Soil Map Unit Descriptions


(1) Mixed Alluvial
This channel-dissected soil complex occurs in floodplains and drainageways, and is susceptible to flooding1. Soil materials range from soft organic silts and clays to dense gravel-sand-silt-clay alluvium. The seasonal high water table varies from 0 to 2.5 feet below the surface. Depth to hard bedrock ranges from 3 to 30 feet. Permeability is variable. Soil strength may be poor because of soft soil and seasonal saturation. Septic drainfields and infiltration trenches are poorly suited because of wetness and flooding potential. Stream bank erosion within these soils may result in undercutting of embankments on adjacent properties. Hydric soils, which may include nontidal wetlands, occur within this mapping unit2.

(2) Chewacla
Soils consist of silty and clayey alluvium eroded from schist, granite, and gneiss. This soil occurs on floodplains and terraces adjacent to active stream channels and is subject to flooding1. The seasonal high water table is 0.5 to 1.5 feet below the surface. Depth to hard bedrock ranges from 10 to 20 feet. Permeability is slow. Foundation support may be poor because of soft soil and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Suitability for septic drainfields and infiltration trenches is poor because of wetness, slow permeability and flooding potential. Hydric soils occur in low areas within the Chewacla mapping unit2.

(3) Congaree
Soils consist of silty and clayey alluvium eroded from schists, granites, and gneiss. This soil occurs along high terraces and floodplains, and is subject to flooding1. The seasonal high water table is 2.5 to 4 feet below the surface. Depth to hard bedrock ranges from 10 to 25 feet. Permeability is slow. Foundation support may be poor because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are needed to prevent wet basement problems. Suitability for septic drainfields and infiltration trenches is poor because of wetness, slow permeability and flooding potential.

(5) Wehadkee
Soils consist of organic silts and clays eroded from schists, granites, and gneiss. This soil occurs within floodplains and is subject to flooding1. The seasonal high water table is 0 to 0.5 foot below the surface. Depth to hard bedrock ranges from 8 to 20 feet. Permeability is slow. Foundation support may be poor because of soft soil and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Suitability for septic drainfields and infiltration trenches is poor because of wetness, slow permeability and flooding potential. Wehadkee is predominantly hydric and may contain potential nontidal wetlands2.

(6) Hyattsville
This soil occurs in drainageways and toe slopes, derived from Coastal Plain sediments eroded from upper slopes. Soil materials include clay, silt, sand and gravel. The seasonal high water table is one to two feet below the surface. Depth to hard bedrock ranges from 10 to 200 feet or more. Permeability is generally moderate. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are necessary to prevent wet basements. Surface grading is often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the high water table.

(8) Worsham
This soil occurs in lower drainageways, depressions, and toe slopes, derived from schists, granites, and alluvium. Soft clays and silts overlie silty and sandy decomposed rock. The seasonal high water table is 0 to 0.5 foot below the surface. Depth to hard bedrock ranges from 20 to 100 feet. Permeability is slow in the surface and moderate to moderately rapid in underlying materials. Foundation support may be poor because of soft soil and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Engineered drainage designs are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the seasonal high water table and slow permeability. Worsham is predominantly hydric and may contain potential nontidal wetlands2.

(10) Glenville
This soil occurs in drainageways and footslopes, derived from schists, granites, and alluvium. Clays and silts overlie silty and sandy decomposed rock. The seasonal high water table is one to two feet below the surface. Depth to hard bedrock ranges from 10 to 100 feet. Permeability is moderate. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are necessary to prevent wet basements. Surface grading is needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the water table.

(11) Bermudian
Soils consist of silty and clayey alluvial sediments eroded from sandstones, siltstones, and shales. This soil typically occurs at higher elevations within the floodplains, and is subject to flooding1. The seasonal high water table is 2.5 to 4 feet below the surface. Depth to hard bedrock ranges from 4 to 14 feet. Permeability is moderate. Foundation support may be poor because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are needed to prevent wet basement problems. Suitability for septic drainfields and infiltration trenches is poor because of the water table and flooding potential.

(12) Rowland
Soils consist of silty and clayey alluvium eroded from sandstones, siltstones, and shales. This soil occurs on middle-level floodplain elevations, and is subject to flooding1. The seasonal high water table is one to three feet below the surface. Depth to hard bedrock ranges from 4 to 10 feet. Permeability is slow. Foundation support may be poor because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are needed to prevent wet basement problems. Suitability for septic drainfields and infiltration trenches is poor because of the water table and flooding potential. Hydric soils may occur in low areas within the Rowland mapping unit2.

(13) Bowmansville
Soils consist of organic silt and clay alluvium eroded from sandstones, siltstones, and shales. This soil occurs in the floodplain at the base of adjoining upland slopes, and is subject to flooding1. The seasonal high water tables is zero to one foot below the surface. Depth to hard bedrock ranges from 4 to 12 feet. Permeability is slow. Foundation support may be poor because of soft soil and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Suitability for septic drainfields and infiltration trenches is poor because of wetness, slow permeability and flooding potential. Bowmansville is predominantly hydric and may contain potential nontidal wetlands2.

(14) Manassas
Soils consist of sandy, silty and clayey materials eroded from sandstones and shales. This soil occurs in drainageways. The seasonal high water table is one to two feet below the surface. Depth to hard bedrock is from three to eight feet. Permeability is moderate. Foundation support may be marginal because of soft soil in the upper two to four feet and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are necessary to prevent wet basements. Surface grading and subsurface drainage are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the water table and shallow depth to rock. Use of the bedrock as engineered fill, road embankment, and/or trench backfill is limited due to rapid disintegration of the rocks.

(15) Muck
This organic-rich mineral soil occurs in the floodplain and is susceptible to flooding1. Highly variable, stratified sandy, silty and clayey sediments underlay the organic surface. The seasonal high water table is at or above the surface for extended periods of time. Depth to hard bedrock ranges from 20 to 300 feet. Permeability is generally slow. Foundation support may be poor because of soft and very soft underlying strata and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Suitability for septic drainfields and infiltration trenches is poor because of wetness and flooding. Muck areas are largely wetland areas2.

(18) Rocky Land - Acidic Rock
Areas of shallow silty and sandy soils occur with schist, granite, and gneiss outcrops and surface boulders. Outcrops and boulders occupy 15 to 40 percent of the surface. Depth to hard bedrock ranges from 0 to 6 feet. Permeability is moderate to moderately rapid. Foundation support is good. Shallow bedrock and stoniness make these soils difficult to excavate and grade. Blasting may be required for below grade basements and excavations. Suitability for septic drainfields and infiltration trenches is poor because of shallow bedrock. This mapping unit generally occurs in association with Manor and Louisburg soils.

