Start-Up Aerospace Design and Manufacturing Facility in Southern California

The client identified specific chemical contaminants of concern for various operations at the plant, identified operations for which noise was a concern, and assessed three office areas with indoor air quality complaints. Per client request, CSC provided pricing guidelines for performing the requested work. Following approval of the proposal, CSC scheduled the project and conducted the surveys for over a period of several days in 2018. The surveys encompassed a variety of operations and exposures. Inspections were conducted both visually, by observing the operations, and also analytically through sample testing. Some of the contaminants of concern tested were: methylene diisocyanate (MDI), hexavalent chromium in welding fumes, and respirable dust, petroleum distillates, iso-propyl alcohol (IPA) and acetone. In addition, CSC conducted noise dosimetry at various locations throughout the plant.

CSC conducted an indoor air quality (IAQ) survey in the modular office building.  Several employees had complained of health concerns specifically related to carbon dioxide (CO2), temperature and relative humidity. CSC investigated all offices by performing a visual inspection of the offices, and the heating, ventilation and air conditioning (“HVAC”) systems that serviced those spaces. In addition, CSC collected samples for measuring CO2 levels, temperature and relative humidity.

Schedule:  Approximately one week after receipt of the purchase order, CSC performed the assessment. CSC was on site for three days to complete the assessment, with the third day scheduled for approximately one week after the initial two days.  Laboratory results revealed employee exposures were above the permissible exposure limit for iron (Fe) and manganese (Mn) for the welding operation and 10 times above the permissible exposure level (PEL) for MDI.  CSC returned to the facility to perform detailed noise map and noise assessment for various operations.  CSC generated the report of findings within one week of receipt of the last set of laboratory results.  The project is 100% completed.

Project Outcome:  Respirable dust exposure was below the Cal OSHA PEL of 5 mg/m3 during the grinding, sanding and bag loading/unloading activities.

Welding metal fumes were above the PEL for Fe and Mn for employees performing welding activities.

MDI was non-detectable for areas outside the spray booth room. The concentration detected for the employee working in the spray booth during spraying operations was 10 times higher than the PEL. However, the employee was wearing a supplied air respirator which has an assigned protection factor of 1,000.  Monitoring showed that when the sample cassette was located inside the respirator hood, the concentration was below the laboratory analytical detection limit.

Petroleum distillate, IPA and acetone during Frekote™ application, solvent use and surface prep activities was well below their respective PELs.

Based on the findings of the air testing, CSC recommended the following:

  1. Employees performing welding activities should wear at least a half face respirator with P100 cartridges.
  2. Employees should continue wearing supplied air respirators working inside the spray booth room during MDI foam spraying. 
  3. Employees should wait at least 20 minutes after the MDI foam spray operation has ended to re-enter the spray booth room.

CSC identified specific operations and areas of the plant for which noise exposures exceed either the action level or the permissible exposure level for noise, and made recommendations for the use of hearing protection in implementation of a hearing protection program. For operations with exposures above the PEL, CSC also calculated the minimum noise reduction rating for hearing protectors to be used for operations exceeding the PEL, taking into account the de-rating factors recommended by the National Institute for Occupational Safety and Health (“NIOSH”).

For the indoor air quality survey, CSC determined the following:

This study was conducted to investigate reported employee complaints regarding a potentially air quality within the modular building.  Although the overall condition of the modular building appeared good, the CO2 measurements indicated a need to increase the fresh air supply to the area. Additionally, HVAC maintenance was seen to be less than adequate in that there were indications of past condensation pooling in the condensation pan and the air filters were loaded and needed changing.  Information regarding the HVAC units designed air turnover rate and were not available at the time of this investigation.  In addition, a written preventive maintenance plan was not available at the time of this investigation.  Therefore the following recommendations were made:

  • Recommendation 1: Increase fresh air flow into the structure.
  • Recommendation 2: Ensure an updated written HVAC PM program is in place and is functional for the facility and that the modular buildings are included in the program. It is important to have current records and a written  maintenance plan per Cal/OSHA Title 8, Section 5142.
  • Recommendation 2 (a): In order to ensure that the written plan is adequate to keep the filters changed and prevent water pooling in the condensation pans, conduct occasional spot checks of the filters and pan.
  • Recommendation 3: Ensure that site maintenance personnel/contractors have readily available information on the HVAC units.
  • Recommendation 4:  Increase frequency of cleaning procedures.

CSC was also engaged by this client to provide assistance in obtaining NPDES permits for storm water compliance and for hazardous materials waste management.


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