SAP Addendum Specific to Field Sampling Plan for Subsurface Soil Boring Activities at AOC-65 and AOC-67 under AETC DO 5084

March 2001

1.0 - Introduction

This document is an addendum that modifies the Sampling and Analysis Plan (SAP) for SWMU Closures at CSSA (Environmental Encyclopedia Volume 1-4, Field Sampling and Analysis Plan tab and QAPP tab) for the subsurface soil boring activities planned at AOC 65 and AOC 67 as specified in AETC Delivery Order 5084. The purpose of this addendum is to address changes to the existing SAP specifically related to the RFI at AOC 65 and AOC 67.

2.0 - Subsurface Soil Borings Overview

Fourteen soil borings will be advanced inside and around Building 90 for investigation activities. The drilling is part of an environmental investigation at AOCs 65 and 67. These borings will be advanced using hollow stem auger and air coring methods. Parsons ES will oversee the drilling, sampling, and plugging of these borings. Five of these soil borings will be reamed and completed as permanent monitoring wells by CSSA for possible characterization of shallow groundwater in the vicinity of Building 90.

Ten soil borings will be drilled at AOC 65 to a maximum depth of 35 feet. Locations of these borings will be biased toward �hot spot� locations identified during the soil gas survey. The actual locations of soil borings at AOC 65 will be determined after completion of the soil gas survey. An additional boring will be drilled at the outfall of the Building 90 drain line to a maximum depth of 35 feet. A skid-mounted hollow stem auger rig (no air core drilling inside Building 90) will also be used to drill and sample three soil borings inside Building 90 to a maximum depth of 20 feet. One boring will be completed at the former (old) vat, and two borings will be completed in the former drain line area. These locations may be modified based on soil gas survey results from inside the building.

Three soils borings will be drilled at AOC 67 to a maximum depth of 35 feet at the low-point of the concrete pad (one boring) and in the ditch located east of Building 90 (two borings). Water is not expected to be encountered in any of these three borings, but if discovered, a grab sample of the perched water may be collected and analyzed for the same parameters as the soil samples. Up to three (3) perched water samples and associated QC samples are included under delivery order 5084.

The borings outside Building 90 in AOC 65 and AOC 67 will be augered to refusal, and then air cored to 35 feet below grade. The borings will be left open over-night to see if perched water accumulates. If perched water is found, perched water will be sampled for off-site laboratory analysis before the borehole is plugged. For boring locations selected for monitoring well construction, the perched water sample(s) will not be collected until after the well completion activities for all 5 monitoring wells are complete.

The monitoring wells will enable CSSA to collect shallow groundwater data over an extended period of time and under various weather conditions that may affect shallow groundwater in the immediate area of Building 90. Information from the monitoring wells will be used to develop shallow groundwater gradient maps and volatile organic compound (VOC) contaminant loading around the Building 90 area.

Drilling and sampling of the initial core holes includes collection and analyses of 28 soil/rock samples (2 per boring). All soil borings that are not converted to monitoring wells will be abandoned in accordance with the FSP, while monitoring wells will be constructed as described in the FSP. It is anticipated that three soil borings will be drilled each workday. Well construction will begin at the last core hole drilled during the workday. CSSA will be primarily responsible for oversight of the well construction activities. Well installation will entail reaming the initial core hole to an eight-inch diameter, installation of two-inch PVC screen and riser pipe, placement of sand pack, bentonite and grout, and construction of a flush-mounted surface completion. The surface completion will include a box cover and three-foot by three-foot concrete pad.

Other related work that may eventually be required as part of this phase of the AOC RFIs include surveying the elevations of the monitoring wells; collection of periodic water levels from the wells; purging, sampling, and the collection and analyses of groundwater samples from the wells; and completion of a report summarizing the findings of the monitoring well installation project.

2.1   Procedures for Sampling Activities

Only one modification is needed for the drilling methodology described in Section 1.1.4 of the SAP. This modification allows for the collection of a perched groundwater sample in the borehole, if present. Experience in the areas of AOC 65 and AOC 67 indicates that perched groundwater may be present in that locality. However, this may not be consistent for all the drilling locations, and will likely be related to the amount of recent precipitation. Monitoring well borings will not be sampled until after all 5 wells have been completed.

As a daily procedure, all open boreholes will be monitored for the accumulation of groundwater. Groundwater accumulation will be measured using either an electric level measuring device, a weighted surveying tape, or a Teflon� bailer. When perched water is encountered or accumulated, CSSA will be notified. CSSA may opt to have a sample collected for analysis at a local laboratory (contracted independently by CSSA).

Two soil samples will be submitted for analytical testing from each AOC 65 and AOC 67 boring in accordance with the SAP. Sampling intervals will be selected based on observations and field screening results during the drilling process. At a minimum, one sample will be collected from the top 2 feet of the borehole, one sample from the borehole terminus, and one sample from the highest PID reading observed along the retrieved soil cores. Only two samples per borehole will be submitted to the laboratory. The selection will be based on data objectives such that surface ingestion (top 2.5 feet) and groundwater protection (highest screening level) will be used to select which samples will be shipped to the laboratory for analysis. For instance, if screening indicates no elevated readings, the samples may be collected from the two samples closest to the surface. If contamination is indicated throughout the soil core, the selected sample intervals will consist of the highest PID reading and the borehole terminus, to gather data on vertical extent of contamination. Samples from the top two feet shall also be considered to provide data to address surface exposure pathways.

In addition, all core material produced during drilling activities will be placed in core boxes provided by CSSA, and taken to Building 77 for storage.

2.2   Contaminants of Concern and Analytical Methods

The constituents of concern for AOC 65 and AOC 67 include VOCs, SVOCs, metals, PCBs, and TPH. The soil samples will be analyzed for the analytes listed in Table 1. Perched groundwater samples will be tested for the same analytes following the methods in Table 1. Analytical technique will follow procedures described in Test Methods for Evaluating Solid Waste, USEPA, SW-846, and Version 3.0 of HQ AFCEE QAPP (Environmental Encyclopedia, Volume 1-4, QAPP tab). Per the updated QAPP, ambient blanks will be collected during each day of soil sampling efforts at AOC 65 and AOC 67.

Table 1 - Constituents of Concern and Methods of Analysis
for the AOC RFIs (Soil Sampling)

2.3   Sample Identification

A sample numbering system will be used to identify each sample collected during the field investigation and for all samples. The numbering system will be a tracking mechanism to allow retrieval of information about a particular location and to ensure that each sample is uniquely numbered. The field team leader will maintain a listing of sample numbers. Each sample will assume the format described below.

There will be an alphanumeric identification code unique to each sampling location. Equipment rinsate and trip blanks will also be identified using an alphanumeric identification code. The field team leader will note in the field logbook which volatile samples are associated with each trip blank during shipment to the laboratory. Each sample number will consist of a location identification code and consecutive sample number. Samples collected from soil borings will have the depth at which the sample is collected in parentheses following the sample number. The number system for duplicate samples will begin with the number 100.

The first two characters of the sample identification number will be one of the following: