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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 73-001(a) 85.5 10/15/1997 YES NO YES NO Site of former town and laboratory landfill. Located between Pueblo Canyon and airport runway. Landfill debris also found off edge of cliff in drainages discharging into Pueblo Canyon. Ground cover on mesa is well vegetated, debris exposed on mesa edge. Cliff below landfill is shear, with visible debris below site. YES YES Manmade channel extending from storm drain at edge of runway to edge of Pueblo Canyon. Sheet flow and minor/severe channelization evident across entire landfill site. Termination of runoff is Pueblo Canyon. Rill erosion between perimeter fence and canyon edge. Severe gully erosion occurring in the central east facing lobe of landfill. YES Storm drains conveying run-off from airport runway. NO NO T. Lemke Remove debris from watercourse, provide run-on controls and sediment/erosion controls. Run-on control above exposed north facing debris pile (culvert) has been installed as a diversion practice. Gabion was placed at end of culvert for dissipation NO Evidence of erosion exists.
Metal, paper and asphalt located in and around drainage channel near perimeter fence. Additional debris scattered around site (tires, sheet metal, concrete, rebar, misc. debris).73-002 56.0 10/15/1997 73-2 YES YES NO NO South side of Pueblo Canyon behind old incinerator building TA-73-2. PRS extends from edge of mesa top to small bench within canyon. Incinerator surface disposal. Sparse vegetation. Primarily rock and debris from former incinerator activity. Steep slope along side of canyon. YES NO Bench within Pueblo Canyon Rill from edge of mesa top extending half way to bench. YES Run-off from concrete pad behind Building TA-73-2. NO YES Sheet flow down surrounding slope. T. Lemke Straw bales in place along edge of mesa top. BMPs installed 4/30/96 NO Steep slope with bare soil at edge of mesa top. Evidence of erosion exists.
Site is covered with ash and rusted cans deposited into canyon from incinerator activity.73-003 10.6 10/15/1997 YES NO NO NO In parking lot adjacent to airport runway, south side of Pueblo Canyon. Former garbage truck, dumpster, and can clean-up area. Area covered with asphalt. NO NO YES Run-off from adjacent asphalt areas. NO NO T. Lemke NO 73-004(a) 3.6 10/15/1997 73-2 YES NO NO NO South side of Pueblo canyon behind incinerator building TA-73-2. Site of old septic tank. Area covered with jute matting and ground cover. NO NO NO NO NO T. Lemke Jute matting is effective at site. BMPs installed 4/30/96. NO 73-004(b) 10.6 10/15/1997 73-2 YES NO NO NO In parking lot between airport runway and Pueblo Canyon. Site of former septic tank. Area covered with asphalt. NO NO YES Run-off from adjacent asphalt. NO NO T. Lemke Straw bale berms were installed below site to keep sediment in place. Excavated areas were reseeded and jute mat was installed BMPs installed 4/30/96. NO 73-004(c) 10.6 10/15/1997 YES NO NO NO Site of former septic tank, under concrete pad (airplane parking area) adjacent to airport runway, south side of Pueblo Canyon. Area covered with concrete. NO NO YES Run-on from adjacent concrete areas. NO NO T. Lemke NO 73-004(d) 46.7 10/15/1997 YES NO NO NO Septic system that served the landfill office located east of the present airport terminal building and within the footprint of PRS 73-001(a). A 4 in. diameter vitrified-clay pipe (VCP) connected the building's toilet to the septic tank located about 20 ft northeast of the building. The building and septic tank were removed as part of the decommissioning operation in the early 1970s. Ground cover on mesa is well vegetated, debris exposed on mesa edge. Cliff below landfill is shear, with visible debris below site. YES YES Manmade channel extending from storm drain at edge of runway to edge of Pueblo Canyon. Runoff from PRS is sheetflow Sheet flow and minor channelization evident across entire landfill site. Termination of runoff is Pueblo Canyon. Sheet erosion inferred due to runoff evidence from area. NO Run-on diversion trench intercepts runon to site. NO No operational impacts NO No natural drainage due to trench. Veenis, Steve Remove debris from watercourse, provide run-on controls and sediment/erosion controls. Run-on control above exposed north facing debris pile (culvert) has been installed as a diversion practice. Gabion was placed at end of culvert for dissipation. NO Evidence of erosion exists.
