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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
53-001(a) 10.6 6/18/1999 53-2 YES NO NO NO Drum storage area with secondary containment and cover.  Also area east of existing storage area where discharges occurred. Concrete curbed structure. Flat area surrounding existing pad. NO NO Some ponding nearby, but no evidence of runoff.       None observed. YES Parking lot next to site creates sheetflow run-on. NO No operational impact. YES Hillslope north of site creates run-on to site (some rills on hillslope). Veenis, Steve   Curbed concrete containment with propanel roof. NO  
53-001(g) 3.6 7/31/1998 53-1031 YES NO NO NO "High Radiation Area" storage contained within 15 foot deep cut into tuff, located southeast of Building 53-30, northwest of "Boneyard" PRS 53-010. Area within 15 foot high tuff walls is paved with asphalt. Flat. NO NO           NO   NO   NO   D. Mays   On west side of storage area, atop the 15 foot high tuff wall, is a diversion channel, also carved into the tuff, to divert storm water run-on.  Channel 4-5 feet deep. NO Due to access restrictions to this PRS this assessment was completed from outside the fence on the south boundary.
53-002(a) 47.8 10/29/1997   YES NO NO NO Located between Sandia and Los Alamos canyons.  NPDES outfall from lagoons at TA-53.  Outfall at east end of lagoons. Riprap extends from base of the outfall to a culvert under the roadway. Sparse ground cover extends from the culvert, across the mesa top, to the canyon edge. Lagoons are located on flat area. YES NO Lagoons are dry and the outfall is not active.  However, there is evidence of discharge (erosion) from the culvert under the roadway.  This area is within the PRS boundary.      Outfall discharged directly into canyon. Adjacent to the NPDES outfall, a culvert is placed under the roadway.  This culvert conveys storm water as well as discharges from the outfall.  Minor rill erosion is present at the culvert outlet. NO   YES Site is not active but is still classified as active NPDES outfall EPASSS095. NO   T. Lemke   Riprap extends from the NPDES outfall to the inlet of the culvert under the adjacent roadway. NO Outfall is no longer active.  Area is relatively flat so only a minimal amount of storm water would flow across the site.

Outfall is a concrete flume with a metal wire.
53-002(b) 3.6 10/29/1997   YES NO NO NO Active lagoon located on mesa top between Sandia and Los Alamos canyons.  Located south of lagoons classified as PRS 53-002(a). Sides and bottom of lagoon are covered with an impermeable membrane.   NO NO Lagoon is situated below grade.  An overflow outlet that discharges to the same outfall as 53-002(a) is located within the lagoon.         NO   NO   NO   T. Lemke     NO Contents of lagoon are contained.  The current liquid level in the lagoon is much lower than the overflow outlet.