(19) Very Rocky Land - Acidic Rock
Areas of shallow silty and sandy soils occur with schist, granite, and gneiss outcrops and surface boulders. Outcrops and boulders occupy greater than 40 percent of the surface. Depth to hard bedrock ranges from 0 to 6 feet. Permeability is moderate to moderately rapid. Foundation support is good. Shallow bedrock and stoniness make these soils difficult to excavate and grade. Blasting may be required for below grade basements and excavations. Suitability for septic drainfields and infiltration trenches is poor because of shallow bedrock. This mapping unit generally occurs in association with Manor and Louisburg soils.

(20) Meadowville
This soil occurs in drainageways and footslopes, derived from schists, granites, and alluvium. Clays and silts overlie silty and sandy decomposed rock. Depth to seasonal high water table ranges from two to four feet. Depth to hard bedrock ranges from 10 to 100 feet. Permeability is moderate. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are necessary to prevent wet basements. Grading is required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the high water table.

(21) Manor
This silty and sandy soil occurs on sloping uplands underlain by micaceous schist. Depth to hard bedrock ranges from 5 to 100 feet, but may be shallower on steeper slopes. Permeability is moderate to moderately rapid. Foundation support is good for small buildings (three stories or less). A high mica content causes the soil to "fluff" when disturbed. The soil is difficult to compact, requiring engineering designs for use as structural fill. The soil is generally suitable for septic drainfields and infiltration trenches. Manor is highly susceptible to erosion.

(23) Captina
This predominantly silty and clayey soil occurs on high stream terraces along the Potomac River. A dense layer restricts drainage, creating a perched water table 1.5 to 2 feet below the surface. Permeability is slow in the subsurface. Foundation support is typically good. The subsoil may affect subsurface drainage. Foundation drains and waterproofing are needed to prevent wet basements. Suitability for septic drainfields and infiltration trenches is poor because of slow permeability and the perched water table. Grading and subsurface drainage are often required to eliminate wet yards.

(24) Elioak
This soil occurs on hilltops underlain by micaceous schist. Silty clays overlie silty and sandy decomposed rock. Depth to hard bedrock ranges from 5 to 100 feet. Permeability is moderate. Foundation support is favorable for small buildings (three stories or less). The soil is suitable for septic drainfields and infiltration trenches. A high mica content causes the soil to "fluff" up when disturbed. The soil is difficult to compact, requiring engineering designs for use as structural fill. Elioak is highly susceptible to erosion.

(26) Bertie
This soil consists of predominantly silty and clayey sediments on relatively flat landscapes in the Coastal Plain. Sandy strata may occur below four feet in some areas. The seasonal high water table is 1.5 to 2.5 feet below the surface. Depth to hard bedrock is greater than 50 feet. Permeability is moderately slow. Foundation support may be marginal to poor because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are necessary to prevent wet basements and crawl spaces. Surface grading and subsurface drainage may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the seasonal water table and slow permeability.

(27, 29) Legore (Ruxton)
These gritty and silty upland soil is underlain by diorite/diabase bedrock. The depth to hard rock is usually less than two feet. Permeability in the soils above bedrock is moderately rapid. Foundation support is favorable. Basements and excavations below existing grade may require blasting of the hard rock. Suitability for septic drainfields and infiltration trenches is marginal to poor because of the shallow depth to rock.

(28) Montalto silt loam
Montalto occurs in association with plastic Iredell soils on hilltops underlain by a diorite/diabase bedrock. A silty surface covers a clayey subsoil of lower plasticity than Iredell. Depth to bedrock ranges from two to six feet. Permeability is moderate. Foundation support is generally favorable. Suitability for septic drainfields and infiltration trenches is marginal to poor because of the shallow depth to rock.


(30) Huntington
This soil occurs on the first bottom floodplains adjacent to the Potomac River, and is subject to flooding1. A silty surface overlies stratified alluvial sediments. The seasonal high water table is three to five feet below the surface. Depth to hard bedrock ranges from 15 to more than 100 feet. Permeability is moderate. Foundation support may be poor because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are needed to prevent wet basement problems. Suitability for septic drainfields and infiltration trenches is poor because of flooding potential and the seasonal water table.

(31) Lindside
This soil occurs on the first bottom floodplains adjacent to the Potomac River, and is subject to flooding1. Silty sediments overlie silty clay alluvium. The seasonal high water table is 1.5 to 3 feet below the surface. Depth to hard bedrock ranges from 15 to more than 100 feet. Permeability is moderately slow. Foundation support may be poor because of soft soils and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are needed to prevent wet basement problems. Suitability for septic drainfields and infiltration trenches is poor because of the water table and flooding potential.

(32) Fairfax silt loam
This upland soil consists of predominantly silty old alluvium, typically 3-7 feet thick, overlying silty and sandy decomposed rock. A discontinuous dense layer results in a "perched" seasonal water table at 1.5 to 2.5 feet below the surface. Depth to hard bedrock is 10 to 100 feet. Permeability is moderately slow in the dense layer and moderate in the underlying soil. With proper drainage, the soil typically provides adequate support for small buildings (3 stories or less). Exterior foundation drains and waterproofing are necessary to prevent wet basements. Grading and subsurface drains may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is marginal because of slow permeability and the perched water table.

(33) Melvin
This soil occurs on the first bottom floodplains adjacent to the Potomac River, and is subject to flooding1. Silty sediments overlie silty clay alluvium. The seasonal high water table is zero to one foot below the surface. Depth to hard bedrock ranges from 15 to more than 100 feet. Permeability is moderate. Foundation support may be poor because of soft soil and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Suitability for septic drainfields and infiltration trenches is poor because of wetness and flooding potential. Melvin is predominantly hydric and may contain potential nontidal wetlands2.

(34) Woodstown
This soil occurs in sandy sediments on nearly level landscapes in the lower Coastal Plain. Soil materials are primarily sandy loams to sandy clay loams, with a dense subsurface. The seasonal high water table is 1.5 to 2.5 feet below the surface. Depth to hard bedrock ranges from 50 to more than 300 feet. Permeability is moderately rapid in the surface and moderately slow in the subsurface. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains and waterproofing are necessary to prevent wet basements and crawl spaces. Grading and subsurface drainage may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the seasonal water table.

(35) Manteo
This shallow soil occurs primarily on steeper sideslopes underlain by micaceous schist. A thin silty surface overlies partly weathered schist and slate fragments. Depth to hard bedrock is usually less than 15 inches. Permeability is moderately rapid. The soil typically provides favorable support for small buildings (three stories or less). Because of a high mica content, the soil tends to "fluff" up when disturbed and is difficult to compact, requiring engineering designs for use as structural fill. Suitability for septic drainfields and infiltration trenches is poor because of the shallow depth to rock. Manteo is highly susceptible to erosion.

