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Posts Tagged ‘soil’

Theoretical Gypsum Requirement (TGR) Models

Friday, July 6th, 2012

By John Ashworth,  ALS Environmental – Canada

ALS Environmental Lab TestingGypsum is often applied as an amendment to soils that exhibit a high sodium adsorption ratio (SAR).  The addition of gypsum can reduce a soil’s clay plasticity, thus improving drainage and ease of cultivation. Estimating the correct amount of gypsum required to remediate a particular site is an inexact science requiring experience and consideration of specific site history and conditions, but models described in the literature can produce theoretical estimates to provide guidance.  As a service to our clients, ALS now offers two theoretical calculations for gypsum requirement that are suited to two common categories of salt-impacted soil on the Canadian prairies.

Vapor Intrusion Investigations: Air Sampling Tips for Meeting Data Quality Objectives

Monday, September 26th, 2011

N. Dagnillo1, L. Hill2, A. Fortune3, A. Smith4, and S. Thompson2
1Trihydro Corporation, 3001 E. Pershing Blvd, Suite 115, Cheyenne, WY 82007
2Trihydro Corporation, 1537 Riverside Ave., Suite 101, Fort Collins, CO 80524
3Columbia Analytical Services, Inc., 2655 Park Center Drive, Suite A, Simi Valley, CA 93065
4Trihydro Corporation, 9460 Calle Milano, Atascadero, CA 93422

Vapor intrusion is a fate and transport process characterized by the upward movement of volatile chemicals from subsurface contamination (e.g., buried waste, contaminated groundwater) into overlying buildings. The potential for adverse human health effects from exposure to indoor air vapors has motivated private, state, and federal entities to develop guidance documents and protocols specific to the collection and analysis of soil vapor data.

Read more about Vapor Intrusion Investigations…

New and Revised Clean Water Act Methods Proposed

Thursday, September 23rd, 2010

New and Revised Clean Water Act Methods ProposedIn August 2010 the EPA issued a notice proposing new and revised analytical methods to be used under the Clean Water Act (CWA).

The proposed rule, entitled “Guidelines Establishing Test Procedures for the Analysis of Pollutants Under the Clean Water Act; Analysis and Sampling Procedures”, will affect numerous EPA Methods, ASTM Methods, Standard Methods, and alternative test methods.

EPA methods:

Read more about the proposed CWA Methods…

Reducing Errors through Multi-Increment Sampling

Wednesday, August 18th, 2010

By Gregory Salata, Ph.D.

Multi-Increment Sampling

The objective of environmental sampling is to quantify contamination at a given location. In situations where sample collection may result in discrete samples of a heterogeneous nature, results may be biased based on the particle size of each sub-aliquot collected at the site. One option to help reduce the errors associated with non-uniform sample composition is to use multi-increment sampling (MIS) to create a representative, homogeneous aliquot for analysis of analytes.

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Sequential Extraction Procedure

Tuesday, June 1st, 2010

By Pradeep Divvela, Project Chemist, Kelso, WA

ShakerSequential extraction is an analytical process that chemically leaches metals out of soil, sediment and sludge samples. The purpose of sequential “selective” extraction is to mimic the release of the selective metals into solution under various environmental conditions.

One commonly used sequential extraction procedure is designed to partition different trace metals based on their chemical nature.

The sequential extraction process is typically accomplished in four (4) steps using:

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