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Field Demonstration Work Plan for ESTCP Project 20020 - PIMS
Section 1 - Introduction
Lead-contaminated soils are prevalent in the United States particularly at Department of Defense (DoD) sites that have small arms firing ranges or testing facilities. Lead is the principal component of projectiles (bullets) used at small-arms firing ranges. Consequently, assessment and cleanups at these sites focus predominantly on the presence of lead in soils and other environmental media. Lead is chemically stable and not biodegradable. High levels of lead and lead compounds are known to induce disease and toxicity in high risk receptors (e.g., children, pregnant women) (U.S. Environmental Protection Agency [USEPA], 1991a, 1994a, and 1994b). The Center for Disease Control (CDC) has repeatedly lowered the human blood level of concern from 40 micrograms per deciliter (mg/dL) in 1978, to 25 mg/dL in 1990, to the current blood level of concern of 10 (mg/dL).
To date, a nationally recognized �safe� lead concentration in environmental media has not been developed. Lead is ubiquitous and can occur naturally in surface and shallow soils at concentrations ranging from 5 to 50 parts per million (ppm). Therefore, USEPA has focused predominantly on reducing the potential for sensitive populations to be exposed to anthropogenic (human-made) lead sources (e.g., industrial emissions, leaded gasoline, and paint) and environmental media contaminated with lead as a result of human activities (e.g., sites of mineral extraction, smelting operations, and potentially firing ranges).
Therefore, to potentially address lead-contaminated media from anthropogenic sources, a treatment method often used is solidification/stabilization. Solidification is the encapsulation or physical adhesion of waste on a micro or macro scale into a more solid material. Stabilization is the conversion of contaminants into a less soluble, less mobile, or less toxic form. Solidification/stabilization is recognized by the USEPA as an effective remediation process for treatment of soils contaminated with lead and other metals (USEPA 1997). Solidification/ Stabilization technology is most promising where future access is relatively secure (such as continued use as a military base). Because lead will remain in the soil and may continue to pose a potential risk, long-term monitoring and record keeping are necessary to ensure stabilization remains effective.
The primary goal for solidification/stabilization at lead-contaminated sites will typically be to reduce leachable lead levels below the Toxic Characteristic Leaching Procedure (TCLP) hazardous waste criterion of 5 mg/l, or the universal treatment standard for soil of 7.5 mg/l. Several specific solidification/stabilization technologies are potentially applicable to lead contaminated sites, as listed below:
Portland Cement: Conventional cement-based process in which materials are mixed with Type I Portland� cement to encapsulate (solidify) the lead.
Pozzolantic Material: Involves blending lead contaminated soils with siliceous and aluminosilicate materials. The primary mechanism is the physical entrapment (solidification) of contaminant in the pozzolans, such as fly ash, pumice, lime kiln dusts, and blast furnace slag.
Emulsification Fixation and Reuse: Lead contaminated soil can be blended with water based asphalt emulsion (or other organic binding material) and varying amounts of aggregate to produce a range of cold-mix asphaltic products. These products can be used as structural backfill, parking lot pavement, and road construction material, as well as chemical stabilization of lead in soils. This method is most appropriate for sandy soils, not fine-grained soils.
Phosphate-Based Chemical Fixation: Phosphate-based stabilization method that involves formation of relatively insoluble lead phosphates (e.g., pyromorphites) upon application of sufficient quantities of apatite, calcium phosphate, phosphoric acid, or other phosphate-based particulate material directly into lead-contaminated soil. The proposed field demonstration project uses this type of chemical stabilization method with an apatite-type phosphate material, referred to as Apatite II).