(37, 38) Beltsville
This gravelly and silty soil occurs on hilltops in the Coastal Plain and on old Coastal Plain terraces over weathered schists and granites. A dense layer is encountered at depths of 2 to 2.5 feet. Depth to hard bedrock is typically greater than 50 feet. Permeability of the dense layer is very slow, resulting in a perched seasonal high water table 1.5 to 2.5 feet below the surface. Foundation support is typically good with proper drainage. Foundation drains and waterproofing are necessary to prevent wet basements. Grading and subsurface drainage is usually required to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of slow permeability and the perched water table.

(39) Othello
This silty and clayey soil occurs on nearly level landscapes in the Coastal Plain. Lower areas along Dogue Creek are within the floodplain1. Underlying strata vary from sand to soft clays. Organic strata (peat or muck) may be encountered. The seasonal high water table is 0 to 0.5 foot below the surface. Depth to bedrock is greater than 50 feet. Permeability is slow in the surface and moderate to moderately rapid in underlying sands. Foundation support may be poor because of soft to very soft underlying strata and seasonal saturation. Basements below existing grade are not recommended because of severe wetness problems. Engineered drainage designs are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of wetness and slow permeability. Othello is predominantly hydric and may contain potential nontidal wetlands2.

(40) Mecklenburg
This soil, formed in weathered diabase materials, occurs on hilltops and sideslopes in close association with plastic Iredell soils. A silty surface overlies a sticky plastic clay subsoil. Sandy clays and clayey sands occur between the clay layer and bedrock in some places. A "perched" seasonal high water table occurs above the clays, 3 to 4 feet below the surface. Depth to hard bedrock is usually from 3 to 15 feet. Permeability is slow. Foundation footings must extend below the soft plastic clays, generally to bedrock, to ensure competent building support. Foundation drains and waterproofing are necessary to prevent wet basements and crawl spaces. Surface grading and subsurface drainage may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the perched water table, plastic clays, and shallow depth to rock. Deep basements and excavations may require blasting in hard bedrock.

(41) Rocky Land - (Iredell)
This mapping unit occurs on hilltops and sideslopes in association with the Iredell soils in the diabase areas. Frequent rock outcrops or boulders occupy 20 to 50 percent of the surface. Plastic clay subsoil may occur one to three feet below the surface. The depth to seasonal high water table varies from one to greater than ten feet. The depth to hard bedrock varies from zero to 15 feet. Foundation support is good on bedrock, but may be poor in areas with plastic clay subsoil. Suitability for septic drainfields and infiltration trenches is poor because of plastic clays and shallow depth to rock. The shallow bedrock and stoniness make these soils difficult to excavate and grade. Deep basements and excavations may require blasting in the hard bedrock.

(42) Very Rocky Land - (Iredell)
This mapping unit occurs on hilltops and sideslopes in association with the Iredell soils in the diabase areas. Frequent rock outcrops or boulders occupy over 50 percent of the surface. Plastic clay subsoil may occur one to three feet below the surface. The depth to seasonal high water table varies from one to greater than ten feet. The depth to hard bedrock varies from zero to 15 feet. Foundation support is good on bedrock, but may be poor in areas with plastic clay subsoil. Suitability for septic drainfields and infiltration trenches is poor because of plastic clays and shallow depth to rock. The shallow bedrock and stoniness make these soils difficult to excavate and grade. Deep basements and excavations may require blasting in the hard bedrock.

(43) Masada gravelly loam
Masada is found on high terraces, in loamy and gravelly material washed from soils of the Piedmont Upland. A sticky, plastic clay subsoil may restrict drainage and be difficult to manipulate and compact when wet. Depth to hard bedrock ranges from 30 to 150 feet. Permeability is moderately slow. Foundation support is typically good. Exterior foundation drains and waterproofing are needed to prevent wet basements. Grading and subsurface drainage are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is marginal because of slow permeability.

(44) Caroline
This soil occurs in clayey sediments on hilltops and sideslopes in the Coastal Plain. A plastic clay subsoil may restrict drainage. Depth to hard bedrock is greater than 30 feet. Permeability is moderately slow. Foundation support is marginal because of the plastic clays. Foundation drains and waterproofing are necessary to prevent wet basements. Grading and subsurface drainage are often necessary to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of the clay and slow permeability.

(45) Matapeake
This soil occurs on uplands in sand, silt and clay sediments of the lower Coastal Plain. Sandy clay loam, clay loam, and silty clay loam soils are typical. A dense silty clay loam layer may be present two to three feet below the surface in some areas. Depth to bedrock is typically greater than 200 feet. Permeability is moderate, but may be moderately slow where the dense layer is present. Foundation support is generally favorable. Subsurface drainage may be needed to prevent wet basements and yards where the dense layer occurs. Suitability for septic drainfields and infiltration trenches is good, except in areas of dense soil.

(46) Mattapex
This soil occurs on uplands in sand, silt, and clay sediments of the lower Coastal Plain. Sandy clay loam, clay loam, and silty clay loam soils are typical. A dense layer occurs 2.5 to 3 feet below the surface. A "perched" seasonal high water table is found above the dense layer, one to two feet below the surface. Depth to hard bedrock is typically greater than 200 feet. Permeability is moderately slow. Foundation support may be marginal because of occasional soft soil and seasonal saturation. Foundation drains and waterproofing are needed to prevent wet basements. Grading and subsurface drainage are often necessary to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of slow permeability and the perched water table.

(47) Dragston
This soil occurs on nearly level uplands in sandy and clayey Coastal Plain sediments. Sandy loams and sandy clay loams are predominant in the upper five feet. The seasonal high water table is 1.5 to 2.5 feet below the surface. Depth to hard bedrock is typically greater than 200 feet. Permeability is moderately rapid. Foundation support may be marginal because of seasonal saturation. Foundation drains (interior and exterior) and waterproofing are needed to prevent wet basements. Grading and subsurface drainage are often necessary to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the seasonal water table.

(48) Iredell
This highly plastic soil occurs on hilltops and sideslopes, formed in weathered diabase materials. A silty surface overlies a sticky plastic clay subsoil one to three feet thick. Sandy clays and clayey sands occur below the clay layer. A perched seasonal high water table, above the clays, is one to two feet below the surface. Depth to hard bedrock is usually from 3 to 15 feet. Permeability is slow. Foundation footings must extend below the soft plastic clays, generally to bedrock, to ensure competent building support. Foundation drains, grading, and waterproofing are necessary to prevent wet basements and crawl spaces. Grading and subsurface drainage may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the plastic clays, perched water table, and shallow depth to bedrock. Deep basements and excavations may require blasting.

