Fort Polk Abandoned Digester

Project: Fort Polk Abandoned Digester (BLDG 8716) Project Series

  1. RCRA Facility Investigation & Abandoned Digester Sludge/Liquid Sampling
  2. RCRA Corrective Measures Study
  3. RCRA Corrective Measures Implementation Design
  4. RCRA Corrective Measures Implementation (Digester Sludge/Liquid Removal/Disposal & Digester Demolition)

Location: Fort Polk North Waste Water Treatment Plant

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Project Summary

Fort Polk North BLDG 8716 was a waste water multi-digester used as a component of the North Fort Waste Water Treatment Plant (NFWWTP) for approximately 30 years from 1942 to the 1970s. The digester consisted of a top (aerobic digestion) and bottom (anaerobic digestion) chambers, with approximately 50% of the entire digester, or 75% of the bottom chamber, below grade.

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After decommission in the 1970s, BLDG 8716 was left in place along with top and bottom chamber liquid and sludge contents. Visual observations of the exposed digester components (sidewalls, roof, sampling port manway access points, etc.) indicated compromised structural integrity and release of contents (weeping sidewalls and submerged manway). Hazardous/Non-hazardous characterization data was not available for BLDG 8716 liquid or sludge contents. JESCO conducted a RCRA Facility Investigation (RFI)/RECAP Site Investigation in 2011 which including installation of 13 borings and 5 permanent monitoring wells and sampling for full suites of Metals, Volatile Organic Compounds (VOCs), Semi-Volatile Organic Compounds (SVOCs), Gasoline Range Organics (GRO), and Diesel Range Organics (DRO).

The 2011 RFI activities also included characterization of top and bottom chamber liquid and sludge contents of BLDG 8716. Rooftop manway ports enabled access to top chamber contents. However, development of a novel sampling approach was required to sample bottom chamber contents because most of the bottom chamber was below grade and the bottom chamber’s below grade manway with sample collection ports was submerged. JESCO excavated a portion of the bottom chamber sidewall in order to install custom hot-tap sampling ports from which digester liquid was sampled at discrete depths and characterized without spilling any liquid or sludge.

Once drained in a later project phase, the bottom chamber was opened with heavy equipment to facilitate bottom sludge sampling. JESCO used collected soil and water data to delineate horizontal and vertical extents of soil and groundwater contamination, develop a Resource Conservation and Recovery Act (RCRA) Facility Investigation Report (RFI) / Louisiana Department of Environmental Quality Risk Evaluation and Corrective Action Program (LDEQ RECAP) Report, and develop RCRA Corrective Measures Study and RCRA Corrective Measures Design reports.

JESCO performed the following activities for the RCRA Corrective Measures Implementation Project in 2014:

Processing of liquid digester contents and a portion of sludge contents through the NFWWTP facilities required close coordination between JESCO and NFWWTP to schedule processing periods and volumes in concert with NFWWTP operations and capacity. Demolition of the active NFWWTP facilities occurred simultaneously with BLDG 8716 demolition and also required extremely close coordination with the NFWWTP operations contractor and demolition contractors.

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