Tribal Unit 45 (TU-45)

EXECUTIVE SUMMARY: Over a period of seven years the Nez Perce Tribe Tribal Response Program (TRP) investigated the 39-acre former sawmill site, Riverside/Richardson’s Sawmill (TU-45), located on the Nez Perce Reservation 1.5 miles east of Orofino, ID. The Tribe’s Economic Development Office was reluctant to redevelop the property due to uncertainties related to possible environmental contaminants. The TRP investigated eight possible contaminants, with a main focus on the identification of a clean source of drinking water unaffected by existing contaminants. Through a detailed soil sampling program and the drilling and sampling of 16 groundwater monitoring wells, the TRP has developed a comprehensive understanding of the distribution of contaminants on both the surface and subsurface and have documented the direction of groundwater flow across the site. Of the eight contaminants investigated, only perchlorate was found in levels exceeding the maximum contaminant level goals in groundwater as defined by the EPA. Two proposed drinking wells (MW-12 and MW-13) have been drilled on the north side of the property. They have been testing through pumping, sampling, and chemical analysis. Through interpretation of the hydrogeology at the site, the TRP believes these two wells are capable of providing clean drinking water to support site development. Creosote contamination was found in one half acre area on the southwest side of the property and scattered pentachlorophenol exceedances were found in soil, but not groundwater.

The water from the two proposed drinking water wells (MW-12 and MW-13) has been interpreted to come primarily from the riverbed of the adjacent Clearwater River. These wells are located upgradient on the aquifer and across the site from the likely source of the perchlorate contamination, which is carried by the groundwater flow paths to the northwest where it discharges into the Clearwater River. Long term pumping tests and sampling documented that these water wells produced clean water. Water level monitoring of the adjacent wells during the pumping tests documented that there was no measurable deflection of the water table, which indicates that the wells were unlikely to draw contamination towards the currently clean wells.

The TRP’s recommendations for Institutional Controls at the site were accepted by the Nez Perce Tribal Executive Committee. These three institutional controls were designed to manage environmental exposure to existing contamination and eventually eliminate ongoing and future contamination. With these institutional controls in place, this beautiful site is ready for redevelopment.


  • 2018 Report for Phase II ESA was submitted to the EPA
    • NPTEC placed 3 institutional controls on the site
  • 2016 Continuing Phase II Assessment that was completed in 2017, work included:
    • Quality Assurance Project Plan and Sampling Analysis Plan approval
    • Install 9 additional monitoring wells and collection of soil and water samples
    • Investigation of abandoned underground storage tank (UST)
  • 2015 Site used as a fire camp during the 2015 fire season and site cleanup was performed.
  • 2014 Phase I ESA updated to include current findings
  • 2014 Awarded EPA Assessment Grant to conduct remaining Phase II Assessment
  • 2012 to 2014 Phase II Assessment work performed that included
    • Excavation of creosote pad and soil sampling
    • Drill holes in transformer building cement floor and sampled soils for PCB
    • Passive soil gas sampling
    • Installed 4 monitoring wells and collected drill core and water samples
  • 2011-December received final report from Ecology and Environment, Inc.
  • 2010-Concerns assessed by EPA’s contractor; Ecology and Environment, Inc.; and Tribal Cultural Resources office conducts archeological assessment
  • 2010 Work funded by EPA through a Targeted Brownfields Assessment
  • 2009-Recognized environmental conditions identified by a Phase I ESA

SITE HISTORY The Nez Perce Tribe (Tribe), Water Resources Division requested a property specific funding determination to continue with a Phase II Environmental Site Assessment on TU-45. Tentative redevelopment plans include a recreational venue, tourist facilities with a proposed boat ramp, tackle shop, and rental cabins. Tribal Unit (TU)-45 is a 38.9 acre property located 1.3 miles southeast of Orofino, Idaho, along the south bank of the Clearwater River. This property is managed in Trust by the Bureau of Indian Affairs (BIA) for the Nez Perce Tribe (Tribe). Current site activities include Teweepuu Community Center, Tribal Fisheries Office, and recreation focusing on fishing, swimming, walking, and seasonal fireworks detonation and sales. The significant historic uses of the site include the Richardson/Riverside Sawmill (1942-1980), Sverdsten Logging, sorting yard, (1983-1984), Seubert Excavators, asphalt batch plant, (1987-1991), WASCO, depositing demolition debris (1997), and various fireworks stands (1983-2014). A Phase I Environmental Site Assessment (ESA) was performed on TU-45 in conformance with the scope of work and ASTM Practice E 1527-05 in March 10, 2010. A Targeted Brownfield Assessment was funded and managed by EPA was completed in December 2011 and concluded that additional site characterization was needed. A Phase II ESA, managed and funded by Tribal Response Program (TRP), began in 2013 and includes trenching, soil sampling, geophysics, drilling of four monitor wells, and groundwater sampling. This revised Phase I ESA incorporates findings from the TBA, Phase II ESA findings to date, and presents the following professional opinions regarding recognized environmental conditions (RECs) at TU-45:

  1. Creosote contaminated soil and possible creosote groundwater contamination
  2. Underground Storage Tank (UST);
  3. Uncharacterized “demolition debris”
  4. Perchlorate contamination of groundwater from fireworks detonation
  5. Soil and possible groundwater contamination by pentachlorophenol of unknown origin.
Tribal Unit 45 (TU45) Location and REC Map

Tribal Unit 45 (TU45) Location and REC Map