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HomeMy WebLinkAbout20032 Barker Farm - Stormwater Management Report - 20032 Barker20032 Barker Farm Solar Energy System 27 Nov 17 _________________________________________________________________________________________________________________ Existing Conditions Description: The 20032 Barker Farm, LLC Solar Energy System is located off Walter Canady Road in Hope Mills, Cumberland County, North Carolina. The property PIN number is 0422513534. The project site contains approximately 21.17 acres of agricultural fields and wooded lands. There are no structures located on the site. The existing soils on the site include: Goldsboro loamy sand (GoA), Lynchburg sandy loam (Ly), Pantego loam (Pg), Rains sandy loam (Ra), Torhunta and Lynn Haven soils (TR), Wagram loamy sand (WaB) and Woodington loamy sand (Wo). The site is 1.4% hydrolic soil group (HSG) B, 8.3% HSG B/D, 72.8% HSG A/D and 17.4% HSG A. The entire site drains toward the southwest direction towards Run of Gallberry Swamp which is considered a jurisdictional stream. These jurisdictional features include both intermittent and perennial classification. FIRM Panel 3720042200J indicate the site does not lie within a special flood hazard area. The surface water classification for the site is C; Sw. The site is located in the Lumber River basin. Project site Latitude and Longitude is 34.908071° and - 78.912788°. Description of Proposed Project: The proposed solar farm will consist of tracker solar panels, dual inverter/transformer areas and a chain link fence along the perimeter of the array. The project will also include temporary laydown and parking areas, and a permanent gravel driveway apron along Walter Canady Road The installation of the solar panels themselves will not generally create significant land disturbance. The panels will be mounted to racks, which are supported by a series of posts. The posts will be driven directly into the existing ground without excavation or land disturbance and the existing ground cover will be allowed to remain to the extent possible. Overall, approximately 13.8 acres of land will be disturbed by construction; this is our entire project limits. The project areas true disturbance is caused by clearing and grubbing, rubber tire vehicles accessing the site to distribute and install above grade material and a dozen or so small trenches (2’ wide, 36” deep) for wiring the array. The rack posts are mechanically driven directly into the ground. The entire disturbed area will be protected by silt fence with silt fence outlets. No change in drainage patterns (site drainage remains as sheet flow) or additional ponding of water will occur as a result of this project. At the completion of construction, the entire site will be seeded to create a good stand of grass. Erosion control measures for this site have been designed in accordance with the NCDENR Erosion and Sediment Control Planning and Design Manual (Revised 5/13). Stormwater Design: At the completion of construction, the entire site will be seeded with a permanent grass seed to create a good stand of grass. Since the panels are supported above the ground surface, grass is allowed to grow under the panels. Rainwater will sheet flow off the panels and onto the grass. The panels are therefore not considered to be impervious cover, as confirmed in the attached email from Julie Ventaloro with NCDENR-DQW, dated May 17, 2013. A copy of this letter is included in the attached exhibits. The proposed drive, inverter pads and rack posts will contribute a total of 27,373 sf of impervious surface. As shown in the 20032 Barker Farm Solar Power Generation Facility - Impervious Percentage Calculations included in in Appendix B, the post development impervious cover will be 2.97% of the total project area. Therefore, this project is considered Low Density and does not alter the pre- development stormwater runoff characteristics of the site. 20032 Barker Farm Solar Energy System 27 Nov 17 _________________________________________________________________________________________________________________ List of Exhibits: · Maps o NRCS Soils Map o NRCS Hydrologic Soil Group Map o USDA Soils Map - Hardbound o USGS Topo Map o FIRM Panel 3720042200J o Aerial Photo · Calculations o 20032 Barker Farm Site Impervious Calcs o NCDENR Impervious Opinion Email from Julie Ventaloro 9 Custom Soil Resource Report Soil Map 3864700386480038649003865000386510038652003864700386480038649003865000386510038652003865300689900 