(49) Lunt
This extremely variable soil is found on hilltops and sideslopes in sands, silts, and clays of the Coastal Plain. Soil materials vary from sands to clays. Where clay subsoils are present, a perched seasonal water table may be present above the clay. Depth the hard bedrock is typically greater than 75 feet. The soils are stable when underlain with sands. However, Lunt soils in close proximity to areas of the Marine Clays should be analyzed for foundation support and slope stability. Permeability of the subsoil varies depending upon the soil material. Foundation drains, grading, and waterproofing are necessary to prevent wet basements and crawl spaces where clays are present. Suitability for septic drainfields and infiltration trenches is good in the sandy subsoil and poor in the clayey subsoil.

(50) Iredell-Mecklenburg, Stony
This highly plastic soil occurs on hilltops and sideslopes, derived from weathered diabase. A silty surface covers a sticky plastic clay subsoil one to three feet thick. Sandy clays and clayey sands occur below the clay layer. Numerous surface boulders may be present. A perched seasonal high water table, above the clay, is one to two feet below the surface. Depth to hard bedrock is usually 3 to 15 feet. Permeability

(51) Keyport
This soil occurs on nearly level landscapes in predominantly silty and clayey sediments of the Coastal Plain. Slowly permeable clays occur in the subsoil and a seasonal high water table may be present within three to four feet of the surface. Sandy strata may occur below five feet. Depth to hard bedrock is greater than 200 feet. Foundation support is fair provided that drainage is addressed. Foundation drains and waterproofing are needed to prevent wet basements. Grading may be necessary to eliminate wet yards. Suitability for septic drainfields and infiltration is marginal to poor because of the water table and slow permeability.

(52) Elbert - (Iredell Group)
This wet, plastic soil occurs in drainageways and footslopes in materials derived from weathered diabase and alluvium. Slowly permeable plastic clay subsoils occur 2 to 4 feet below the surface. The seasonal high water table is 0 to 0.5 foot below the surface. The depth to bedrock varies from 3 to 15 feet. Foundation footings must extend below the soft plastic clays, generally to bedrock, to ensure competent building support. Basements below existing grade are not recommended because of potential severe wetness problems. Engineered drainage designs are often required to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of wetness, plastic clays and shallow depth to bedrock. Elbert is predominantly hydric and may contain potential nontidal wetlands2.

(53) Lenoir
This soil occurs in loamy and clayey sediments on nearly level landscapes in the lower Coastal Plain. A silty surface overlies a slowly permeable clayey subsoil which has a moderate shrink-swell potential. The seasonal high water table is 0.5 to 1.5 feet below the surface. Depth to bedrock is typically greater than 200 feet. Foundation support is marginal because of the clays and seasonal saturation. Foundation drains (exterior and interior), surface grading, and waterproofing are necessary to prevent wet basements and crawl spaces. Grading is often required to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of the seasonal water table and slow permeability.

(54) Sassafras
This soil occurs on hilltops and sideslopes in sandy and clayey Coastal Plain sediments. The upper five feet consists of predominantly sandy and sandy clay loam materials. Depth to hard bedrock is greater than 200 feet. Permeability is moderate to moderately rapid. The soil typically provides adequate support for small buildings (three stories or less) and is suitable for most urban and residential uses.

(55) Glenelg
This soil occurs on hilltops and sideslopes underlain by micaceous schist. Silts and clays overlie silty and sandy decomposed rock. Depth to hard bedrock ranges from 5 to 100 feet. Permeability is moderate to moderately rapid. Foundation support for small buildings (three stories or less) is typically suitable. Because of a high mica content, the soil tends to "fluff" up when disturbed and is difficult to compact, requiring engineering designs for use as structural fill. This soil is suitable for septic drainfields and infiltration trenches. Glenelg is highly susceptible to erosion.

(56) Kempsville
This soil is found on hilltops in silty and sandy sediments of the Coastal Plain. A discontinuous dense layer may occur within two to three feet of the surface. Where present, this dense layer of slow permeability results in a "perched" seasonal water table within two to three feet of the surface. Depth to bedrock is greater than 40 feet. Building support is typically favorable with proper drainage. Foundation drains (exterior), waterproofing, and surface grading are needed to prevent wet basements or crawl spaces. Grading and subsurface drainage may be necessary to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is marginal because of slow permeability and the perched water table.

(57) Brecknock loam
This sandy to sandy clay loam soil occurs on hilltops and sideslopes underlain by gray baked sandstones. Depth to hard bedrock is 3 to 8 feet. Soil permeability is moderate. Bedrock may restrict subsurface water movement. Foundation support is generally good. Grading and subsurface drainage may be needed to prevent wet yards. Suitability for septic drainfields and infiltration trenches is marginal because of shallow rock. Use of this bedrock in engineered fill, road embankment, or trench backfill is limited due to rapid weathering. Added topsoil may be needed in shallow areas to provide adequate rooting depth for lawns, trees, and landscape plants.

(59) Orange
This plastic clay soil occurs on hilltops and sideslopes over greenstone bedrock. A thin silty surface overlies a plastic clay subsoil. The plastic clay, generally one to two feet thick often extends to bedrock in gently sloping hilltop areas. A perched seasonal water table, resulting from the slow permeability of the subsoil and underlying bedrock, is 0.5 to 1 foot below the surface. Depth to hard bedrock ranges from 4 to 15 feet. Building support is low in the soft plastic clays, but good on bedrock. Foundation drains, grading, and waterproofing are necessary to prevent wet basements and crawl spaces. Grading and subsurface drainage may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the plastic clays, perched water table, and shallow depth to bedrock. Deep basements and excavations may require blasting. Fibrous asbestos minerals may occur in the greenstone bedrock3. These fibers may become airborne during excavation and blasting operations. Worker protection and dust control measures are required in such instances.

(60) Appling
This soil, derived from granite and gneiss, occurs on hilltops and sideslopes. Silts and clays overlie clayey and sandy decomposed rock. Sticky, plastic clays may occur within the subsoil. Depth to hard bedrock ranges from 10 to 75 feet. Permeability is moderate to moderately slow in the upper soil. Subsurface permeability is typically moderate to moderately rapid, but may include relatively impermeable clay seams. The soil typically provides favorable support for small buildings (3 stories or less). The plastic subsoils are difficult to compact and move when wet. Deep septic drainfields and infiltration trenches (>6 feet) may be required because of slow subsoil permeability. Appling is highly susceptible to erosion.

(61) Loamy and Gravelly Sediments
This soil unit is located primarily on steep hillsides in the Coastal Plain. Soil materials include "bank run" gravels and sands mixed with layers of silts and clays. Layers of plastic clays may be found in areas where Marine Clays occur. The areas of this soil that are located west of I-95 are generally stable except for a few isolated areas of clays in terrace remnants that overlie weathered granite. Areas east of I-95, especially in proximity to mapped areas of Marine Clay, should be analyzed for foundation support and slope stability. Permeability, high water table and drainage conditions are variable. Suitability for urban and residential use is site-specific, depending on actual soil conditions.

