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Still specializing in contaminated soil management… after all these years.

November 5, 2014

Terra-Petra is a full service environmental engineering firm that offers a variety of services. One service in particular that we have specialized in for over 15 years is contaminated soil management. We routinely conduct monitoring of soil during grading activities at construction sites in an effort to find any contamination that will need special handling. In our experience, this monitoring has become more commonplace in recent years. This phenomenon is due to several different contributing factors, one being the use of more conservative risk based assessment figures by governmental oversight agencies. Lowering the reporting limits/action levels for various VOC’s inversely increases the number of sites that are considered “contaminated.”

Soil monitoring is carried out in compliance with the Air Quality Management District’s (AQMD) Rule 1166 regulations.  This rule set as described by AQMD is to regulate the control of “Volatile Organic Compounds (VOC) from excavating, grading, handling and treating VOC-contaminated soil as a result of leakage from storage or transfer operations, accidental spillage, or other deposition.”  VOC’s are “any volatile compound of carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, ammonium carbonate, and exempt compounds”(AQMD).

Much of the contaminated soil monitoring that we conduct in the Southern California area is tied to the boom in oil well exploration around the turn of the century.   Using Los Angeles as an example you can see in the photo below how wooden oil derricks infested the landscape of the city. It was common for single family residences to have an oil derrick or two in their yards.  After this oil boom, derricks and oil wells were left abandoned with no regulations for how to properly plug and abandon the wells.  This in turn caused some VOC contamination in soil from the improper handling of oil, and petroleum reservoirs.

The Los Angeles City field east from the corner of First Street and Belmont Avenue, circa 1900 (Seaver Center). –Drilling Through Time

The Los Angeles City field east from the corner of First Street and Belmont Avenue, circa 1900 (Seaver Center). –Drilling Through Time

Terra-Petra’s certified inspectors conduct test methods using an organic vapor analyzer calibrated with hexane to test for toxic emissions. This test is done by placing a probe inlet at a distance no more than 3 inches from surface of excavated soil and moving the probe slowly across soil surface to find the maximum reading.  If maximum meter reading is above 50ppm, a soil mitigation plan is required to minimize VOC emissions to the atmosphere.  VOCs in excess of 50ppm are known to cause acute and chronic health effects in people. This is usually based on the level of exposure as well as length of time exposed to contaminated soil.

Any person having to grade soil that contains VOC will have to notify the Executive Officer at least 24 hours prior to excavating.  Monitoring will be done every 15 minutes commencing at the beginning of excavation or grading and recording of all VOC concentrations.  While handling VOC soil after excavating or grading at site shall segregate VOC contaminated soil from non-contaminated VOC.  For contaminated VOC soil, spray stockpiles with water or approved vapor suppressant and cover with plastic sheeting during any inactivity that last more than one hour.  This requires a daily inspection record for all covered VOC contaminated stockpiles. Any soil that has not been treated must be removed within 30 days from time of excavation.

If VOC concentrations are greater than 1000ppm, soil will have to be sprayed with water or a vapor suppressant.  If concentration reaches 1000ppm; place soil in sealed containers within 15 minutes. Person who treats VOC contaminated soil shall obtain a permit to operate treatment equipment’s. Any loading trucks that will transfer contaminated soil to the appropriate disposal facility must be clean of any soil in exterior and adequately tarp before leaving site to prevent soil spillage during transportation.  Typically, this is achieved by using rumble pads at all entries/exit locations and high-pressure hoses to wash the dirt and mud from trucks. This helps prevent any on or off-site VOC contaminated soil from spreading out into the open environment.

For further information about Terra-Petra’s contaminated soil management services, contact Justin Conaway at Terra-Petra – 213.458.0494.

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