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Home My WebLink AboutSUB201700069 Groundwater Assessment 2017-07-12TIER II GROUNDWATER ASSESSMENT County of Albemarle Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia 22902 434-296-5832 1 www.albemarle.org/cdd Water Quantity Water Quality Hydrography Geology Tier II Groundwater Assessment Site Map 0 100 200 300Feet APP#: SUB 2017-00069 Q Subject Parcel 0 LUSTs TM P: 09400-00-00-024AO ❑ Known Water Wells 0 Superfund Sites �r ❑Map Created by CDD on: 06/15/2017 Water Protection Landfills ***Aerial Imagery from Y2013*** Ordinance Buffers 2 *Hydrogeologic Units Defined Taken from the 1213012003 Albemarle County Hydrogeologic Assessment Phase II — Groundwater Availability and Sensitivity Assessment with Proposed Groundwater Assessment Standards. Prepared by ENSAT Corporation, Culpeper, VA. The process of investigating groundwater availability at the County -wide scale involved identifying distinct hydrogeologic units and comparing the units based on groundwater availability characteristics for which data could be obtained. Each hydrogeologic unit shares some common characteristics with regard to geology, soils, and topography, although there is quite a bit of variability within each unit. Nine hydrogeologic units were identified across the County, as follows, and as shown on the Albemarle County Hydrogeologic Unit Map (Figure 2). 2. Figure 2 - Albemarle County Hydrogeologic Unit Map Blue Ridge West-IW: This unit lies primarily on the steep eastern slopes of the Blue Ridge Mountains and is dominated by the Myersville and Parker Soils, and to a lesser extent the Chester. Slopes range from 2-60%. These soils are residual in nature. The Myersville soils are derived from weathered volcanic metamorphic rocks (greenstone) and Parker and Chester soil series are derived from weathered granite and granite gneiss. These soils are considered to be relatively deep and well drained. Blue Ridge East-IE: The Blue Ridge East unit overlies volcanic greenstone rock and represents the eastern limb of the Blue Ridge Anticlinorium. The area is characterized by the presence of a prominent ridge and trends generally northeast within the otherwise rolling piedmont landscape. Portions of this ridge are known locally as Green Mountain, Carters Mountain, and the Southwest Mountains. This area is dominated by the Rabun and Myersville soils and to a lesser extent, the Catoctin. The Rabun soil series is deep and well drained and like the Myersville soil series is formed from weathered greenstone. The Catoctin soil series is considered to be moderately deep and well drained and is also formed from weathered greenstone. Colluvial Fans -II: The Colluvial Fan unit lies at the base of the eastern slopes of the Blue Ridge Mountain and is characterized by relatively 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%. Bedrock geology consists largely of metagranitic rock of the Blue Ridge Basement Complex and metasedimentary, metaconglomerate and phyllite of the Swift Run Formation. 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. 4. Piedmont Foothills -III: The Piedmont Foothills unit is characterized by rolling upland to relatively steep topography. Soils within this area 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%. These soils are formed 3 from weathered granites and meta -granites of the Blue Ridge Basement complex. The Piedmont Foothills area is bifurcated by Hydrogeologic Unit IV (Lynchburg). Lynchburg -IV: The Lynchburg unit is characterized by a relatively narrow band that trends in a northeast direction and includes a relatively long segment of the Mechums River valley. Soils within this unit are dominated by the Hazel and to a lesser extent by the Elioak and Glenelg soils. The Hazel soil series are moderately deep and well drained and are formed in the weathered products of metagraywacke sandstone and mica schist. Hazel soils lie on uplands and their slopes range from 7- 45%. The Elioak soil series are deep and well drained and are formed in the products of weathered micaeous metamorphic rock. Slopes of the Elioak range from 2-25%. The Glenelg soils are also deep and well drained and are formed in the weathered products of quartz mica schist. Slopes of the Glenelg range from 2-45%. The area is underlain primarily by the Lynchburg Formation and/or the Mechums River Formation which consists largely of metagraywacke, meta sandstone, and graphitic schist. Ragged Mountain-V: The Ragged Mountain unit is characterized by mountainous terrain located in the southwestern portion of the County and is underlain by the metagranitic rocks of the Blue Ridge Basement Complex. The soils in the area are dominated by the Chester, Hayesville, Ashe, and Parker soil series. These soils are derived from weathered granite and granite gneiss and are deep and excessively well drained. These soils range in slope from 2-45% with some slopes up to 60 percent in the Parker soils. Candler -VI: The Candler unit is underlain primarily by the Candler formation. Bedrock geology includes phyllites and to a lesser degree laminated metasiltstone. Soils underlying the unit area are dominated by the Manteo and Nason series. Manteo soils are shallow and somewhat excessively drained. The Manteo soils are formed in the weathered products of sericitic schist/phyllite on uplands and range in slope from 2-45%. The Nason soil series are deep and well drained and are also formed in the weathered products of sericitic schist/phyllite. The Nason soils are formed on uplands and range in slope from 2-25%. Newark Basin-VII: The Newark Basin unit is characterized by low relief topography, which exists over Mesozoic basin geology. The unit is underlain by the Newark Supergroup which consists of sandstones, siltstones, and shales. Soils within this area are dominated by the Totier, Rapidan, and Penn series. The Totier soil series are deep and well drained and are formed from weathered Triassic red shale. These soils are found on uplands and range in slope from 2-15% deep to moderately deep and well drained. Slopes range from 2-25%. The Rapidan soil series are also deep and well drained and are formed in weathered products of Triassic conglomerate. The Rapidan, like the Totier, are found on uplands and range in slope from 2-25%. The Penn series are moderately deep and well drained and are formed from the weathered products of Triassic red shale. The Newark Basin hydrogeologic unit includes the Scottsville Basin located in the southern portion of the County and much smaller area of the Barboursville Basin located in the northern portion of the County. 9. Piedmont Proper-VIII: The Piedmont Proper unit is characterized by gently rolling piedmont topography. The bedrock geology underlying the unit is mapped as Metagraywacke, quartoze schist, and melange. Soils in the unit area are dominated by the Nason and the Manteo in nearly equal percentages. Although these same soils also dominated the Candler unit, it should be noted that the Manteo soils were nearly twice as prevalent as compared to the Nason. Manteo soils are shallow and somewhat excessively drained. The Manteo soils are formed in the weathered products of sericitic schists/phyllites on uplands and range in slope from 2-45%. The Nason soil series are deep and well drained and are also formed in the weathered products of sericitic schist. The Nason soils are formed on uplands and range in slope from 2-25%. 10. Barboursville -IX: This unit exists in only a small portion of the County at the area where Route 20 enters Orange County. Evidently this hydrogeologic unit was small enough that it did not factor into the ENSAT report and therefore does not have a description like the other units. You can see an unlabeled delineation of this unit in the map (Figure 2) along the northern County boundary near the right-hand side. M