(62) Brecknock gravelly silt loam
This silty and silty clay soil occurs on hilltops and sideslopes underlain by gray baked shales. Depth to hard bedrock is 3 to 8 feet. Soil permeability is moderate. Bedrock may restrict subsurface water movement. Foundation support is generally good. Grading and subsurface drainage may be needed to prevent wet yards. Suitability for septic drainfields and infiltration trenches is marginal because of possible shallow rock. Use of this bedrock in engineered fill, road embankment, or trench backfill is limited due to rapid weathering. Added topsoil may be needed in shallow areas to provide adequate rooting depths for lawns, trees, and landscape plants.

(63) Louisburg
This silty to sandy soil occurs on steep slopes underlain by granite and gneiss. Depth to hard bedrock is typically from 4 to 50 feet. Permeability is rapid. The soil provides good foundation support for buildings. The shallow depth to hard rock (1 to 4 feet) in some places decreases the potential suitability of these soils for septic drainfields and infiltration trenches. Louisburg is highly susceptible to erosion.

(64) Silty and Clayey Sediments
This unit occurs primarily along steep hillsides and adjacent to drainageways in the Coastal Plain. It consists predominantly of silty and clayey strata, but may contain thin layers and lenses of sand, gravel and Marine Clays. Soil properties are variable within this unit and low bearing strata and perched seasonal high water tables may be present. This unit may contain deposits of Marine Clay and should be analyzed for potential shrink-swell and slope stability problems. Suitability for septic drainfields and infiltration trenches is poor because of slow permeability and potential plastic clay and slope instability problems.

(65) Colfax
The soil, derived from granite, gneiss and alluvium, occurs in drainageways, footslopes, and upland flats. Sandy and loamy soils overlie a dense clayey layer. This slowly permeable layer, 1.5 to 3 feet below the surface, is usually 3 feet thick. Slowly permeable clayey soil typically occurs below the compact layer. A perched seasonal water table, above the dense layer, is 0.5 to 1.5 feet below the surface. Depth to hard bedrock is from 6 to 25 feet. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains (interior and exterior) and waterproofing are necessary to prevent wet basements. Grading is needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the seasonal water table and slow permeability.

(66) Lloyd
This red soil occurs on hilltops underlain by schist and greenstone. A loamy surface overlies a clayey subsoil. Depth to hard rock is from 4 to 30 feet. Permeability is moderate to moderately slow. The soil typically provides adequate support for small buildings (three stories or less), and is favorable for most urban and residential uses. Areas of greenstone bedrock may contain naturally occurring fibrous asbestos minerals3. These fibers may become airborne during excavation and blasting operations. Worker protection and dust control measures are required in such instances.

(67) Penn
This sandy and silty soil occurs on hilltops in weathered sandstone. Hard bedrock is three to five feet below the surface. Permeability is moderately rapid, but may be restricted by relatively un-fractured bedrock in some areas. Foundation support is generally good. Grading and subsurface drainage may be needed to prevent wet yards. Suitability for septic drainfields and infiltration trenches may be limited in areas of shallow bedrock. Use of this bedrock in engineered fill, road embankment, or trench backfill is limited due to rapid disintegration. Additions of topsoil may be needed in shallow areas to provide adequate rooting depths for lawns, trees, and landscape plants.

(68) Roanoke
This soil occurs in clayey alluvium on low stream terraces in the Piedmont Upland. The depth to seasonal high water table is from zero to one foot. Depth to bedrock is 8 to 20 feet. Permeability is slow. Flooding may occur following storm events1. Foundation support may be poor because of soft soil and seasonal saturation. Basements below original ground are not recommended because of severe wetness problems. Suitability for septic drainfields and infiltration trenches is poor because of wetness, slow permeability, and flooding potential. Roanoke is a hydric soil and may contain potential nontidal wetlands.

(69) Enon
This soil occurs on hilltops and sideslopes over greenstone and schist. The silty clay subsoil has moderate to high plasticity. A seasonal high water table, over clay or bedrock, is 2 to 6 feet below the surface. Depth to hard bedrock is typically 2 to 6 feet. Permeability is moderately slow. Foundation support is poor in the clay subsoil, but good on bedrock. Foundation drains and waterproofing are necessary to prevent wet basements and crawl spaces. Grading and subsurface drainage may be needed to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of plastic clays, the high water table, and shallow depth to bedrock. Deep basements and excavations may require blasting. The greenstone bedrock may contain naturally occurring fibrous asbestos minerals3. These fibers may become airborne during excavation and blasting operations. Worker protection and dust control measures are required in such instances.

(70) State
This sandy to silty soil occurs on high stream terraces in the Coastal Plain. Flooding may occur following storm events1. The seasonal high water table is four to six feet below the surface. Depth to hard bedrock is 8 to 20 feet. Permeability is moderate. Foundation support is typically good with proper drainage. Foundation drains and waterproofing are needed to prevent wet basements. Grading may be required to eliminate wet yards. Septic drainfields and infiltration trenches are marginally suited because of the high water table and flooding potential.

(71) Bucks silt loam
This silty and clayey soil occurs on hilltops in weathered shale and sandstone. Hard bedrock is three to eight feet below the surface. Permeability is moderate, but may be restricted by un-fractured bedrock in some areas. Foundation support is generally good. Grading and subsurface drainage may be needed to prevent wet yards. Septic drainfields and infiltration trenches may be limited in areas of shallow bedrock. Use of this bedrock in engineered fill, road embankment, or trench backfill is limited due to rapid disintegration.

(72) Bucks loam
This sandy and clayey soil occurs on hilltops in weathered sandstone. Hard bedrock is three to eight feet below the surface. Permeability is moderate, but may be restricted by un-fractured bedrock in some areas. Foundation support is generally good. Grading and subsurface drainage may be needed to prevent wet yards. Septic drainfields and infiltration trenches may be limited in areas of shallow bedrock. Use of this bedrock in engineered fill, road embankment, or trench backfill is limited due to rapid disintegration.

(73) Penn silt loam
This silty soil occurs on hilltops and sideslopes over red sandstones and shales. Depth to hard bedrock is less than three feet. Permeability is moderate to moderately rapid, but may be restricted by un-fractured bedrock. Foundation support is good. Grading and drainage may be needed to prevent wet yards. Shallow bedrock may limit septic drainfields and infiltration trenches. The bedrock disintegrates rapidly, limiting its use in engineered fill, road embankment, or trench backfill. Topsoil may be needed to increase rooting depths for lawns, trees, and landscape plants.

(75) Penn loam
This loamy soil occurs on hilltops and sideslopes over red sandstones. Depth to hard bedrock is less than two feet. Permeability is moderate, but may be restricted by un-fractured bedrock. Foundation support is good. Grading and drainage may be needed to prevent wet yards. Septic drainfields and infiltration trenches are poorly suited because of shallow bedrock. Use of this bedrock in engineered fill, road embankment, or trench backfill is limited due to rapid disintegration. Topsoil may be needed to increase rooting depths for lawns, trees, and landscape plants.

