January 1999

Introduction

This document is an addendum that modifies the existing SAP for the Closure of SWMUs during field activities for Delivery Order RL74. The purpose of this addendum is to identify the field activities for RL74 and verify that the activities are explained in the SAP or addenda.

This addendum to the SAP has been prepared to comply with all appropriate regulatory requirements of 30 TAC �335 for clean closure under Risk Reduction Standard Number 1. This plan describes the sampling procedure that will be implemented during closure activities to satisfy regulatory requirements.

Field Activities

Field activities to be completed under RL74 include:

1. Complete soil borings and collect soil samples at O-1 for laboratory analysis.

2. Excavate contaminated soil at O-1.

3. Collect waste characterization samples at O-1.

4. Stabilize, if necessary, and dispose of contaminated soils.

Procedures for Sampling Activities

No changes to the SAP or addenda for RL33, DO23 and RL53 are needed to implement and complete the field activities listed above. Procedures for drilling soil borings and collecting soil samples are provided in the original SAP. Procedures for excavating and stabilizing soils are provided in the RL33 Addenda.

Constituents of Concern and Analytical Methods

In accordance with 30 TAC Chapter �335 Subchapter S, for closure under Risk Reduction Standard 1, cleanup levels shall be attained using analytical procedures taken from the Test Methods for Evaluating Solid Waste, EPA, SW-846, September 1994.

The contaminants of concern for O-1 include PCE, toluene, m,p-xylene, cadmium and chromium. Samples collected at O-1 will be analyzed using the methods listed in Table 1. Laboratory results, including PQLs, will be reported. Complete laboratory quality assurance/quality control will be kept on file in the event of a request for more information from TNRCC.