690000 690100 690200 690300 690400 690500 690600 690700 690800 689900 690000 690100 690200 690300 690400 690500 690600 690700 690800 34° 54' 44'' N 78° 55' 17'' W34° 54' 44'' N78° 54' 39'' W34° 54' 23'' N 78° 55' 17'' W34° 54' 23'' N 78° 54' 39'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84 0 200 400 800 1200 Feet 0 50 100 200 300 Meters Map Scale: 1:4,510 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Cumberland County, North Carolina Survey Area Data: Version 17, Sep 19, 2016 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Feb 14, 2011—Mar 3, 2011 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Cumberland County, North Carolina (NC051) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI GoA Goldsboro loamy sand, 0 to 2 percent slopes, Southern Coastal Plain 0.9 1.4% Ly Lynchburg sandy loam, 0 to 2 percent slopes 3.6 5.5% Pg Pantego loam 1.8 2.8% Ra Rains sandy loam, 0 to 2 percent slopes 19.9 30.8% TR Torhunta and Lynn Haven soils 23.2 35.9% WaB Wagram loamy sand, 0 to 6 percent slopes 11.2 17.4% Wo Woodington loamy sand 4.0 6.1% Totals for Area of Interest 64.5 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not Custom Soil Resource Report 11 mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Hydrologic Soil Group—Cumberland County, North Carolina Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/26/2017 Page 1 of 43864700386480038649003865000386510038652003864700386480038649003865000386510038652003865300689900690000690100690200690300690400690500690600690700690800 689900 690000 690100 690200 690300 690400 690500 690600 690700 690800 34° 54' 44'' N 78° 55' 17'' W34° 54' 44'' N78° 54' 39'' W34° 54' 23'' N 78° 55' 17'' W34° 54' 23'' N 78° 54' 39'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84 0 200 400 800 1200 Feet 0 50 100 200 300 Meters Map Scale: 1:4,510 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Cumberland County, North Carolina Survey Area Data: Version 17, Sep 19, 2016 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Feb 14, 2011—Mar 3, 2011 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—Cumberland County, North Carolina Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/26/2017 Page 2 of 4 Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit — Cumberland County, North Carolina (NC051) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI GoA Goldsboro loamy sand, 0 to 2 percent slopes, Southern Coastal Plain B 0.9 1.4% Ly Lynchburg sandy loam, 0 to 2 percent slopes B/D 3.6 5.5% Pg Pantego loam B/D 1.8 2.8% Ra Rains sandy loam, 0 to 2 percent slopes A/D 19.9 30.8% TR Torhunta and Lynn Haven soils A/D 23.2 35.9% WaB Wagram loamy sand, 0 to 6 percent slopes A 11.2 17.4% Wo Woodington loamy sand A/D 4.0 6.1% Totals for Area of Interest 64.5 100.0% Hydrologic Soil Group—Cumberland County, North Carolina Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/26/2017 Page 3 of 4 Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Cumberland County, North Carolina Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/26/2017 Page 4 of 4 Area (sf) Area (ac) % of Total 120,147 2.758 13.03% 797,784 18.315 86.50% 4,398 0.101 0.48% 0 0.000 0.00% 4,398 0.101 0.48% 922,329 21.174 100.00% Area (sf) Area (ac) % of Total 120,147 2.758 13.03% 774,809 17.787 84.01% 4,398 0.101 0.48% 0 0.000 0.00% 22,835 0.524 2.48% # of Pads Area/Pad (sf) 0 100 0 0.000 0.000% # of Inverters Area/Inverter (sf) 1 120 120 0.003 0.01% Posts/Rack # of Racks Area/Post (in2) 11 94 2.7 19 0.000 0.00% 9 6 2.7 1 0.000 0.00% 6 1 2.7 0 0.000 27,373 0.628 2.97% 922,329 21.174 100.00% Total Site Area = Proposed Drives (Gravel/Conc./Asphalt) (Assumes entire graded area) Proposed Impervious= Wooded Areas Impervious Pervious Impervious Pervious Agricultural Fields/Lawns Switchgear Pads Existing Structures to Remain Agricultural Fields/Lawns Inverter Total Rack Posts Total Inverter Areas Rack Posts Inverter Total Existing Drives to Remain Existing Impervious= 20032 Barker Farm Solar Power Generation Facility - Impervious Calculation Existing Conditions Drives (Gravel/Conc./Asphalt) Structures Total Site Area = Proposed Conditions Wooded Areas 20032 Barker Farm Site Impervious Calcs Impervious Calcs 8/2/2017 1 George Retschle From:Brent Niemann <bniemann@stratasolar.com> Sent:Friday, May 31, 2013 4:33 PM To:Cameron Weaver; Carol Miller Cc:George Retschle Subject:Fwd: Fixed-tilt rack mounted photovoltaic solar panels And here is Julie's response......... Brent Niemann, PE Civil Engineer Right-click here to download pictures. To help protect your privacy, Outlook prevented automatic download of this picture from the Internet. 