Thew Associates PE-LS, PLLC is a land and hydrographic surveying and mapping firm founded by Spencer F. Thew, PE-LS in 1972, and has transitioned to its second generation as the daily operations of the firm have been managed by James S. Thew, PLS since 1994. The firm continues to operate under the ownership of Jim (90%) and Spence (10%).

The firm operated as a sole proprietorship (Spencer F. Thew, PE-LS) from 1972 through 1999 and was affiliated with Atlantic Testing Laboratories, Limited (ATL) from 1972 through 2007, which was also founded by Spence in 1967.

In 2007, Spence put away his transit, steel tape, and slide rule to pursue other interests in his retirement years; however, we continue to tap his 50 plus years of surveying, engineering, and construction experience, as the advice he offers and the perspective he provides are always valuable.

Spence has Bachelors of Science and Masters of Science degrees from Clarkson University in Civil Engineering and Geotechnical Engineering, respectively. He obtained his surveying experience working under the supervision of Spencer J. Johnston, PLS (No. 024084) in the Adirondack Mountains and Champlain Valley of New York, and under the direction of Harry Lord in St. Lawrence County.

Spence became a licensed Professional Engineer and Land Surveyor in 1967 and 1972, respectively. He seized upon the need for high quality topographic, bathymetric, utility, and boundary surveying and mapping, and construction surveying and as-built mapping for the architectural, engineering, and construction industries throughout Central and Northern New York.

Jim has a Bachelors of Science degree in Surveying Engineering from the University of Maine (Orono) and became a Licensed Land Surveyor in 1996. He obtained his practical surveying experience working under the supervision of Spence (Dad), and remembers being “Dad’s rodman” at the tender age of six (there was no enforcement of child labor laws back in the early 1970’s). From 1997 through 2005, Jim managed ATL’s Drilling and Geotechnical Engineering Division responsible for the execution of land and water based geotechnical and environmental investigations. In 2006, he decided that he would focus on growing the survey company and subsequently resigned his position with ATL. It has proven to be a very satisfying decision.

Since our modest inception in 1972, Thew Associates PE-LS, PLLC has prospered to become a 20 person technical services firm providing land and hydrographic surveying and mapping, performing ASCE Quality Level C, B, and A subsurface utility investigations, performing concrete imaging utilizing ground penetrating radar (GPR), and performing sediment sampling and analysis utilizing vibracore technology.

In 2010, Jim co-founded Subsurface Utility Imaging, LLC with Robert H. Korosec, PLS (Operations Manager with Thew Associates PE-LS, PLLC) to brand the subsurface utility offerings the firm has provided over the previous 20 years. Our rigorous internal and external subsurface utility training has given our staff the ability to confidently perform ASCE Quality Level B and A subsurface utility investigations.

Thew Associates PE-LS, PLLC currently has five professional land surveyors on staff, and continually encourages our younger staff to pursue professional licensure.

We strive to be responsive to our client’s needs, to provide a high quality deliverable in a timely manner, and to challenge our staff to continually improve both technically and professionally. It is our mission to ensure our staff has the tools and resources to continue to operate this company into perpetuity.


Land Surveying


Hydrographic Surveying


Subsurface Utility Engineering

Laser Scanning

3D Laser Scanning Services


Drone Services


6431 US Hwy 11
Canton, NY 13617

Phone: 315-386-2776 
Fax: 315-386-1012


9478 River Road
Marcy, NY 13403

Phone: 315-733-7278
Fax: 315-797-1957

Saranac Lake

135 Broadway
Saranac Lake, NY 12983

Phone: 315-386-2776


135 Old Cove Rd, Suite 20
Liverpool, NY 13039

Phone: 315-244-2151

Thew Associates Land Surveyors
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