(76) Calverton loam
This silty to sandy clay soil occurs in drainageways and footslopes underlain by sandstone. Slowly permeable subsoil clays have a medium plasticity. The seasonal high water table is 0.5 to 2 feet below the surface. Depth to hard bedrock is three to eight feet. Foundation support may be poor because of soft plastic soil and seasonal saturation. Basements below existing grade are not recommended because of potential wetness problems. Engineered drainage is often needed to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of slow permeability, high water table, and shallow bedrock. The bedrock disintegrates rapidly, limiting its use in engineered fill, road embankment, and trench backfill.

(77) Penn shaly silt loam
This silty to clayey soil occurs on hilltops and sideslopes over shale. Depth to hard bedrock is less than two feet. Permeability is moderate to moderately rapid, but may be restricted by un-fractured bedrock. Foundation support is good. Grading and drainage may be needed to prevent wet yards. Septic drainfields and infiltration trenches are poorly suited because of shallow bedrock. Use of this bedrock in engineered fill, road embankment, or trench backfill is limited due to rapid disintegration. Topsoil may be needed to increase rooting depths for lawns, trees, and landscape plants.

(78) Calverton silt loam
This silty to clayey soil occurs in drainageways and footslopes underlain by shale. Slowly permeable subsoil clays have a medium plasticity. The seasonal high water table is 0.5 to 2 feet below the surface. Depth to hard bedrock is three to eight feet. Foundation support may be poor because of soft plastic soil and seasonal saturation. Basements below existing grade are not recommended because of potential wetness problems. Engineered drainage is often needed to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of slow permeability, high water table, and shallow bedrock. The bedrock disintegrates rapidly, limiting its use in engineered fill, road embankment, and trench backfill.

(79) Kelly
The silty and clayey soil occurs on hilltops and sideslopes underlain by diabase and baked shales and sandstones. A thin plastic clay layer often overlies bedrock. A seasonal high water table, one to two feet below the surface occurs above clay or bedrock. Depth to bedrock is two to eight feet. Permeability is moderately slow. Foundation support is good on bedrock, but poor in the plastic subsoil. Foundation drains and waterproofing are necessary to prevent wet basements. Grading and subsurface drainage are needed to prevent wet yards. Septic drainfields and infiltration trenches are poorly suited because of plastic clays, high water table, and shallow bedrock. The bedrock disintegrates rapidly, limiting its use in engineered fill, road embankment, and trench backfill.

(80) Croton
This silty to clayey soil occurs in drainageways and footslopes underlain by shale and sandstone. Subsoil clays have medium to high plasticity. The seasonal high water table is 0 to 0.5 foot below the surface. Depth to hard bedrock is from three to eight feet. Permeability is moderately slow. Foundation support may be poor because of soft or plastic subsoils and seasonal saturation. Basements below existing grade are not recommended because of potential wetness problems. Grading and subsurface drainage are often required to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of slow permeability, high water table, and shallow bedrock. The bedrock disintegrates rapidly, limiting its use as engineered fill, road embankment, and trench backfill. Croton is predominantly hydric and may contain potential nontidal wetlands2.

(83) Galestown
This soil occurs on nearly level landscapes in the lower Coastal Plain. Soil materials range from sandy loams to sands. Depth to bedrock is from 50 to 500 feet. Permeability is rapid. The soil provides adequate support for small buildings (three stories or less), and is suitable for most urban and residential uses.

(84) Fallsington
This sandy to sandy clay soil occurs on nearly level landscapes in the Coastal Plain. Low areas along Dogue Creek are within the floodplain1. Soft clay layers be included in the predominantly sandy soil. The seasonal high water table is 0 to 0.5 foot below the surface. Permeability is moderate to moderately rapid. Foundation support may be poor because of seasonal saturation and soft soil. Basements below grade are not recommended because of potential severe wetness problems. Engineered drainage is often needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of wetness and slow permeability. Fallsington is predominantly hydric and may contain potential nontidal wetlands2.

(85) Elkton
This wet soil occurs on nearly level landscapes in the lower Coastal Plain. Low areas of this soil, near larger streams, are within the floodplain1. A silty surface overlies silty and clayey subsoils. Organic strata (peat and muck) may be encountered in some areas. The clays typically have a high shrink-swell potential that has resulted in foundation damage on some existing residential dwellings. The seasonal high water table is 0 to 0.5 foot below the surface. Depth to bedrock is greater than 200 feet. Permeability is slow to very slow. Foundation support may be poor because of soft soils, plastic clay, and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Engineered drainage designs are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of wetness and slow permeability. Elkton is predominantly hydric and may contain potential nontidal wetlands2.

(86) Klej
This soil occurs on nearly level landscapes in the lower Coastal Plain. Soil materials are primarily sands and loamy sands. The seasonal high water table is 1 to 2.5 feet below the surface. Depth to bedrock is greater than 200 feet. Permeability is rapid. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains and waterproofing are necessary to prevent wet basements and crawl spaces. Grading and subsurface drainage may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the water table.

(87) Wickham
This soil occurs on low stream terraces in the Piedmont Upland and Coastal Plain. Flooding may occur following storm events1. Silty and clayey sediments are underlain with coarser textured materials. Depth to bedrock is from 20 to 100 feet. Permeability is moderate to moderately slow. Foundation support is typically adequate for small buildings (three stories or less). Suitability for septic drainfields and infiltration trenches may be marginal because of slow permeability.

(88) Hiwassee silt loam
This soil occurs on high stream terraces in the Piedmont Upland and Coastal Plain. Flooding may occur following severe storm events1. Silty and clayey sediments overlie typically coarser-textured materials. Depth to bedrock is from 20 to 100 feet. Permeability is moderate to moderately slow. Foundation support is typically adequate for small buildings (three stories or less). Suitability for septic drainfields and infiltration trenches may be marginal because of slow permeability.

(89) Tidal Marsh
Tidal marsh areas occur along the Potomac River and are periodically inundated by flood waters under tidal influence4. The soils consist of organic-rich, highly-stratified sandy, silty and clayey sediments. Underlying soil is usually soft. Floodwater from tidal inundation are typically shallow. Plant communities consist of sedges, cattails and other hydrophytic plants.

(90) Augusta fine sandy loam
This predominantly sandy and silty soil occurs on stream terraces in the Piedmont Upland and Coastal Plain. On low terraces along larger streams, the soil may be subject to flooding1. A dense sandy clay subsurface layer, 1 to 1.5 feet thick, is often found 1.5 feet below the surface. A perched seasonal high water table occurs above the dense layer, one to two feet below the surface. Depth to hard bedrock is from 10 to 60 feet. Permeability is moderately slow. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are necessary to prevent wet basements. Grading and subsurface drainage is required to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of slow permeability, perched water table, and potential flooding.

