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Home My WebLink AboutWPO202000031 VSMP - SWPPP 2020-06-24 (2)SHIMP ENGINEERING, P.C. Design Focused Engineering Stormwater Management Plan Calculation Packet For: WPO 2020-00031 Byers Fill Site June 16, 2020 SHIMP ENGINEERING, P.C. Design Focused Engineering June 16, 2020 Mr. John Anderson County of Albemarle Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia 22902 Regaring: Byers Fill Site Stormwater Management Plan Dear John, Enclosed is the Stormwater Management Calculations Packet for the Byers Fill Site VSMP Plan. This project is proposing a soil fill on Samuel F Jr. Byers & Joann Byers property. The source of fill is HTC Hotel with a WPO-2018-00031. This project is located on 2856 Laurel Cove Road, Charlottesville, VA 22901 on Tax Map 46 Parcel 33HO and Tax Map 47 Parcel 1 C. The total area of both properties combined is 6.49 acres while the limits disturbance area is 0.99 acres. The stormwater management strategy for this site shall be achieved by maintaining sheet flow at the west side of the limits of disturbance, while it was determined that a conveyance channel is needed on the East and South East side of the limits of disturbance on the site. Because the location of the sheet flow did not change downstream nor did the volume of the concentrated runoff, the downstream properties are not impacted by neither the concentrated runoff nor by the sheet flow downstream. Therefore, the design is in compliance with the MS-19 and its conditions are met. Conveyance channel calculations: This conveyance channel is 193.1 ft long. It maintains a 3:1 side slope with a 1-foot depth and a total width of 6 feet for a length of 173.7 Ft, then the conveyance channel starts opening up gradually to blend in with the natural grade for the remaining 19.4 ft. The conveyance channel is designed to return to the natural grade of the site to achieve no increase in the runoff on this site after the stockpile. The conveyance channel has a minimum slope of 8.0% and a maximum slope of 30%. To ensure adequacy, the LD-268 form was used to perform the calculations for the 2-Year SHIMP ENGINEERING, P.( Design Focused Engineering velocity and the 10-Year Capacity. The Irrational Equation was used for calculating the Flow (Q) discharge for the 2-Year and the 10-Year. The flowrate for the 2-Year Storm was determined to be 1.89 cfs with a velocity of 4.97 Ft/Sec, while the 10-Year flowrate is 2.62 cfs with a depth of 0.52 ft. Further, the LD-268 calculations show the need for EC-3 Type I matting. The conveyance channel is designed to manage runoff from both the 2-year and the 10- year storms. The conveyance channel has capacity for the 10-year storm and will not have erosive velocities from the 2-year storm. If you have any questions about this calculation packet please do not hesitate to contact me at: stephaniekshimp-en in�g com or justin(kshimp-en ing eering com by phone at (434) 227- 5140. Stephanie Paul Shimp Engineering, PC SHIMP ENGINEERING, P.C. Design Focused Engineering Contents: Water Quantity Calculations: Pre-Dev Drainage Map VDOT LD-268 Roadside and Median Conveyance Channel Design Form TOC Calculations & Nomographs Independent Reports: Excerpt from NRCS Soils Report SHIMP ENGINEERING, P.C. Design Focused Engineering Water Quantity Calculations: Pre-Dev Drainage Map VDOT LD-268 Roadside and Median Conveyance Channel Design Form TOC Calculations & Nomographs /�Vll ll�l�l \IIIV-L/lll lll[L111111111V-ll\V✓Llil ll1111111VL(Yll�l ll 912 E HIGH ST PHONE: (434) 227-5140 CHARLOTTESVILLE. VA 22902 JUSTIN®SHIMP-ENGINEERING.COM ■ VV 1 YL-V Yr% lvlr% REVISED: 05-20-2020 111 111 111 111 111 1 I • BYERS FILL Modified LD-268 Roadside and Median Ditch Design Form Side Slope Min. Max n=0.05 Ditch C A CA Tc 12 110 Q2 Q10 :1 L :1 R Slope Slope Allowable Velocity 2-yr 10-yr Matting Type Freeboard Channel Depth SF A �C, INCR ACC Ft/Ft Ft/Ft *Velocity **Depth 1 0.35 69927.75 1 1.61 1 0.56 0.56 16.0 3.37 4.66 1 1.89 1 2.62 3 3 0.08 0.30 7.0 4.97 0.52 EC-3 TYPE 1 0.48 1.00 *2-yr Velocity calculations performed using steepest slope & 2-yr flow ** 10-yr Depth calculation performed using shallowest slope & 10-yr flow BYERS FILL Time of Concentration Calculations POSTDEV TOC 100 ft Overland Flow 1.35% slope 0.35 C-value 13.7 min Seelye Chart 220.5 ft S.C. Flow 10.27% slope 2.2 fps velocity 1.7 min. NEH Figure 15-4 193.1 ft Channel 32.0 ft height 0.6 min. Kirpich Chart TOC= 16.0 min. 35 I 30 V Paved 4 z 25 o .e 300 cr Bare o 2 0 N 200 Soil .� Poor Grass w z \Surface U_ 5 W w Average = .4 z 0.5 z u_ Grass U ao 15 w \ 2'0 So Dense Grass \ a �-� z g �- 70 Z 5.0 z 10 p 5 0 ' 2 0 nW. w = 40 10 z U 30 9 w z J Z 8 20 7 10 6 OVERLAND FLOW TIME (Seelye Chart) Source: Data Book for Civil Engineers, E.E. Seelye Plate 5-1 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.09 0.08 0.07 .°a 0.06 0.05 0.04 0.03 0.02 0.01 IA Cv ro 4 GOB Q w 0.005 1 1 1 Y I 1 l l I l W1 I I I I I / /1 1. 