Metal, paper and asphalt located in and around drainage channel near perimeter fence. Additional debris scattered around site (tires, sheet metal, concrete, rebar, misc. debris).73-005 27.6 7/2/1998 YES NO NO NO Sites are in the former contractor row south of State Road 502 and south of the airport. Sites drain into DP Canyon. Area is covered with native grasses, oak and pine. Area is on the mesa top. YES NO Two natural channels drain area. Larger channel also drains area along State Road 502 and the airport. Run-off goes over mesa edge into DP Canyon. Two natural drainage channels. NO Run-on from State Road 502 is channelized through the site. NO One very old hydrant in area. NO Sheet flow across into small channels within the site. T. Lemke None at this time. NO Minimal soil erosion. 73-006 56.0 10/15/1997 73-2 YES YES NO NO South side of Pueblo Canyon behind old incinerator building TA-73-2. PRS extends from edge of mesa top to small bench within canyon. Incinerator surface disposal. Sparse vegetation. Primarily rock and debris from former incinerator activity. Steep slope along side of canyon. YES NO Bench within Pueblo Canyon Rill from edge of mesa top extending half way to bench. YES Run-off from concrete pad behind Building TA-73-2. NO YES Sheet flow down surrounding slope. T. Lemke Straw bales in place along edge of mesa top. BMPs installed 8/31/96. NO Steep slope with bare soil at edge of mesa top. Evidence of erosion exists.
Site is covered with ash and rusted cans deposited into canyon from incinerator activity.73-007 56.0 7/2/1998 YES NO NO NO Septic tank and drainline located near "contractor row" south of State Road 502 and south of the airport. Area is partially barren but has some vegetative cover of native grasses, oak and pine trees. Former septic tank was on the mesa top, drainline discharged near mesa edge. YES YES Ther former drainline had a trench associated with it which directed flow over mesa's edge and into DP Canyon. Other runoff from area is sheetflow in nature. Run-off goes over mesa edge into DP Canyon. Rill erosion was observed near area where drainline was removed. NO No structural impact observed. NO No current operational impact. YES Upslope sheetflow from State Road 502. Veenis, Steve None at this time. NO Site re-assessed due to information provided within the RFI Report. Original assessment performed on 7/2/98 which generated a score of 27.6. C-73-005(a) 47.2 3/27/2000 YES NO NO NO Septic pit located near the area known as "contractor row" south of State Road 502 and south of the airport. Area is partially barren but has some vegetative cover of native grasses, oak and pine trees. Septic pit area is on the mesa top, outlet pipe discharged near mesa edge. YES YES The former outlet line had a trench associated with it the directed flow towards mesa edge. Other runoff from area is sheetflow. Run-off goes over mesa edge into DP Canyon. No erosion observed, but sheetflow erosion can be inferred. NO No structural impact observed. NO No current operational impact. YES Upslope sheetflow from State Road 502. Veenis, Steve None at this time. NO Site re-assessed due to information provided within the RFI Report. Orignal assessment performed on 7/2/98 which generated a score of 27.6. C-73-005(b) 47.2 3/27/2000 YES NO NO NO Septic pit located near the area known as "contractor row" south of State Road 502 and south of the airport. Area is partially barren but has some vegetative cover of native grasses, oak and pine trees. Septic pit area is on the mesa top, outlet pipe discharged near mesa edge. YES YES The former outlet line had a trench associated with it the directed flow towards mesa edge. Other runoff from area is sheetflow. Run-off goes over mesa edge into DP Canyon. No erosion observed, but sheetflow erosion can be inferred. NO No structural impact observed. NO No current operational impact. YES Upslope sheetflow from State Road 502. Veenis, Steve None at this time. NO Site re-assessed due to information provided within the RFI Report. Orignal assessment performed on 7/2/98 which generated a score of 27.6. C-73-005(c) 27.6 2/14/2000 YES NO NO NO Sites are in the former contractor row south of State Road 502 and south of the airport. Sites drain into DP Canyon. Area is covered with native grasses, oak and pine. Area is on the mesa top. YES NO Two natural channels drain area. Larger channel also drains area along State Road 502 and the airport. Run-off goes over mesa edge into DP Canyon. Two natural drainage channels. NO Run-on from State Road 502 is channelized through the site. NO One very old hydrant in area. NO Sheet flow across into small channels within the site. Veenis, Steve None at this time. NO Minimal soil erosion.