(91) Birdsboro
This soil, occurring on low terraces along Bull Run and Cub Run, consists of predominantly silty and clayey alluvium. Low areas are within the floodplain1. The seasonal high water table is two to four feet below the surface. Depth to red shale or sandstone bedrock is generally from 7 to 20 feet, but may be within 2 feet in some places. Permeability is moderately slow. Foundation support may be poor because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are needed to prevent wet basements. Grading and subsurface drainage are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor due to the water table and potential flooding. Use of the bedrock as engineered fill, road embankment, or trench backfill is limited due to rapid disintegration.

(92) Raritan
This soil, occurring on low terraces along Bull Run and Cub Run, consists of predominantly silty and clayey alluvium. Low areas are within the floodplain1. The seasonal high water table is 0.5 to 3 feet below the surface. Depth to red shale or sandstone bedrock is generally from 7 to 20 feet, but may be within 2 feet in some places. Permeability is moderately slow. Foundation support may be poor because of soft soil and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Engineered drainage is often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor due to the water table and potential flooding. Use of the bedrock as engineered fill, road embankment, or trench backfill is limited due to rapid disintegration.

(104) Catlett
This silty and gravelly soil occurs on hilltops and sideslopes underlain by gray baked sandstone and shale. Hard bedrock is generally within two feet of the surface. Soil permeability is moderate, but drainage may be restricted by hard bedrock. Foundation support is generally good. Grading and subsurface drainage may be needed to prevent wet yards. Suitability for septic drainfields and infiltration trenches is poor because of shallow bedrock. Use of this bedrock as engineered fill, road embankment, or trench backfill is limited due to rapid weathering. Added topsoil may be needed in shallow areas to provide adequate rooting depths for lawns, trees, and landscape plants.

(110) Augusta loam
This predominantly silty soil occurs on stream terraces in the Piedmont Upland and Coastal Plain. On low terraces along larger streams, the soil may be subject to flooding1. A dense silty clay subsurface layer, 1 to 1.5 feet thick, is often found 1.5 feet below the surface. A perched seasonal high water table occurs above the dense layer, one to two feet below the surface. Depth to hard bedrock is from 10 to 60 feet. Permeability is moderately slow. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are necessary to prevent wet basements. Grading and subsurface drainage is required to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of slow permeability, perched water table, and potential flooding.

(112) Augusta sandy loam
This predominantly sandy and silty soil occurs on stream terraces in the Piedmont Upland and Coastal Plain. On low terraces along larger streams, the soil may be subject to flooding1. A dense sandy clay subsurface layer, 1 to 1.5 feet thick, is often found 1.5 feet below the surface. A perched seasonal high water table occurs above the dense layer, one to two feet below the surface. Depth to hard bedrock is from 10 to 60 feet. Permeability is moderately slow. Foundation support may be marginal because of soft soil and seasonal saturation. Foundation drains (exterior and interior) and waterproofing are necessary to prevent wet basements. Grading and subsurface drainage is required to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of slow permeability, perched water table, and potential flooding.

(113) Fairfax gravelly silt loam
This upland soil consists of silty and gravelly old alluvium, typically 3 to 7 feet thick, overlying silty and sandy decomposed rock. A discontinuous dense layer results in a "perched" seasonal water table at 1.5 to 2.5 feet below the surface. Depth to rock is from 10 to 100 feet. Permeability is moderately slow in the dense layer and moderate in the underlying soils. With adequate engineered drainage, the soil typically provides adequate support for small buildings (3 stories or less). Exterior foundation drains and waterproofing are necessary to prevent wet basements and crawl spaces. Surface grading and subsurface drains may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is marginal because of slow permeability and the perched water table.

(114) Masada fine sandy loam
Masada is found on high terraces, formed in loamy and gravelly material washed from soils of the Piedmont Upland. The sticky, plastic clay subsoil may restrict drainage and be difficult to manipulate for engineering purposes when wet. Depth to hard bedrock ranges from 30 to 150 feet. Permeability is moderately slow in the subsoil. Foundation support is typically good. Exterior foundation drains and waterproofing are needed to prevent wet basements. Grading and subsurface drainage are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is marginal because of slow permeability.

(115) Hiwassee fine sandy loam
This soil occurs on high stream terraces in the Piedmont Upland and Coastal Plain. Flooding may occur following severe storm events1. Fine sandy, silty and clayey sediments are underlain with coarser textured materials. Depth to bedrock is from 20 to 100 feet. Permeability is moderate to moderately slow. Foundation support is typically adequate for small buildings (three stories or less). Suitability for septic drainfields and infiltration trenches may be marginal because of slow permeability.

(116) Christiana
This soil occurs on hilltops and sideslopes in the Coastal Plain. Red plastic clays and silty clays may contain thin sandy strata. Depth to bedrock is greater than 30 feet. Subsurface permeability is moderately slow to slow, often resulting in a perched water table at variable depths. Foundation support is marginal because of the plastic clays. Foundation drains and waterproofing are necessary to prevent wet basements. Grading and subsurface drainage are often necessary to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of the clay and slow permeability. Christiana is similar to the Marine Clays.

(117) Fresh Water Marsh
This soil occurs in low, flat areas in the Coastal Plain and is periodically wet, inundated, or partially submerged by fresh water. Flooding may occur following storm events1. An organic surface covers highly variable, stratified sandy, silty and clayey sediments. The seasonal high water table may be at or above the surface for extended periods of time. Permeability is generally low. Foundation support is poor because of soft and very soft soil and seasonal saturation. Basements below existing grade are not recommended because of potential severe wetness problems. Septic drainfields and infiltration trenches are poorly suited because of wetness and potential flooding. Sedges, cattails and other hydrophytic plants are predominant. Fresh water marshes are largely wetland areas2.

(118) Marine Clay
This unit occurs on hilltops and sideslopes in the Coastal Plain. Highly plastic silts and clays of variable thickness underlie surface silts to gravels a few inches to a few feet thick. The clay deposits consist of highly fractured and broken clays and silty clays which have a high shrink-swell potential. The depth of the seasonal high water table is variable depending on soil stratification, landscape position, and local hydrologic features such as seepage areas. Water is often perched above slowly permeable subsurface strata. Depth to hard bedrock is generally greater than 50 feet. Slope instability and poor foundation support are major problems requiring intensive geotechnical analysis. Numerous structures have sustained damage from inadequate construction practices. Septic drainfields and infiltration trenches are poorly suited because of plastic clays, perched water table, and unstable slopes.

(120) Altavista
This clayey soil occurs on low stream terraces in the Coastal Plain. Flooding may occur following storm events1. The clayey subsoil restricts drainage, resulting in a perched seasonal high water table within two to three feet of the surface. Depth to hard bedrock is 10 to 40 feet. Permeability is moderately slow. Foundation support is typically good with proper drainage. Foundation drains and waterproofing are needed to prevent wet basements. Grading and subsurface drainage are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the water table, slow permeability, and potential flooding.