1 I I I I I I I I I 11 1 111 1 1 I Ci C� d Ll, co L1 Oq o� o cA m Ln cD L- 0C m o o 0 0 0 0 0 0 000— Velocity (ftfs) TRAVEL TIME FOR CHANNEL FLOW (Kirpich Chart) H (feet) 500 TC (min.) 200 100 L (feet) 10000 f-to 4P 50 4 r50500 le 5000 Z 4j Q b ~ = C 4J C Note: O � a (1) For use with natural channels; 5 41 a o (2) For paved channels, multiply c o v 10 v 10 Tt by 0.2 1000 E � E ~ o This was used because the x 4- 5 channel is manmade and 500 5 not natural L Of .y x 100 I 1 TIME OF CONCENTRATION OF SMALL DRAINAGE BASINS Source: VDOT Plate 5-3 SHIMP ENGINEERING, P.C. Design Focused Engineering Independent Reports: Excerpt from NRCS Soils Report USDA United States Department of Agriculture N RCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Albemarle County, Virginia May 11, 2020 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 0 38° 729" N v I 52 On i 38° 7' 11" N 726210 726280 726350 725420 726490 3 0 Map Scale: 1:2,730 if printed on A portrait (8.5" x 11") sheet Meters N 0 40 80 160 240 Feet 0 100 Z00 400 600 Map projection: Web Mentor Comer coordinates: WGS84 Edge tics: UTM Zone 17N WGS84 9 Custom Soil Resource Report Soil Map N 726210 726280 726350 726420 3 N 38' 729" N 38' 7' 11" N 726630 3 lV N N MAP LEGEND Area of Interest (AOI) 0 Area of Interest (AOI) Soils 0 Soil Map Unit Polygons im 0 Soil Map Unit Lines ■ Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit .4 Gravelly Spot 0 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 oa Sodic Spot Custom Soil Resource Report MAP INFORMATION A Spoil Area The soil surveys that comprise your AOI were mapped at 1:15,800. Stony Spot Very Stony Spot Warning: Soil Map may not be valid at this scale. Wet Spot Enlargement of maps beyond the scale of mapping can cause Other misunderstanding of the detail of mapping and accuracy of soil .- Special Line Features line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed Water Features scale. - Streams and Canals Transportation Please rely on the bar scale on each map sheet for map �}} Rails measurements. Interstate Highways Source of Map: Natural Resources Conservation Service US Routes Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Major Roads Local Roads Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts Background distance and area. A projection that preserves area, such as the Aerial Photography 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: Albemarle County, Virginia Survey Area Data: Version 13, Sep 17, 2019 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: May 20, 2019—Aug 1, 2019 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. 10 Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 27B Elioak loam, 2 to 7 percent 4.2 22.1 % slopes 27C Elioak loam, 7 to 15 percent 1.6 8.3% slopes 28C3 Elioak clay loam, 7 to 15 0.0 0.0% percent slopes, severely eroded 281D3 Elioak clay loam, 15 to 25 0.3 1.6% percent slopes, severely eroded 34B Glenelg loam, 2 to 7 percent 0.1 0.8% slopes 34C Glenelg loam, 7 to 15 percent 0.6 3.1 % slopes 3.2 39D Hazel loam, 15 to 25 percent 16.5% slopes 93C Watt channery silt loam, 7 to 15 1.4 7.4% percent slopes 93D Watt channery silt loam, 15 to 6.6 34.3% 25 percent slopes 93E Watt channery silt loam, 25 to 1.2 6.0% 45 percent slopes Totals for Area of Interest 19.1 100.0% 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 11 Custom Soil Resource Report 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 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 Iandform 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. 12 Custom Soil Resource Report Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. 13 Custom Soil Resource Report Albemarle County, Virginia 2713—Elioak loam, 2 to 7 percent slopes Map Unit Setting National map unit symbol: kb8y Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: All areas are prime farmland Map Unit Composition Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: loam H2 - 8 to 39 inches: silty clay H3 - 39 to 79 inches: silt loam Properties and qualities Slope: 2 to 7 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Moderate (about 6.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: B Hydric soil rating: No 14 Custom Soil Resource Report 27C—Elioak loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: kb8z Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Farmland of statewide importance Map Unit Composition Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: loam H2 - 8 to 39 inches: silty clay H3 - 39 to 79 inches: silt loam Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Moderate (about 6.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Hydric soil rating: No 15 Custom Soil Resource Report 28C3—Elioak clay loam, 7 to 15 percent slopes, severely eroded Map Unit Setting National map unit symbol: kb91 Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Not prime farmland Map Unit Composition Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: clay loam H2 - 8 to 39 inches: silty clay H3 - 39 to 79 inches: silt loam Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 6.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B Hydric soil rating: No Moderately high to 16 Custom Soil Resource Report 28D3—Elioak clay loam, 15 to 25 percent slopes, severely eroded Map Unit Setting National map unit symbol: kb92 Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Not prime farmland Map Unit Composition Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: clay loam H2 - 8 to 39 inches: silty clay H3 - 39 to 79 inches: silt loam Properties and qualities Slope: 15 to 25 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat): high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 6.