HYDROLOGIC (SURFACE WATER) CONSIDERATIONS FOR REMEDIAL

INVESTIGATIONS AND FEASIBILITY STUDIES OF CONTAMINATED SITES

Objectives

Analyses of soil and ground water contamination and development of remediation strategies require significant key input from the surface water hydrologist. In many cases the input has to be defended through a legal deposition and/or expert testimony. This task committee will identify required hydrologic analyses, state-of-the-art methodologies to perform such analyses, and procedures for technical and legal defense of such analyses and relevance of the results of such analyses for specific sites.

A preliminary outline of the hydrologic input proposed to be addressed by the task committee is given below:

C Identification of significant storms of the past capable to transport contaminated sediments to the nearest stream and/or surface water impoundment and event-based rainfall-runoff modeling to quantify transport of contaminated sediments during such storms.

C Continuous rainfall-runoff simulation to estimate infiltration at site and recharge to ground water along potential pathway of contaminant transport with ground water.

C Assessment of sorption from contaminated sediments with estimated infiltration resulting in reduction in source contamination and release of contamination to ground water.

C Continuous stream flow analysis to estimate desorption of contaminants from deposited sediments.

C Data collection and calibration.

C Stream flow analysis to forecast future flows, permitted loading of contaminants of concern, and assimilative capacity with and without remediation.

C Limitations and/or confidence levels and applicability of hydrologic estimates.

The product of the task committee will be an ASCE report documenting procedures for hydrologic analyses and modeling related to remedial investigations and feasibility studies (RI/FS) of contaminated sites, two to three technical papers for presentation in conferences, one session in an ASCE conference ( in Seattle in 1999), and possibly a journal paper.

Schedule of Activities

First Year ending September 30, 1999 Compilations of technical papers for presentation at the Seattle Conference.

Second Year ending September 30, 2000 Report Preparation

Third Year ending September 30, 20001 Report Finalization

Accomplishments

Last year (ending September 30, 1999), the committee compiled eight technical papers. They were presented in three different sessions in Seattle.

A draft Table of Contents for the report of this Task Committee is enclosed. The drafting of the report began October 1, 1999.

So far the following preliminary drafts have been completed:

1.01 Introduction

1.1 Definition and Requirements for Remedial Investigation and Feasibility Studies

1.2 Objectives

1.3 Scope of Study

1.4 Regulatory Perspective

1.02 Data Requirements

1.03 Remedial Technologies and Limitations

1.04 Relevant Hydrologic Processes and Simulation

5.0 Water Quality Issues Related to Wetlands, Federal Permits, and other legal Issues.

6.0 Methods of Analyses and Their Limitations

7.0 Illustrative Applications

8.0 References

Drafting, editing, and internal review will continue through the coming year until September 20001.

Draft is expected to be completed and reviewed by end of next year.