53-006(a) 3.6 7/31/1998 53-3M YES NO NO NO One steel and one concrete underground storage tank located at southwest corner of Building 53-3M.  Surrounded by pavement on all sides. 100% pavement cover. Flat. NO NO           NO Top of tanks elevated about 18 inches from surrounding pavement. NO   NO   D. Mays     NO  
53-006(b) 3.6 7/31/1998 53-3M YES NO NO NO One steel and one concrete underground storage tank located at southwest corner of Building 53-3M.  Surrounded by pavement on all sides. 100% pavement cover. Flat. NO NO           NO Top of tanks elevated about 18 inches from surrounding pavement. NO   NO   D. Mays     NO  
53-006(c) 3.6 7/31/1998 53-3M YES NO NO NO One steel and one concrete underground storage tank located at southwest corner of Building 53-3M.  Surrounded by pavement on all sides. 100% pavement cover. Flat. NO NO           NO Top of tanks elevated about 18 inches from surrounding pavement. NO   NO   D. Mays     NO  
53-006(d) 3.6 7/31/1998 53-30 YES NO NO NO One steel and one concrete underground tank located in paved area between Building 53-16 and Building 53-30. 100% asphalt cover. flat. NO NO           NO Tanks sealed underground. NO   NO   D. Mays     NO  
53-006(e) 3.6 7/31/1998 53-30 YES NO NO NO One steel and one concrete underground tank located in paved area between Building 53-16 and Building 53-30. 100% asphalt cover. flat. NO NO           NO Tanks sealed underground. NO   NO   D. Mays     NO  
53-006(f) 3.6 7/31/1998 53-1 YES NO NO NO Underground storage tank just east of stack at northeast corner of Building 53-1. Tank contained asphalt top. Tank contained surrounding area drains to channel east of Building 53-1. NO NO           NO   NO   NO   D. Mays     NO  
53-008 61.8 10/29/1997 53-621 YES NO NO NO On mesa top adjacent to TA-53 lagoons.  Boneyard spread along south and east sides of lagoons.  Located between Sandia and Los Alamos canyons. Very little ground cover.  Canopy cover consists primarily of junipers.   YES NO         Rill erosion is widespread across the site, primarily adjacent to the roadway.  Two small gullies are present at the southeast corner of the lagoons. YES Storm water flowing across and along side the roadway is causing erosion. NO   YES Sheet flow from the surrounding area. T. Lemke Repair of gullies and large rills.  Culvert where drainage crosses roadway.  Straw bales or other dissipaters at discharge points.   NO Very little vegetation in many locations and evidence of current erosion.

Debris on site consists of scrap metal stored in the boneyard.
53-012(a) 62.0 7/31/1998 53-60 YES NO NO NO On side of road amidst reeds, southwest of Cooling Tower 53-60.  Drains about 100 feet west on road then flows north to Los Alamos Canyon in channel cut through tuff with backhoe. At outfall it is a wetland thick with reeds.  The channel cut through the tuff is relatively bare. Flat to canyon rim then steep fall into canyon. YES YES Channel 18 inches wide up to six feet deep, cut through tuff with backhoe.     Channel leads to canyon rim. Outlets to canyon onto bare tuff surrounded by vegetation. YES Storm water runoff from road running east-west from Building 53-1 to cooling tower 53-60. YES NPDES outfall EPA 03A047. NO   D. Mays     NO  
53-012(b) 55.0 7/31/1998 53-62 YES NO NO NO Outfall from cooling tower 53-62 located directly to north. Outfalls onto bare tuff surrounded by thick vegetation. Descends slope into Los Alamos Canyon. YES YES At time of evaluation flow estimated 50 gal/min.  Runoff trickles over exposed tuff into Los Alamos Canyon.     Outfalls at canyon rim. Outfall appears stable, like PRS 53-012(a). NO   YES NPDES outfall EPA 03A048. NO   D. Mays     NO  
53-012(c) 62.0 7/31/1998 53-64 YES NO NO NO Outfall from cooling tower 53-64, located at Los Alamos Canyon rim at confluence with DP canyon. Drains onto exposed tuff. Drops off sharply into canyon. YES YES At time of evaluation flow estimated 50-75 gal/min.  Trickles over bare rocks to canyon floor.     Outfall at canyon rim. Like its brethren outfalls PRS 53-012(a) and 53-012(b), there does not appear to be soil transport, just bare rocks. NO   YES NPDES outfall EPA 03A049. YES Runoff from dirt access roads north of cooling tower 53-012(c) have formed rills leading to the outfall.  However, no visible erosion downstream of the outfall. D. Mays     NO There appears to be some unused effluent sampling equipment at this outfall, consisting of a flexible tube and a modified 55-gallon drum.  Does not appear to be a concern at this time.  But, if it is redundant, it should be removed.