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6e Hydrologic Soil Group: B Hydric soil rating: No Moderately high to 17 Custom Soil Resource Report 34B—Glenelg loam, 2 to 7 percent slopes Map Unit Setting National map unit symbol: kb9k Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: All areas are prime farmland Map Unit Composition Glenelg and similar soils: 90 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Glenelg Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: loam H2 - 8 to 28 inches: silty clay loam H3 - 28 to 80 inches: loam Properties and qualities Slope: 2 to 7 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): high (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: High (about 9.7 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: B Hydric soil rating: No Moderately high to 18 Custom Soil Resource Report 34C—Glenelg loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: kb9l Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Farmland of statewide importance Map Unit Composition Glenelg and similar soils: 85 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Glenelg Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: loam H2 - 8 to 28 inches: silty clay loam H3 - 28 to 80 inches: loam Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): high (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: High (about 9.7 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Hydric soil rating: No Moderately high to 19 Custom Soil Resource Report 39D—Hazel loam, 15 to 25 percent slopes Map Unit Setting National map unit symbol: kbb3 Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Not prime farmland Map Unit Composition Hazel and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hazel Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from graywacke sandstone and mica schist Typical profile H1 - 0 to 10 inches: loam H2 - 10 to 20 inches: loam H3 - 20 to 30 inches: channery loam H4 - 30 to 79 inches: bedrock Properties and qualities Slope: 15 to 25 percent Depth to restrictive feature: 20 to 40 inches to lithic bedrock Natural drainage class: Excessively drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.20 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 4.1 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B Hydric soil rating: No 20 Custom Soil Resource Report 93C—Watt channery silt loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: kbg7 Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Not prime farmland Map Unit Composition Watt and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Watt Setting Landform: Hills Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from graphite schist Typical profile H1 - 0 to 10 inches: channery silt loam H2 - 10 to 18 inches: very channery silt loam H3 - 18 to 28 inches: very channery silt loam H4 - 28 to 79 inches: bedrock Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: 20 to 40 inches to paralithic bedrock Natural drainage class: Somewhat excessively drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Very low to high (0.00 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low (about 2.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B Hydric soil rating: No 21 Custom Soil Resource Report 93D—Watt channery silt loam, 15 to 25 percent slopes Map Unit Setting National map unit symbol: kbg8 Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Not prime farmland Map Unit Composition Watt and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Watt Setting Landform: Hills Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down -slope shape: Linear Across -slope shape: Convex Parent material: Residuum weathered from graphite schist Typical profile H1 - 0 to 10 inches: channery silt loam H2 - 10 to 18 inches: very channery silt loam H3 - 18 to 28 inches: very channery silt loam H4 - 28 to 79 inches: bedrock Properties and qualities Slope: 15 to 25 percent Depth to restrictive feature: 20 to 40 inches to paralithic bedrock Natural drainage class: Somewhat excessively drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat): Very low to high (0.00 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low (about 2.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6e Hydrologic Soil Group: B Hydric soil rating: No 22 Custom Soil Resource Report 93E—Watt channery silt loam, 25 to 45 percent slopes Map Unit Setting National map unit symbol: kbg9 Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Not prime farmland Map Unit Composition Watt and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Watt Setting Landform: Hills Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down -slope shape: Linear Across -slope shape: Convex Parent material: Residuum weathered from graphite schist Typical profile H1 - 0 to 10 inches: channery silt loam H2 - 10 to 18 inches: very channery silt loam H3 - 18 to 28 inches: very channery silt loam H4 - 28 to 79 inches: bedrock Properties and qualities Slope: 25 to 45 percent Depth to restrictive feature: 20 to 40 inches to paralithic bedrock Natural drainage class: Somewhat excessively drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat): Very low to high (0.00 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low (about 2.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7e Hydrologic Soil Group: B Hydric soil rating: No 23