of Environment and Natural Resources Pat McCrory Donald R. van der Vaart Governor Secretary March 27, 2015 DWR # 14 -0770 Haywood County Adam King Harley Enterprises, LLC 1249 Hendersonville Road Asheville, NC 28803 Subject: REQUEST FOR ADDITIONAL INFORMATION Beaverdam Road Dear Mr. King: On July 23, 2014, the Division of Water Resources (Division) received your application dated June 28, 2014, requesting a 401 Water Quality Certification from the Division for the subject project. The Division has determined that your application is incomplete and therefore cannot be processed. A response to this additional information request is to be received by the Division no later than May 1, 2015. We have reviewed the additional information received on February 10, 2015 but several key elements in the engineering drawings and "Low Density Supplement" sheet remain either missing or unclear which have prevented us from being able to complete the review. We decided to notify you now so that you can make the changes necessary for us to continue our review and expedite the approval of the project. The project review will be placed on hold until these issues are clarified. Topics and items needing additional clarification or correction include the following: 1. It is not clear why the most - recent (February 101h) submittal is proposed for "low- density" and includes the dry pond, level spreader and vegetated filter stormwater control devices on the western edge of the property. These - devices achieve an increased level of treatment but are not required for low density. The information we received from your engineer doesn't explain why these additional control measures were included in the drawings. Were these measures included with the intent of using them later for a high density development in a different phase of the project? If that is the case, we will accept that explanation but the project application will need to be revised and shifted back to the high density review. We can't provide a low density approval and a high Division of Water Resources - Asheville Regional Office 2090 U.S. Highway 70, Swannanoa, North Carolina28778 Phone: 828 - 296 -45001 FAX: 828 - 299 -7043 Internet: www.ncwaterquality.org An Equal Opportunity 1 Affirmative Action Employer— Made in part by recycled paper Adam King DWR# 14 -0770 Request for Additional Information Page 2 of 5 density approval for the same drainage area. Please resubmit accounting for the planned built - out conditions for the site. 2. There remain issues with discernment of the drainage areas and other important plan criteria. a. There are six drainage area labels on the Culvert Permit Plan drawing. We cannot identify any of the boundary areas on the drawing. We noted in our September 2, 2014 memo that "Mr. DeVane specifically asked that all drainage areas on the site be marked so as to be readily observed." This issue was again communicated to Ms. Austin in Mr. DeVane's email on October 14, 2014 when he stated that he "wanted to be able to look at the drawing and see easily discernable drainage and sub - drainage areas ". He also stated in his email to Ms. Austin on December 16, 2014 that "The important part is showing the boundary of each drainage area in the portions of the project that are requested to be permitted as low density." Please make sure that this issue is addressed. b. We understand that the drainage area used to calculate the impervious percentage is 1,166,536 sf. However, we do not see where that drainage area is on the drawing and have no way to check the impervious percentages. Without this information, we can't check flow calculations or sizing of the management practices. As we stated in our September 2, 2014 letter, we cannot determine from the drawings where the delineation between Phase 1 and Phase 2 is planned. Ms. Austin's September 13th description indicates that it is divided by "the existing access driveway and permitted culvert location." As suggested, we've looked at the "Driveway Permit" drawing but that doesn't help us answer the fundamental question of where is the drainage delineation between Phase I and Phase II. We think it runs from south to north to the top of the property but the explanation that a line from the "existing access driveway to the permitted culvert" doesn't tell us what happens on the upper part of the project. There appear to be many culverts: which one is the permitted one? Please indicate on the drawing where that line separating the two phases is located. d. We see from the Legend that an evenly- spaced dashed line represents the property line. However, there are many places where that symbol is used but does not coincide with a property boundary. For example, the Beaverdam road across the southern side of the project seems to have dashed lines on both sides. On the northern side of the project, it seems that part of the 22' X 150' swale is outside of the project's property line. 3. There are many inconsistent numbers regarding the basic requirements of project area size and proposed project density. Without consistency of these basic numbers, we cannot complete our review. a. Page 2 of your Supplement submittal indicates that the proposed built -upon area (BUA) for the project is 43,287 sf. That would be. only 3.7% of the entire project area. That is a very low percentage to preserve as a low density development. Although we cannot determine from the drawing what area the 1,166,536 sf drainage area covers, we can Adam King DWR# 14 -0770 Request for Additional Information Page 3 of 5 see that the percent impervious area of the drawing is much greater than 3.7 %. We see a symbol for "drainage area" in the legend but we don't see that it is used on the site drawing. If you intend to keep the project at low density, your drawing must clearly show the entire drainage area. b. There are only three "swale" drainage areas shown on Table 1 of the Low Density Supplement. They only cover about 300,000 sf. Please clearly account for the remaining 850,000+ s.f. of project drainage. c. The six