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Lapwai School Dist. Bus Barn

EXECITIVE SUMMARY

The Lapwai School District 341 Maintenance Shop/Bus Barn, located in Lapwai, Idaho, had 2 dry wells that were intermittently utilized by school district personnel to dispose of pesticide rinseates. Other potential sources of ground water contamination were identified during two EPA Underground Injection Control (UIC) inspections that was conducted September 9, 2002 and June 12, 2012.  The Maintenance Forman thought the floor drains were connected to the municipal sewage treatment plant, but he was not able to provide documentation that this had occurred. It was recommended that these injection wells be further investigated and that the dry wells outside of the shop be permanently closed. The dry well’s are located less than 50 feet from municipal well BIA No. 1 and No. 2 that provides drinking water to the Lapwai Elementary School, Head Start Preschool, Nez Perce Tribal Offices, and Tribal homes totaling 300 hookups. Assessment work is on going.

SITE HISTORY

  • February 25 2002 Improper disposal of pesticide rinsate was observed coming from the bus barn at the Lapwai School District and entering a storm drain empting to Lapwai Creek.
  • February 27, 2002 Tribal Pesticide Inspector conducted interviews and a site inspection and concluded that disposal and cleaning of equipment was inconsistent with the product label directions and precautions.
  • June 12, 2012 The U.S. Environmental Protection Agency (EPA) inspected Lapwai School District facilities to determine compliance with the Safe Drinking Water Act, Class V Underground Injection Control (UIC) program.
  • August 30, 2012 Underground Injection Control (UIC) program at the U.S. Environmental Protection Agency (EPA), Region 10, notified Lapwai School District that motor vehicle waste disposal wells at the school district’s Bus Transportation and Maintenance facility in Lapwai, Idaho, must be closed in accordance with the requirements of 40 C.F.R. §§ 144.82, 144.89, and 146.1O(c).
  • September 10, 2002 Environmental Protection Agency (EPA) conducted an inspection of underground injection control (UIC) wells at the Lapwai School District. Inspection findings included a drywell (aka Bus Barn UIC) located within 50 feet of a public water supply well that has been regularly used for disposal of pesticide rinsate and motor vehicle wash water, floor drains in garage bays of a maintenance shop with unknown final discharge points, and 2 drywells in a nearby grassy area that were installed for unknown purposes.
  • September 24, 2012, the EPA received Lapwai School District’s plan to permanently close one well and assess all of the motor vehicle waste disposal wells to determine if contamination has resulted from the injection activities
  • October 11, 2012 Conditional Approval of Closure Plan for Motor Vehicle Waste Disposal Wells at the Lapwai School District Bus Transportation and Maintenance Facility, Lapwai, Idaho
  • October 23, 2012 Nez Perce Tribe Water Resources Division on behalf of the Lapwai School District Transportation Department sampled the motor vehicle and bus barn underground injection control (UIC) wells.
  • December 7, 2012 Nez Perce Tribe Water Resources Division on behalf of the Lapwai School District Transportation Department presented the sample results from Anatek Labs.
    • The soil sampled from well behind the Bus Garage, (Bus Barn UIC) primarily used to dispose of bus wash water did not exceed Idaho DEQ Initial Default Target Level (IDTL) concentrations. However, the close proximity to the BIA drinking water well (30 ft) and past disposal practices suggest that the district should develop an alternative to shallow groundwater injection of bus wash water.
    • The UIC well located in front of the building named the Motor Vehicle UIC contains grossly contaminated sludge. Ten volatile organic chemicals (VOC), three semi-volatile organic chemicals (SVOC), and three metals are present in concentrations that exceed Idaho DEQ’s Initial Default Target Levels (IDTL). In particular, the chemicals contain significant concentrations of non-biodegradable chlorinated solvents including tetrachloroethene (22.5 mg/Kg), trichloroethene (168 mg/Kg), and lead (1,840 mg/Kg). The sludge and surrounding soil around the Motor Vehicle UIC should be carefully excavated and likely disposed as hazardous waste at an appropriate licensed facility. Additionally, there is the potential that these chemicals may have contaminated the shallow groundwater. Because of the relatively close proximity to the BIA drinking water wells it is recommended that at least three shallow groundwater monitoring wells be installed around the injection well site.