(128, 129) Montalto stony/rocky silt loam
This upland soil consists of a silty surface and a clayey subsoil underlain by a diorite/diabase bedrock. Surface stones and occasional rock outcrops may be present. Depth to bedrock ranges from two to six feet. Permeability is moderate. These soils generally occur in association with the highly plastic Iredell soils. Montalto soils have a lower plasticity than Iredell, and are generally suitable for building support. Suitability for septic drainfields and infiltration trenches is marginal to poor because of the shallow depth to rock.

(132) Mayodan
This soil occurs on hilltops and sideslopes along the eastern edge of the Triassic Basin. Bedrock consists of relatively thin deposits (2 to 10 feet) of sandstone conglomerates mixed with schist materials. The loamy surface and silty clay to clay subsurface contains rounded and angular gravel. Depth to rock is from 10 to 15 feet. A moderately slow to slow subsoil permeability may result in saturated surface soils and a perched seasonal water table for short duration following rainfall events. Foundation support for small buildings (3 stories or less) is generally favorable. Exterior foundation drains and waterproofing are necessary to prevent wet basements and crawl spaces. Grading and subsurface drains may be needed to eliminate wet yards. Shallow bedrock in some areas may limit the suitability for septic drainfields and infiltration trenches.

(141) Rocky Land - (Orange)
This mapping unit occurs on hilltops and sideslopes in association with the Orange soils in the greenstone areas. Frequent rock outcrops or boulders cover 20 to 50 percent of the surface. Plastic clay subsoils may occur at one to three feet. The depth to hard bedrock varies from zero to 15 feet. The depth to seasonal high water table varies from one to greater than ten feet. Foundation support is good on bedrock, but may be poor in areas with plastic clay subsoil. Suitability for septic drainfields and infiltration trenches is poor because of plastic clays and shallow depth to rock. The shallow bedrock and stoniness make these soils difficult to excavate and grade. Blasting in the hard bedrock may be required for below grade basements and excavations. The greenstone bedrock may contain naturally occurring fibrous asbestos minerals3. These fibers may become airborne during excavation and blasting operations. Worker protection and dust control measures are required in such instances.

(142) Very Rocky Land - (Orange)
This mapping unit occurs on hilltops and sideslopes in association with the Orange soils in the greenstone areas. Frequent rock outcrops or boulders cover over 50 percent of the surface. Plastic clay subsoils may occur at one to three feet. The depth to hard bedrock varies from zero to 15 feet. The depth to seasonal high water table varies from one to greater than ten feet. Foundation support is good on bedrock, but may be poor in areas with plastic clay subsoil. Suitability for septic drainfields and infiltration trenches is poor because of plastic clays and shallow depth to rock. The shallow bedrock and stoniness make these soils difficult to excavate and grade. Blasting in the hard bedrock may be required for below grade basements and excavations. The greenstone bedrock may contain naturally occurring fibrous asbestos minerals3. These fibers may become airborne during excavation and blasting operations. Worker protection and dust control measures are required in such instances.

(148) Iredell-Mecklenburg
This highly plastic soil occurs on hilltops and sideslopes, formed in weathered diabase materials. A silty surface overlies a sticky plastic clay subsoil one to three feet thick. Sandy clays and clayey sands occur below the clay layer. A perched seasonal high water table, above the clays, is one to two feet below the surface. Depth to hard bedrock is usually from 3 to 15 feet. Permeability is slow. Foundation footings must extend below the soft plastic clays, generally to bedrock, to ensure competent building support. Foundation drains, surface grading, and waterproofing are necessary to prevent wet basements and crawl spaces. Surface grading and subsurface drainage may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of the plastic clays, perched water table, and shallow depth to bedrock. Deep basements and excavations may require blasting in hard bedrock.

(149) Lunt
The Lunt series is an extremely variable unit found on hilltops and sideslopes in sands, silts, and clays of the Coastal Plain. A silty surface overlies plastic silty and clayey subsoils. The subsoil is slowly permeable, resulting in a perched seasonal water table. Depth the hard bedrock is typically greater than 75 feet. The 149 unit, usually in close proximity to areas of the Marine Clay, should be analyzed for foundation support and slope stability. Foundation drains, surface grading, and waterproofing are necessary to prevent wet basements and crawl spaces. Suitability for septic drainfields and infiltration trenches is poor because of the slowly permeable clays and potential slope instability.

(152) Elbert - (Orange Group)
This wet, plastic soil occurs in drainageways and footslopes in materials derived from weathered greenstone and alluvium. Slowly permeable plastic clay subsoils occur 2 to 4 feet below the surface. The seasonal high water table is 0 to 0.5 foot below the surface. The depth to bedrock varies from 3 to 15 feet. Foundation footings must extend below the soft plastic clays, generally to bedrock, to ensure competent building support. Basements below existing grade are not recommended because of potential severe wetness problems. Engineered drainage designs are often required to eliminate wet yards. Septic drainfields and infiltration trenches are poorly suited because of wetness, plastic clays and shallow depth to bedrock. Elbert is predominantly hydric and may contain potential nontidal wetlands2. The greenstone bedrock may contain naturally occurring fibrous asbestos minerals3. These fibers may become airborne during excavation and blasting operations. Worker protection and dust control measures are required in such instances.

(232) Fairfax loam
This upland soil consists of silty, clayey and gravelly old alluvium, typically 3 to 7 feet thick, overlying silty and sandy decomposed rock. A discontinuous dense layer results in a "perched" seasonal water table at 1.5 to 2.5 feet below the surface. Depth to rock is from 10 to 100 feet. Permeability is moderately slow in the subsurface. Building support may be marginal because of soft soil and seasonal saturation. Foundation drains (interior and exterior) and waterproofing are necessary to prevent wet basements and crawl spaces. Surface grading and subsurface drains may be needed to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is marginal to poor because of slow permeability and the perched water table.

(273) Readington
This silty and clayey soil occurs on nearly level uplands underlain by red shale and sandstone. The seasonal high water table, perched above bedrock, is 0.5 to 2 feet below the surface. The depth to bedrock is from two to three feet. Soil permeability is moderate, but the shallow bedrock has few fractures to allow water to pass through. Foundations typically extend to shallow rock. Foundation drains and waterproofing are necessary to prevent wet basements. Grading and subsurface drainage are often required to eliminate wet yards. Suitability for septic drainfields and infiltration trenches is poor because of shallow bedrock and the perched water table. Use of this bedrock as engineered fill, road embankment, and/or trench backfill is limited due to rapid disintegration. Added topsoil may be needed to provide adequate rooting depths for lawns, trees, and landscape plants.


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