1119 U.S. Hwy. 15-501 South Chapel Hill, NC 27517 O: 919.960.6015 x133 M: 919.268.7137 www.stratasolar.com ---------- Forwarded message ---------- From: Ventaloro, Julie <julie.ventaloro@ncdenr.gov> Date: Fri, May 17, 2013 at 10:16 AM Subject: RE: Fixed-tilt rack mounted photovoltaic solar panels To: Brent Niemann <bniemann@stratasolar.com> Cc: Michael Harvey <mharvey@orangecountync.gov>, "Joshua Crumpler PE, LEED AP" <JCrumpler@kleinfelder.com>, "Bennett, Bradley" <bradley.bennett@ncdenr.gov>, Cullen Morris <cmorris@stratasolar.com> Hi Brent,   Based on the information you provided, I would say that your solar panels could be considered pervious for purposes of  calculating percent imperviousness for compliance with the Water Supply or Phase 2 stormwater rules.  I conferred with  Mike Randall who coordinates the state’s Phase 2 program, and he agrees.  As you described, the concrete pads and  posts would be considered impervious.    If you will be using heavy machinery that compacts the soil and significantly  reduces infiltration, you may also need to consider those areas impervious.   Please let me know if you have further questions.   Julie Ventaloro 2 Coordinator, Water Supply Watershed Protection Program NC Division of Water Quality Wetlands & Stormwater Branch 1617 Mail Service Center, Raleigh, NC  27699‐1617 Phone:  (919) 807‐6370    Fax:  (919) 807‐6494 Website: http://watersupplywatershed.nc.gov   E‐mail correspondence to and from this address may be subject to the North Carolina Public Records Law and may be disclosed to third  parties.     From: Brent Niemann [mailto:bniemann@stratasolar.com] Sent: Wednesday, May 15, 2013 12:16 PM To: Ventaloro, Julie Cc: Michael Harvey; Joshua Crumpler PE, LEED AP; Bennett, Bradley; Cullen Morris Subject: Fixed-tilt rack mounted photovoltaic solar panels Good morning Julie. As a follow up to our conversation, I have attached some pertinent information for your review. We met with Michael Harvey at Orange County last week regarding an upcoming project we have received zoning approval for & are moving forward with construction drawings. Based on the information provided in this memo, your conversation with Terry Hackett was specific to "tracker" solar systems. We install fixed-tilt rack mounted PV panels facing south, which do not rotate. Our racks provide a minimum of 30" of clearance at the front & are tilted at 20-25 degrees from horizontal, making them less than 8' tall at the back. Each rack contains between 24-38 panels in portrait, depending on the equipment specified for the farm. This makes each rack between 45'-65' long. There is approximately a 1" gap between each panel on each rack (horizontal gap & vertical gap). Also, there is a minimum 6" gap between racks horizontally (sometimes more to accommodate site access). The rows of racks are spaced between 9'-20', to provide access & prevent racks from shading each other. I have attached some pictures to help with my descriptions. Also, here is a link to our website and you can look through various project photos (http://www.stratasolar.com/utility/utility- project-spotlight/). We have permitted over a dozen farms throughout the state (mostly through NCDENR regional offices) & our rack mounted panels have never been considered impervious. The only proposed impervious surfaces we install are the driven posts (cross sectional area is about 2.5 sq, in. each, about 3,000-4,000 per site based on soil conditions & system size) and pre-cast concrete pads for inverter/transformer equipment (about 100 sf each, 6- 10 per site). Overall the impervious calculations for our farm placed in an agricultural field, are less than 3 0.5%. We utilize logging mats during construction to provide access in wet, rutted areas. Following construction, we remove the mats, regrade, seed & stabilize. Based on this information, can you provide us your interpretation of how you would consider our solar farms from a pervious/impervious standpoint? Please feel free to call or email me if you have any questions or require additional information. Thanks Brent Brent Niemann, PE Civil Engineer Right-click here to download pictures. To help protect your privacy, Outlook prevented automatic download of this picture from the Internet. 1119 U.S. Hwy. 15-501 South Chapel Hill, NC 27517 O: 919.960.6015 x133 M: 919.268.7137 www.stratasolar.com