Partner Engineering and Science, Inc. (Partner) was named the fifth largest firm on the 2014 LABJ Top Environmental Firms List. Published in November by the Los Angeles Business Journal, the list ranks the top 25 environmental companies in Los Angeles County by number of employees. The top 25 environmental firms represent over 2000 LA-based employees. Partner is widely recognized as the top provider of Phase I Environmental Site Assessments in the commercial real estate industry. Widely acknowledged by industry professionals, Partner delivers best-in-class Phase I Environmental Site Assessments.
This year’s ranking marks Partner’s first appearance in the top 5. The California presence of the Torrance-headquartered firm, which now includes 165 employees and 8 offices, has grown significantly in the last year. Joseph Derhake, President at Partner, explains that the demand for environmental due diligence services in Los Angeles is continuing to grow. “The LA commercial real estate market is performing well, and in this post-recession world, many borrowers and lenders are placing increased emphasis on thorough pre-transactional due diligence to better manage risks and liabilities,” he explains. “We’re hiring and devoting more resources to strong-performing regions like LA County to ensure we’re well equipped to meet these increased demands.”
In addition to being recognized as the fifth largest environmental firm, Partner was included on LABJ’s top 100 fastest growing businesses for 2014. “I’m hopeful that the combination of these two awards means Partner will continue to climb even closer to the top of the list over the next year!” said Derhake.

July 02, 2026
Adrienne Perez, an Environmental Due Diligence Consultant, joins as Technical Director for Agency Services in Partner Engineering and Science's environmental service line.

June 23, 2026
For commercial real estate owners, developers, and investors, the program offers a more flexible and efficient path to address contamination, particularly at lower-priority sites enrolled in voluntary cleanup.

June 24, 2026
Amid evolving and often uncertain federal regulations, state environmental agencies have increasingly taken the lead in developing policies to address PFAS.




