Work Item
ASTM WK76688

New Guide for Estimating Natural Attenuation Rates for Light Non-Aqueous Phase Liquids in the subsurface

1. Scope

The proposed strategy for the estimation of attenuation rates of bulk LNAPL or individual constituents is generally divided into a set of five processes and pathways of measurement proxies such as CO2 flux at ground surface, vertical temperature profiles, gradients in soil gas and dissolved phase concentrations of LNAPL constituents, and changes in LNAPL composition. The scope of this standard is to also include considerations of the applicability of each of the five methods and available technologies based on site conditions with respect to the LNAPL source depth and location relative to the water table; soil stratigraphy; and ground surface condition. Key considerations in data collection and analysis include measurement locations and frequency; seasonal variability and extrapolation from discrete measurement locations to the LNAPL footprint; and refinement of field and calculation procedures in estimating the rate from the measured proxy due to natural attenuation of the LNAPL (i.e., correction for other anthropogenic or natural sources).

Keywords

NSZD, NAPL, Source Zone, Natural attenuation:

Rationale

A standardized approach for the estimation of the natural attenuation rates for LNAPL is needed for establishing a baseline metric for those involved in the remedial decision-making process. Despite the recent advances in published methods, there is a lack of systematic approach and refinement in data collection and interpretation for quantifying the spatially and temporally variable rates. Providing quality assurance in estimation of this metric will enable the assessment of active (more resource intensive) remediation systems as compared to passive remediation or monitoring of natural attenuation, as well as the remediation timeframe. This comparison, when performed through a standardized approach, informs the transition to more sustainable remedies through well-defined and transparent criteria.

The title and scope are in draft form and are under development within this ASTM Committee.

Details

Developed by Subcommittee: E50.04

Committee: E50

Staff Manager: Molly Lynyak

Work Item Status

Date Initiated: 04-27-2021

Technical Contact: Parisa Jourabchi