CSC conducted soil sampling investigations at several sites impacted by the Woolsey Fire near Malibu, California. Various metals and other toxic materials can accumulate at elevated levels in shallow soil resulting from burning of houses and other structures. Contaminants often include lead from paint, vanadium from reinforcing steel components and arsenic or chromium from pressure treated wood.

Sampling was conducted by field sampling professionals following protocols set forth by the County of Los Angeles in its fire cleanup guidance document. The main variable in the process is determination of number of samples. The statistically valid number of samples is dependent upon the size of the ash footprint and is commonly coincident with the location of the eaves of the burned structure. Building foundations may be reused subject to testing by a structural engineer but are typically removed prior to regrading of the lot.

Five-part composite samples were collected around each predetermined sampling location. Samples were collected using stainless steel trowels at a depth of zero to three inches below ground surface (bgs). Samples were analyzed for the 17 listed metals identified in the California Title 22 Code of Regulations. Upon receipt of laboratory results, CSC evaluated the reported concentrations by comparing them with the screening levels contained in the County guidance document.

If sample concentrations exceeded screening levels, CSC provided recommendations to mitigate the condition. Actions taken typically included removing additional soil or in many cases simply removing excess ash residue. The areas were then resampled by CSC to confirm that metal contamination had been sufficiently addressed. For some metals, especially arsenic, natural background commonly exceeds the published screening level. In which case, CSC collected additional samples outside the ash footprint to establish background levels and/or used background levels found at other sites in the area. CSC provided technical memorandum to the owner documenting the investigation procedures and results. Owners were required to include the CSC technical memorandum in the rebuilding permit application package submitted to the County for final approval.

We have been more than pleased with the service provided by Clark Seif Clark Environmental. This is our second contract with them and their professionalism is top notch. I can only hope they are the successful bidder on our next contract as well.

Jim B.
Chief of Plant Operations II

Just want to say Thank You.
Your lunch presentation was nothing less than awesome. Your professionalism, enthusiasm, and knowledge energized the class. We look forward to a continued relationship with you and your organization. Thanks again,


I just wanted to take a moment to say Thank You for on excellent presentation on Saturday.
My technicians and I were all very impressed by what we learned, and I received some very positive feedback from the other offices in attendance. Being in the water damage business, we are frequently faced questions about mold growth from water damage customers, insurance personnel and property managers. Your presentation, visual aids and handouts were well planned and targeted to our particular interests. I think we can now address the topic with a greater sense of confidence (and a little less guesswork!). I am sending copies of your presentation packet to everyone who attended along with request for feedback. Thank you again for a well done presentation. I look forward to working with you on future projects.


Wanted to take a few minutes to express our "thanks" for the wonderful presentation that Derrick Denis gave at our office meeting last month.
We had over twenty agents in attendance and they were all very impressed with no only the knowledge, but the informative way Derrick presented the material. The Mold Disclosure Issue is one of the most confusing that we as real estate practitioners have had to deal with in a number of years. Derrick made the confusion somewhat less on our part and gave us all a better understanding if just how we should present this problem to our clients. Again, thank you for having such a wonderful person representing your company. We would not hesitate to use or recommend your firm to our clients.


Thank you again for being part of the Los Angeles County East Chapter (LACE) luncheon program last week.
We greatly appreciated your understanding of our audience and what they needed to know. Both your presentation and responses to the participants questions were right on target.


COVID-19: Assisting Clients with Strategies for the New Realities