  • On January 16, 2013 EPA Region 10 issued a CERCLA Unilateral Administrative Order (UAO) to the Lapwai School District, requiring removal of the dry well contents and the dry well itself, and cleanup of associated contaminated soils. The UAO required characterization and proper disposal of removed and excavated materials, and confirmation sampling and analytical results of remaining soils in the side walls and bottom of the excavation pit.
  • February 4 & 5, 2013 Drywell removal and over-excavation was performed by Roach Construction and STRATA. Upon termination, the excavation extended approximately 12 feet by 12 feet horizontally and 14.5 feet vertically. Seven drums of sludge and approximately 30 cubic yards of presumed contaminated soil had been removed and stored on site. VOC samples (after compositing) were collected, contained, and preserved referencing Environmental Protection Agency (EPA) Method 5035. Soil samples were placed in laboratory supplied containers and shipped on ice to Anatek Laboratories in Moscow, Idaho for analysis. Soil was analyzed for VOCs by EPA Method 8260B, SVOCs by EPA Method 8270D and metals by EPA Method 6020 under standard chain-of-custody procedures. Normal laboratory turnaround was requested as visual, olfactory and PID evidence during excavation suggested contamination was left in place and additional cleanup alternatives would be warranted.
  • February 25, 2013 Analytical results indicate that high levels of TCE, PCE and some other VOCs remain in soils beyond the 14.5 foot extent of excavation of the earlier removal. Additional CERCLA 104(b) removal site investigation activity will be necessary to fully characterize the extent of and threats posed by the remaining contaminant plume.
  • March 7, 2013 the OSC, the Lapwai School District and their contractor held a teleconference to discuss data and a proposed investigative approach to evaluate remaining contamination at the site. EPA had proposed an investigative approach that would require installation of soil borings and monitoring wells. The School District had scoped the cost of doing such work and had determined that they did not have the financial resources to carry on the necessary work, and requested that EPA take over the lead for additional necessary work at the site. The School District indicated that they would continue with managing appropriate disposal of excavated and stockpiled waste that remains at the site, and then be done except for coordination with EPA.
  • April 9, 2013 Lapwai School District submitted a letter of intent for UIC closure
  • April 30, 2013 Lapwai School District submitted pictures of bus barn UIC drywell closure
  • May 17, 2013 The Nez Perce Tribal Historic Preservation Office was consulted to identify possible impacts to historic properties from conducting a passive soil vapor survey
  • June 2013, EPA mobilized to the site to perform a passive soil gas survey to inform an anticipated subsequent shallow subsurface soil and groundwater investigation. The soil gas survey included the installation of 49 passive shallow soil gas samplers deployed in a grid around the Site. The soil gas survey results indicated the presence of PCE and other VOCs in subsurface soil at the Site.
  • February 2014 A enhanced utility locate was conducted in support of the UIC closure of Lapwai School Dist. Dry Well. A possible remaining UST in the parking lot south – southeast of BIA Well#1.
  • February 2014, EPA mobilized to the Site to advance five soil borings and monitoring wells. A vapor intrusion investigation was also performed to assess the potential for VOCs to migrate from the subsurface soil into the nearest residence located 100 feet to the south of the property.
  • March 2014, groundwater samples were collected from the five monitoring wells and two municipal wells.
  • July 2014 The Nez Perce Tribe collected a second round of groundwater (5) and drinking water (2) samples at the Site. Low concentrations of PCE and TCE in the two impacted monitoring wells had dropped from the February sampling and there were again no detections in the two BIA drinking water wells. The data supported EPA’s conclusion that residual contamination remaining in shallow groundwater and unconsolidated soils next to the former dry well do not appear to represent an immediate threat to the nearby drinking water wells.
  • January 2015 Letter to Lapwai School DIst requesting removal of UST.