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PRS Erosion Matrix Score Assessment Date Structure Mesa Top Bench Canyon Floor Channel Topography Explanation Ground Explanation Slope Explanation Runoff Evidence Channelized Channel Description Runoff Wetland Runoff Other Terminus Explanation Runoff Explanation Structure Run-On Structure Explanation NPDES Run-On NPDES Explanation Natural Run-On Natural Run-On Explanation ESH-18 Representative BMP Prescription BMP Description Not BMPs Sediment Comments
50-004(a) 38.6 7/6/1999 50-66 YES NO NO NO Former industrial waste line at TA-50 removed in 1975. Concrete enclosed. Flat area within TA-50 Complex YES NO Runoff from surrounding area through series of catch basins and culverts.     Runoff from TA-50 discharges directly into canyon.  No exposure to contaminants (removed and subsurface). None observed. YES Surrounding buildings and parking lots. YES Active operations ongoing at TA-50. NO Local Veenis, Steve     NO PRS removed and subsurface.
50-004(b) 38.6 7/6/1999 50-66 YES NO NO NO Underground stainless steel-lined concrete tanks.  Tanks removed in 1989. Concrete enclosed. Flat area within TA-50 Complex YES NO Runoff from surrounding area through series of catch basins and culverts.     Runoff from TA-50 discharges directly into canyon.  No exposure to contaminants (removed and subsurface). None observed. YES Surrounding buildings and parking lots. YES Active operations ongoing at TA-50. NO Local Veenis, Steve     NO PRS removed and subsurface.
50-006(a) 77.8 9/4/1997 50-83 NO NO NO YES PRS is watercourse in Ten Site canyon. Heavy ground and canopy cover along edges of channel.  Little to no vegetation within channel. Bottom of Ten Site canyon. YES YES PRS is a portion of the natural channel within Ten Site canyon.       Erosion formed and continues to shape the watercourse in the canyon bottom. YES Structures and asphalt surfaces in TA-50 and TA-35 contribute run-on to Ten Site canyon. NO   YES This area is a natural drainage. T. Lemke   Removed contaminated soil, straw bales placed on down-slope side. BMPs installed 11/30/96 NO Located within the watercourse of a natural drainage; erosion potential exists.
50-006(c) 38.6 7/6/1999   YES NO NO NO 50-006(c) air emissions from TA-50, 50-007 incinerator complex (50-37) not operating, 50-008 Volume Reduction Facility (50-69) not operating. Asphalt/Building coverage Flat throughout TA-50 Complex. YES NO Runoff through series of catch basins and culverts at TA-50     Runoff from all of TA-50 discharges directly into canyon. No erosion observed within TA-50 Complex. YES Surrounding buildings and parking lots. YES Active ongoing operations. NO Local run-on Veenis, Steve     NO Potential impact to Tensite Canyon due to velocity of runoff from TA-50.  Source of contamination has been removed and is subsurface.
50-006(d) 89.0 7/31/1998 35-213 NO NO NO YES Outfall from radioactive liquid waste treatment plant into Mortandad Canyon.  Outfall located within TA-35, at bottom of dirt access road, about 50-75 feet west of green 6 inch gas line. Channel is bare, exposed tuff.  Surrounding area has sparse vegetation with some pine tree cover. Channel slope gradual.  Surrounding area south of PRS where the discharge formerly outlet, slopes sharply to main drainage. YES YES Main watercourse on Mortandad Canyon.     Outfalls directly into watercourse. South of PRS, at former outfall location there is rill erosion leading to the watercourse. NO No direct impact.  Indirect from all facilities draining to Mortandad Canyon. YES PRS is NPDES outfall EPA 051051. YES PRS located at natural bottom of slopes into Mortandad Canyon. D. Mays Install BMPs on slope south of PRS to prevent transport of sediments potentially contaminated from historical outfall operations, as evidence by rill formation.  Recommend run-on diversion dike, reseeding and/or jute mat.   NO  
50-007 38.6 7/6/1999 50-37 YES NO NO NO 50-006(c) air emissions from TA-50, 50-007 incinerator complex (50-37) not operating, 50-008 Volume Reduction Facility (50-69) not operating. Asphalt/Building coverage Flat throughout TA-50 Complex. YES NO Runoff through series of catch basins and culverts at TA-50     Runoff from all of TA-50 discharges directly into canyon. No erosion observed within TA-50 Complex. YES Surrounding buildings and parking lots. YES Active ongoing operations. NO Local run-on Veenis, Steve     NO Potential impact to Tensite Canyon due to velocity of runoff from TA-50.  Source of contamination has been removed and is subsurface.
50-008 38.6 7/6/1999 50-69 YES NO NO NO 50-006(c) air emissions from TA-50, 50-007 incinerator complex (50-37) not operating, 50-008 Volume Reduction Facility (50-69) not operating. Asphalt/Building coverage Flat throughout TA-50 Complex. YES NO Runoff through series of catch basins and culverts at TA-50     Runoff from all of TA-50 discharges directly into canyon. No erosion observed within TA-50 Complex. YES Surrounding buildings and parking lots. YES Active ongoing operations. NO Local run-on Veenis, Steve     NO Potential impact to Tensite Canyon due to velocity of runoff from TA-50.  Source of contamination has been removed and is subsurface.
50-009 54.8 10/30/1997 50-1 YES NO NO NO MDA C located on the mesa top on the south side of Ten Site canyon near TA-50. Significant ground cover consisting of various types of brush and grasses.  Minimal  canopy cover along the north/eastern fence line.. Gently slopes towards the north towards Ten Site Canyon. YES YES Sheet flow runoff evidence along the eastern fence line towards the east.  Along the northern fence line a man-made channel asphalt/volcanic tuff-lined channel and  has eroded into existing soils. The channel has moved soils off site and into canyon.     The headwaters of Ten Site Canyon are located less than 50 meters from the northern fence line of MDA C.  Sheetflow runoff and discharges from the erosional feature go directly into the Canyon. Evidence of sheetflow erosion exist around the east/northeast part of site.  Gully erosion exists along the northern fence line and crosses under fence and into Ten Site Canyon. NO No structures within the immediate proximity of MDA C. NO No operational impacts. NO No upslope drainage impacts. Veenis, Steve     NO Flow dissipation within channel and sediment migration controls are needed.
50-011(a) 38.6 7/6/1999 50-83 YES NO NO NO Former septic system and associated leach field (removed 1983). Asphalt coverage on most of area.  Grasses/weeds on the East facing slope. Mostly flat at former leach field and septic tank locations. YES NO Runoff flows into asphalt lined channels north and south of site into Ten Site Canyon.  East facing slope flows into large gully.     Local runoff discharges directly into Ten Site Canyon. None observed since asphalt covered. YES Buildings, roof drains, parking lots create run-on to site. YES Active operations throughout the eastern portion of TA-50 Complex. NO None. Veenis, Steve   Asphalt channels, riprap lined conveyance nearby. NO Runoff into large gully east of site contributing to erosion problem, but not from PRS (subsurface/removed)