drainage labels on the Culvert Permit Plan drawing indicate that they contain 548,856 s.f. of the project. Yet the Supplement sheet indicates that the total drainage area from which the allowable density is calculated totals 1,166,536 sf. That leaves 600,000+ sf that is not in a drainage area but is part of the project. Please account for the location of this s.f. area. d. The Culvert Permit Plan drawing indicates that the six drainage areas total 12.6 acres or 548,856 sf but the second page of the Stormwater Plan drawing provides numbers for the six drainage areas that total 28 acres or 1,219,680 s.f. One drawing shows 1.6 acres in Drainage Area 6 but another drawing shows 19.7 acres in that Drainage Area. We can't permit a specific density of impervious area without the correct project area. e. On the Stormwater II drawing, the total proposed impervious area for the project is shown as 95,927 sf or 8% impervious. This is in conflict with the 43,287 s.f. (or 3.7 %) of impervious shown on the Low Density Supplement. The PCN on file shows an overall imperviousness of 18% for the project. There should only be one impervious percentage for the portion of the property that will be permitted as low density. 4. There may be a more efficient method of designing stormwater swales. Please provide additional clarification regarding the flow aspects of the two 150' x 22' swales as these may not be required. Although we will need to have a better understanding of their purpose, it is possible that some of the stormwater going to those swales have already been "transported via vegetated conveyances" as is required in Water Quality Certification No. 3890. Please explain their purpose. If it is determined that they are necessary to achieve a treatment requirement, we will need some design information on a drawing to show how the water is diffused across the width of the swale. 5. We see several issues with the dry pond and level spreader design. Although we are not going to review these elements unless you decide to apply as a high density project, a cursory review of the drawings shows several problems with those proposals. Some of the elements that we saw are: The dry basin design is not designed consistent with our BMP Stormwater Manual and would appear to have stability issues. The emergency overflow at an elevation of 2641 feet is at the same elevation as the berm that makes up the basin. If there were a large rain event that filled up the design storm capacity and overflowed, the stormwater would also overflow at various points around the dry basin. On the eastern side, it would back up towards the level spreader and on the western side; it would overflow towards the floodway area. Unless unusual land stability methods were employed, we Adam King DWR# 14 -0770 Request for Additional Information Page 4 of 5 believe that the overflow would eventually erode the top of the berm, cause gullies that could eventually result in instability of the berm. We've asked about this before and Ms. Austin stated in her September 13, 2014 letter that the "detention basin is adequately sized to prevent any overflow onto the left side of the basin." We believe that the very small width of that berm at the 2641' elevation will not prevent overflow. Also, the Stormwater Manual also requires a foot of freeboard and 25% sediment storage in the basin design. We did not see that those were included although the earlier- submitted Supplement indicated that the freeboard was provided. The Culvert Permit Plan shows an outlet from the dry basin of 30' but no detail on the size of the energy dissipater pad for the outlet. b. The level spreader design is different from that specified in Chapter 9 of the Stormwater BMP Manual. If you choose to use this as a treatment device to achieve a higher density than 24 %, you will need to provide additional information on how it provides equal treatment to that shown in the Manual. The lack of essential engineering elements as listed above have prevented us from completing our review. Once these issues described above are clarified and the plans and all submittals are updated for consistency and accuracy, we will strive to provide a quick turn - around on our review. Please understand that the extensive review comments provided above are intended to assist you and your engineer in providing the necessary essentials of the application to allow adequate processing. Pursuant to Title 15A NCAC 02H .0502(e) / Title 15A NCAC 02H .1304(d), the applicant shall furnish all of the above requested information for the proper consideration of the application. If all of the requested information is not received in writing by the above - referenced due date, the Division will be unable to approve the application and it will be returned. The return of this project will necessitate reapplication to the Division for approval, including a complete application package and the appropriate fee. Please respond in writing by the above - referenced due date letter by sending four copies of all of the above requested information to the 401 & Buffer Permitting Unit, 1617 Mail Service Center, Raleigh, NC 27699 -1617. Please be aware that you have no authorization under the Section 401 of the Clean Water Act for this activity and any work done within waters of the state may be a violation of North Carolina General Statutes and Administrative Code. Adam King DWR# 14 -0770 Request for Additional Information Page 5 of 5 Please contact Tim Fox at 828 - 296 -4664 or tim.fox @ncdenr.gov, if you have general questions and Boyd Devane at 919 - 807 -6373 or boyd.devane @ncdenr.gov with questions specific to the stormwater management plan. Sincerely, G. Landon Davidson, P.G., Regional Supervisor Asheville Regional Office cc: Wanda Austin — wandaioyiceaustin @gmail.com (via email) David Brown - USACE Asheville Regulatory Field Office (via email) Andrea Leslie - NCWRC (via email) DWR ARO 401 files DWR 401 & Buffer Permitting Unit G: \WR \WQ \Haywood \401s \Non- DOT\Beaverdam Road \ADDINFO BeaverdamRoad 3- 25- 2015.docx