Environmental Constraints

• View Map 3: Soils
• View Map 4: Environmental Constraints

The combination of slopes, soil types and flood prone areas create severe development constraints in several areas of the Northeast Knox County Sector.

Geology
The geology of the northeast Knox County is typical of the Tennessee Valley, a complex pattern of layers of sedimentary rock running in narrow, parallel bands from southwest to northeast. Softer layers of limestone and dolomite (carbonate) weathered away to form valleys, leaving behind harder shale and sandstone as hills and ridges. Approximately 40 percent of the sector is underlain by carbonate bedrock, which contains sinkholes, caverns, and underground solution channels. Chronic drainage problems can exist in these areas because of the amount of surface runoff collected by the system. Careful subsurface analysis and site planning is necessary.

Slopes
House Mountain is the most prominent topographic feature in the sector. Rising over 2,100 feet, it is the highest point in Knox County. Copper Ridge, Beaver Ridge, McAnnally Ridge and Black Oak Ridge are dominant as well, each rising over 1,400 feet.

House Mountain, the highest point in Knox County, is surrounded by agricultural land.

Soils
Nine soil resource areas have been identified in the sector, with most having limitations for development. Dewey-Decatur and Fullerton-Dewey, the two types most suited for development, are also prime soils for agricultural uses. The major area containing these soils is along the Holston River.

The area has an abundance of Litz-Sequoia soil, which is rated as moderate for most types of development. The soil’s main negative characteristic is poor percolation, with the risk of potential failure of septic systems. The soils are described in Table 3 and shown on Map 3.

Table 3: Soil Resource Areas

• Fullerton-Clarksville: Deep cherty or gravelly soils on hilly-to-steep topography. Generally have severe limitations for development due to steep slopes.
• Talbot-Rock Outcrop: Shallow and moderately deep, rolling to hilly, clayey soils. Limestone rock, outcrops are numerous. Slow percolation.
• Muskingum-Lehew: Shallow and moderately deep, steep, loamy and stony soil on sandstone ridges. Subject to erosion and very steep.
• Dewey-Decatur: Deep, gently rolling to rolling, well-drained, clayey soils on productive land underlain by dolomite. Percolation generally good.
• Litz-Sequoia: Shallow and moderately deep, rolling to steep, shaly and clayey soils on hills. Slow percolation because of shallow bedrock.
• Tellico-Alcoa: Deep, steep hills and ridges, well-drained, red loamy soils underlain by sandstone and or sandy shale bedrock. Steep slopes cause severe limitations.
• Dandridge-Sequoia: Shallow soil consisting of silt loam on the surface and shaly, silty clay loam in subsoil. Predominately more than 20% slope. Very steep and very poor percolation.
• Fullerton-Dewey: Deep, rolling to hilly, well-drained clayey soils underlain by dolomite. Percolation generally satisfactory.
• Huntington-Linside-Melvin: Deep, nearly level, well-drained to poorly-drained soils on floodplains and terraces of major streams. (Source: U.S. Department of Agriculture, Soil Conservation Service, Soil Features and Limitations for Selected Land Uses in Knox County, Tennessee, 1972.)

Hydrology
Most of the runoff from this sector flows to the Holston River, carried primarily by Big Flat, Little Flat, Loves and Roseberry Creeks. Beaver Creek runs to Melton Hill Lake. Streams and their 500 year floodplains are depicted on Map 4.

Preliminary floodway mapping for several streams, including Beaver Creek and Flat Creek, is now available. Although it could be several months before the official adoption process by the Federal Emergency Management Agency (FEMA) is complete, the new data is more accurate than previous information and it is included in this report. Many parts of northeast Knox County were so rural in the 1970’s when FEMA prepared the first flood hazard maps, no mapping was completed in those areas.

Sinkholes are the drainage outlets for significant portions of the limestone areas of the sector. Intense land development in areas drained by sinkholes is a concern because vegetation is removed and replaced with impervious surfaces, including buildings, roads and parking lots. Infiltration is reduced and runoff increases. This is of particular concern in outlying areas with no stormwater drainage infrastructure, because sinkholes may be the only outlets. When water tables are high and there is prolonged rain, flooding can result.

Areas which have sinkholes that are subject to flooding are also shown in Map 4.

Groundwater contamination is another problem associated with development near sinkholes. When sinkholes are used as dumps, the contaminants can go directly into the groundwater system.

Flood prone areas such as Big Flat Creek near E. Emory Road are difficult to develop.

Protecting the headwaters of Loves Creek will help maintain and improve overall water quality.