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Home My WebLink About20052116 Ver 3_More Info Received_20171030 Homewood, Sue From:Perry Isner <perry.isner@gmail.com> Sent:Monday, October 30, 2017 5:01 PM To:Homewood, Sue Cc:Gibby, Jean B CIV USARMY CESAW (US) Subject:\[External\] Re: Caleb's Creek Attachments:171030_CalebsCreek_PCNpdf.pdf; 171030_CalebsCreek_ImpactMap.pdf; 171030 _Calebs_NWP14impactstable.pdf; 1509374423929_1509394283866.jpg; 1509374351221_ 1509394283454.jpg; 1509373850345_1509394283085.jpg CAUTION: External email. Do not click links or open attachments unless verified. Send all suspicious email as an attachment to report.spam@nc.gov. Hi Sue, Apologies for getting back to you so late, I wanted to have one condensed reply and just got the signed PCN from Jeff Hatling with Kernersville today. Below are the responses to your questions, and attached is the updated PCN, impact table and map, and some additional pictures I took today for reference:  The stream impact table indicates that impact length was determined by pipe length. I mentioned this in our meeting, this needs to be changed to impacts determined as stream length. Although some of these may be close to the pipe length if they are straight sections of stream, it is rare that crossings are exactly the same length as the proposed pipe. Attached is the modified table of impacts for Nationwide 14, which refers to impact length rather than pipe length. As R1 is the only crossing location that has currently been surveyed, the other impact lengths were based upon preliminary crossing design and are thus conservative estimations, with stream impacts not to exceed the amounts requested.  Please provide plan views for impacts R2, R3 and R4. We currently don't have plan views of these crossings as these areas have not been surveyed and the thoroughfare routing for these crossings is still extremely conceptual in nature. I can provide rough, conceptual routing locations but they will be subject to change given that as we discussed during our meeting these crossings are likely not to be constructed eminently.  R2 is noted as an intermittent stream, however the profile view shows this as a triple barrel box culvert. That seems extreme for a small intermittent channel, can you elaborate on why that’s being proposed please. This stream was originally observed with no flow and therefore is shown on the map approved by the Corps as seasonal. However, it is a relatively large stream (see attached picture depicting R-2 crossing) with a sizable drainage area of at least 300 acres, much of which is impervious surface in the I-40 corridor and includes a large amount of stormwater control. Calculations for culvert sizing were approximated based upon the drainage area and ratio to crossing R- 1; however, these designs are based upon rough approximations and therefore not precise. If modifications from this current design are in fact necessary, it would likely be that culvert sizing would be reduced as all crossings were designed to be conservative for this initial phase.  Can you provide a table that matches up the impact sites with the stream call/jd numbering system. I wanted to find the stream forms for a few areas but can’t quite be sure I’m matching them up correctly. We did not include stream forms for these impact areas as we are planning to mitigate for all impacts and the Army Corps has agreed to accept payment for mitigation prior to each phase of the development. The first crossing, R-1, is a named perennial stream and only crossing R-3 would likely score less than 30. Stream forms for these impact areas can be provided if necessary.  The slope at impact R3 is pretty extreme, I haven’t been out there so can you describe the situation a little please? Typically when we see slopes like that we don’t require pipe burial and we often have concerns with stability at the outlet, even with a riprap pad. The slope calculations used for the preliminary crossing design were based upon 2-foot contours as these areas have not been surveyed for topo, and thus are conceptual in nature. This is, however, an area where the natural valley is relatively narrow, creating a potentially steep crossing slope (see attached picture depicting R-3 crossing).  You provided mitigation acceptance for 360 feet of roadway impacts. We discussed that the riprap pads adjacent to the culverts would not require mitigation if they were installed properly, however I don’t recall discussion (or have notes 1 that indicate) that we wouldn’t require mitigation for the extensive riprap impact at S-1. Originally S-1 was contemplated to require much less impact for riprap stabilization (100 linear feet), which was agreed not to require compensatory mitigation. However, there was concern about the 90 degree angle of the emergency spillway. Consequently, the spillway was re-designed to allow a more gradual angle when the emergency spillway is activated, resulting in the increase of the impact required for stabilization. The amount of impact required for this stabilization is conservative in nature, but was designed as a worst case scenario. Actual amount of riprap implemented for stabilization of spillway may be reduced during construction. However, if compensatory mitigation is determined to be necessary for this impact, applicant will likely propose that spillway be approved as originally designed.  Your letter indicates that the Town of Kernersville will be a co-applicant on the project (specifically the roadway impacts). I need a PCN that lists them as a co-applicant and a signature page for them also please. See attached updates to PCN including signature page. Please don't hesitate to call if you would like to discuss any of the provided responses or if you have further questions. Thanks! On Tue, Oct 24, 2017 at 1:09 PM, Homewood, Sue <sue.homewood@ncdenr.gov> wrote: Perry, I have a few questions and concerns about the Caleb’s Creek application:  The stream impact table indicates that impact length was determined by pipe length. I mentioned this in our meeting, this needs to be changed to impacts determined as stream length. Although some of these may be close to the pipe length if they are straight sections of stream, it is rare that crossings are exactly the same length as the proposed pipe.  Please provide plan views for impacts R2, R3 and R4  R2 is noted as an intermittent stream, however the profile view shows this as a triple barrel box culvert. That seems extreme for a small intermittent channel, can you elaborate on why that’s being proposed please.  Can you provide a table that matches up the impact sites with the stream call/jd numbering system. I wanted to find the stream forms for a few areas but can’t quite be sure I’m matching them up correctly.  The slope at impact R3 is pretty extreme, I haven’t been out there so can you describe the situation a little please? Typically when we see slopes like that we don’t require pipe burial and we often have concerns with stability at the outlet, even with a riprap pad.  You provided mitigation acceptance for 360 feet of roadway impacts. We discussed that the riprap pads adjacent to the culverts would not require mitigation if they were installed properly, however I don’t recall discussion (or have notes that indicate) that we wouldn’t require mitigation for the extensive riprap impact at S-1.  Your letter indicates that the Town of Kernersville will be a co-applicant on the project (specifically the roadway impacts). I need a PCN that lists them as a co-applicant and a signature page for them also please. Thanks, Sue Homewood Division of Water Resources, Winston Salem Regional Office Department of Environmental Quality 2 336 776 9693 office 336 813 1863 mobile Sue.Homewood@ncdenr.gov 450 W. 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