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HomeMy WebLinkAboutSUB200800206 Review Comments Groundwater Assessment 2008-08-29Tier II Groundwater Assessment TMP 70 -14 Application Number: SUB200800206 Tiverton Farm LLC (Lot A) - Rural Groundwater Reviewer: J. Rubinstein Date: 29 August 2008 Description: 1 division — 2 lots Water Quantity The Albemarle County Database shows 40 wells within half a mile of the lot. The wells range from 28 to 775 feet in depth with a median depth of 165 feet. The well yields range from 0 to 60 gallons per minute with a median yield of 5 gallons per minute. Water Quality As shown on the Virginia Department of Environmental Quality (DEQ) GIS website, there are two leaking underground storage tank sites (LUST) on tax map 70 — 14 of which one is on Lot 1.1 Therefore Section 500 through 503 of Albemarle County Code requires that the well be tested for the volatile organic compounds Benzene, Toluene, Ethylbenzene and Xylenes before a building permit can be issued. 2 Buffers According to the Albemarle County GIS site and as shown on the plat, a buffer is required by the Water Protection Ordinance along the southern boundary of Lot 2.3 The parcel is in the Stockton Creek Watershed which is a portion of the watershed for the South Fork Rivanna Reservoir, a public water supply. It is not within the reservoir's buffer. Site Description According to the Virginia Department of Mineral Resources 1993 Map, most of the parcel is in the mylonite of the Blue Ridge Basement Complex 1 http: // gisweb. deq .virginia.gov /deqims /viewer.htm ?SERVICE= VA_DEQ 2 http: / /www.albemarle.org /department. asp ?department= ctyatty &relpage =2784 3 http: / /gisweb.albemarle.org/ (my). Gneiss (Ybg) and pyroxene granulite (Ypg) of the same formation also occurs on the property. In a groundwater assessment done for the Albemarle County, ENSAT Corporation divided the county into `hydrologic units'. Below is ENSAT's description of the unit containing most of the parcel: The Colluvial Fan unit lies at the base of the eastern slopes of the Blue Ridge Mountain and is characterized by relative steep drainage swales that extend to more gradual sloping conditions. The area includes a series of intermittent drainages that include ephemeral drainage ways. Many of the intermittent drainages become perennial streams as this area includes stream bottom valleys. A significant portion of the unit area consists of transported soils including the Braddock and Thurmont. These soils are formed in colluvial and alluvial materials found on colluvial fans and terraces and are the product of weathered granite, granodiorite, granite gneiss, and greenstone. Both of these soil series are deep and well drained with slopes ranging from 2 -25 %. Residual soils including the Hayesville and the Chester are also abundant. These soils are also deep and well drained and are formed on upland slopes from weathered products of granite and granite gneiss. Slopes of these soils typically range from 2 -45 %. The accumulation of transported soils (colluvial and alluvial) can form "cappings" over residual soils and parent material, which can add to the overall thickness of the overburden. The hydrologic unit for the southern portion of the property is described as: The Piedmont Foothills unit is characterized by rolling upland to relatively steep topography. Soils within this area re dominated by the Hayesville, Ashe and Chester soil series which are moderately deep to deep, and generally well drained. These soils are found on the piedmont upland and foothills of the Blue Ridge Mountain on slopes ranging from 2-45%.