Robert M. Edgar
Director, Site Assessment - Remedial Investigatory Services

Published in Mid Atlantic Real Estate Journal, Sept. 2009

Farms are cornerstones of American tradition, but in our quest for developable land, they are increasingly being swept away in the changing tide from an agricultural economy to residential development.  Unfortunately for today’s property developers and owners, one of those historical connections is the widespread application of pesticides which persist long after the crops are gone.

Arsenic based pesticides, which include lead arsenate are commonly used and have been in use for hundreds of years.  Following World War II, chemical companies and agricultural experts promoted the use of synthetic chemicals like dichloro-diphenyl-trichloroethane (DDT) and dieldrin as substitutes for lead arsenate. 

Unfortunately, many pesticides are not easily broken down by weathering.  As a result pesticides tend to persist for decades after their application, and it is not uncommon to find residual concentrations of DDT, its breakdown products, as well as arsenic and lead within soils at the sites of former farmlands.  This situation can be further complicated by the fact that these pesticides were often applied using aerial spraying, resulting in a pesticide impacted area that can extend beyond the “footprint” of the farm.

Because of their persistence in the environment, and their relatively high toxicity, the synthetic pesticides typically have much lower cleanup standards.  In some cases the difference is more than an order of magnitude.  This lower standard means more frequent and larger impacted areas that require investigation and remediation. 

When performed properly, environmental due diligence investigations such as Phase I Environmental Site Assessments, performed for proactive buyers, banks, and developers, can uncover past agricultural uses that have the potential for pesticide use.  When past agricultural use is identified, confirmatory soil testing for pesticides is performed.

State and Federal environmental agencies are becoming increasingly aware of the potential environmental impacts caused by former agricultural use, and several states, including Hawaii, Washington, Michigan and New Jersey, have drafted guidance documents and regulations governing the investigation and remediation of residual pesticide impacts.

We now know that it is important to conduct a thorough investigation of former agricultural use properties.  If an area of contamination is missed during the initial investigation, future property redevelopment activities can result in the unintentional distribution of pesticide impacted soils on the property in question, and offsite, if soils are removed from the property.  Since lead and arsenic are always present at some background level, it is important that a consultant with relevant experience be utilized to distinguish naturally occurring metals concentrations from those attributable to pesticide applications.

There is hope for property owners and developers dealing with residual pesticide impacts.  In a departure from typical environmental policy, some states have given approval of remedial methods known as soil blending.  Calculations are performed to determine the quantity of clean materials necessary to blend the contaminants to levels below regulatory concern.  Clean soils used in blending can consist of either onsite material that has been tested and shown to contain contaminant concentrations below regulatory guidelines, or imported clean and/or virgin material.  Soil blending can either be accomplished using backhoes and front end loaders, or, in the case of larger and deeper impacted areas, specialized soil mixing equipment is used.  In either case, because soil blending can be performed during site redevelopment, often with equipment already available during redevelopment activities, it is increasingly becoming a part of the remedial strategy at former farmland sites.

Remedial costs, future site use, and the location, concentration, and extent of pesticide impacts are all considered in picking an appropriate remedial option.  With the proper guidance, developers and property owners can once again enjoy the financial fruits of their labor.

Mr. Edgar is with EWMA’s Headquarters Office in Parsippany, NJ.  He specializes in environmental assessments and remediation.  For additional information or to discuss your concerns please contact Mr. Edgar at 800-969-3159 ext. 159 or visit our website at www.ewma.com.