53-012(d) 49.3 7/31/1998 53-28 YES YES NO NO Inactive outfall from mothballed cooling tower associated with Building 53-28.  In the photo it is the small diameter black rubber line.  The white PVC line is the Building 53-28 roof drain. Paved with asphalt. Area drains to drop inlet (see photo). YES YES Drop inlet located southwest of Building 53-28, north of Building 53-7.     Storm sewer outfalls to Sandia Canyon. Site 100% paved. YES Roof drain from Building 53-28 flows onto PRS via PVC line.  Area also collects parking lot runoff. NO Inactive NPDES outfall EPAA 03A125. NO   D. Mays     NO Debris is metal components, soil fill, broken concrete, etc.
53-012(e) 15.8 10/29/1997 53-002 YES NO NO NO Outfall from floor drain inside the maintenance/machine shop TA-53-002.  Outfall is plugged.  Located on mesa top adjacent to Sandia Canyon. Outfall located directly beneath a tree.  Ground covered with pine needles, leaves, and some grasses.   NO NO           NO   NO Outfall is deleted NPDES outfall EPA03A114. YES Sheet flow from surrounding slopes. T. Lemke     NO Outfall is no longer active.  No evidence of discharge.  Little to no exposed soil at the site.
53-012(f) 31.6 12/12/1997 53-676 YES NO NO NO Outfalls located on the north side of Sandia Canyon.  Both outfalls discharge blowdown from cooling towers around Building 53-676 and operate under the same NPDES outfall permit. Some ground cover (grasses).  Within the PRS boundary, the area consists primarily of rock.   YES YES Outfalls discharge into a channel that has been cut into the tuff (cut marks are visible) before discharging into Sandia Canyon.         NO   YES Discharges are from cooling tower blowdown.  Both outfalls operate under NPDES outfall permit EPA 03A 113. NO   T. Lemke     NO The outfall discharge flows over a solid rock base, and over rocks into the canyon bottom.  There is no visible evidence of erosion.
53-012(g) 31.6 12/12/1997 53-676 YES NO NO NO Outfalls located on the north side of Sandia Canyon.  Both outfalls discharge blowdown from cooling towers around Building 53-676 and operate under the same NPDES outfall permit. Some ground cover (grasses).  Within the PRS boundary, the area consists primarily of rock.   YES YES Outfalls discharge into a channel that has been cut into the tuff (cut marks are visible) before discharging into Sandia Canyon.         NO   YES Discharges are from cooling tower blowdown.  Both outfalls operate under NPDES outfall permit EPA 03A 113. NO   T. Lemke     NO The outfall discharge flows over a solid rock base, and over rocks into the canyon bottom.  There is no visible evidence of erosion.
53-012(h) 3.6 7/31/1998 53-19 YES NO NO NO According to Constituant Assessment (Part B Form) this is a "closed loop cooling system".  Located south of Building 53-19, northwest of Building 31. Some sparse patches but mostly covered with grass, asphalt or concrete. Fairly level. NO NO There is a drop inlet about 25 feet southwest of the NPDES outfall sign.         NO No apparent roof drains or parking lot/walkway run-on to area. NO Abandoned NPDES outfall EPA 04A133.  It appears outfall piping has been removed, though faded sign is still visible. NO   D. Mays     NO Debris misc paper items.  This assessment conducted from outside fence due to restricted access to site.
53-014 80.5 6/18/1999 53-18 NO YES NO NO Former lead-shot site located within drainage off of access road. Mixed vegetation of grasses, medium size trees and exposed tuff. Steep drainage goes to hanging valley cliff face above Sandia Canyon. YES YES Storm drains and parking lot runoff onto PRS.     Runoff from drainage goes directly into canyon. Gully erosion created from discharges from storm water culvert and NPDES outfalls. YES Run-on from parking lots and storm drains has created severe gully erosion above site. YES Active NPDES outfall (03A113) from cooling tower. NO None Veenis, Steve Flow dissipation and additional run-on diversion is needed.  Hillslope above site should be stabilized with either geotextile or cellular confinement system. Asphalt curb along roadway was installed to divert run-on off of slope above PRS. NO