Phosphate-Induced Metal Stabilization (PIMS) is a technology that stabilizes metals using a natural additive, Apatite II. Apatite II can chemically bind soluble metals into new stable, insoluble phases in which the metal is no longer bioavailable. PIMS technology may be ideal for remediating metal-contaminated soil, in situ or ex situ, particularly lead. The demonstration at Camp Stanley Storage Activity (CSSA) in Boerne, Texas is a soil remediation using soil mixing of Apatite II into lead-contaminated surface soils under unsaturated conditions at Solid Waste Management Unit (SWMU) B‑20 a former open burn/open detonation (OB/OD) area at CSSA. Site treatability study activities include emplacement of the Apatite II/lead-contaminated soil mixture for a field demonstration, site monitoring, and post-emplacement testing. The amount of soil to be remediated in this demonstration is approximately 500 cubic yards. The cost savings and ease of operation are the benefits of this technology relative to other technologies such as soil washing or other stabilization techniques, e.g., solidification with Portland� cement.
CSSA is the lead in this demonstration, and all activities must be coordinated by them and their subcontractor, Parsons Engineering Science, Inc (Parsons ES). These activities fall under Parsons ES site protocols, regulatory umbrella, and Quality Assurance Project Plan (QAPP) (including analytical). There have been two Remedial Investigations (RI) at the SWMU B-20 site, and some of that information is incorporated into this Work Plan.
1.2 - Objectives of the Demonstration
The objective of this demonstration is to treat lead-contaminated soils at an ordnance treatment unit so the soil poses no further health threat or environmental hazard and can be released back to the site in a manner consistent with regulatory approval and future site use plans. This demonstration serves two purposes:
Validate the efficacy of the technology in the field at a full-scale operation, and;
Transfer the technology to an end-user (e.g.; CSSA).
The contaminant is particulate lead in soil from ordnance and firing range activities. The soil has been excavated, sifted, and placed into five approximately 500 cubic-yard piles, of which one pile will be used in this demonstration. This demonstration will validate the efficacy of the PIMS technology for soil remediation of lead-contaminated soils and, potentially, for other firing and ordnance range applications. The potential advantage of this technology, which will be proven with the field demonstration, is the ease of application resulting in significant cost-benefits versus off-site disposal or other treatment technologies such as solidification or soil washing.
The USEPA Region VI and the Texas Natural Resource Conservation Commission (TNRCC) are the two agencies having regulatory authority, and both are requiring disposition of this contaminated soil. Both agencies have expressed support for this demonstration and have hopes that its success will lead to accelerated clean-up of similar sites in Texas and elsewhere.
The remedial investigations and closure of SWMU B‑20, a former OB/OD area, is being conducted by Parsons ES and CSSA in compliance with a Compliance Order dated June 30, 1993. Additionally, an Administrative Order on Consent was entered into between CSSA and the USEPA, Region VI, proceeding under � 3008(h) Resource Conservation and Recovery Act (RCRA), dated May 5, 1999. The compliance order required the SWMU B‑20 closure plan comply with federal and state regulations (40 Code of Federal Regulations [CFR] 265 Subpart G, and Title 30 Texas Administrative Code [TAC] Chapter 335 Subchapter S, respectively) for closure of hazardous waste management units.
Success of this demonstration could be determined by the current applicable closure criteria, i.e., Texas Risk Reduction Standard 1: remediation to background levels, no deed restriction required; or by Risk Reduction Standard 2: remediation to risk-based numbers, deed restriction required. Alternatively, success can be based on newly promulgated Texas Risk Reduction Program (TRRP) closure criteria, i.e., Texas Tier 1: remediation to risk-based numbers, no deed restriction required. Discussions with base personnel and regulators will determine these levels and acceptable values, background levels, standards for closure, etc. Field monitoring of the site after treatment is expected to show no leachable lead leaving the treated soil above regulatory levels and movement of soluble lead from the particulate phase to precipitation as insoluble lead phosphates associated with the Apatite II stabilizing agent. A layer of uncontaminated surface soil with a vegetative or rock cover will further isolate the treated soil from contact with the public or the environment. It is anticipated that this technology will not meet the Risk Reduction Standard 1 criteria due to the non-removal of the contaminant. It is however, expected to meet the risk based closure standards (e.g., Risk Reduction Standard 2 and TRRP).
1.4 - Stakeholder/End-User Issues
The outcome of this demonstration will impact whether CSSA and the DoD will use this technology in the future. A successful demonstration could likely lead to widespread use of the technology as it is anticipated that this technology will be a cost-effective alternative to other technologies currently available.