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About Our Firm

Gary Castle and Associates is a small surveying company founded in 1988. Mr. Castle has been practicing in Frederick County and surrounding areas since 1964. The company and its employees have a wide range of experience in all phases of surveying as well as civil engineering. Gary and Tom McEntire are both Licensed Surveyors and our combined staff has over 110 years of surveying experience and is licensed to practice in Maryland and Ohio. The firm uses state of the art surveying equipment including robotic total station instruments, RTK (Real Time Kinematic) utilizing both United States and Russian global positioning system satellites for added precision, and Terramodel software for office computing and drafting.

When you choose Gary Castle & Asociates, you're hiring our courteous, friendly, and experienced land surveyors with a proven track record to take your project from inception to completion. Serving individuals, small businesses, and custom builders throughout Central Maryland.

About Our Staff

  • Gary W. Castle, R.P.L.S.Maryland Property
    Line Surveyor #204
  • Tom McEntire,
    R.P.L.S., P.S.
    Maryland Property
    Line Surveyor #488

    Ohio PLS #S6281
  • Richard W. CastleSenior Survey Technician

Gary Wayne Castle


Gary has over 47 years of surveying experience in the central Maryland area, Pennsylvania, Virginia, and West Virginia, involving all aspects of project management, agency coordination, subdivision and site plan preparation, and expert testimony in land disputes. Gary is recognized as an expert witness in Frederick and Washington County Circuit Courts. Gary also provides professional consultations for individuals contemplating residential or commercial development or subdivision. Surveyors must wear many hats to take a project from conception to completion. Gary has worn all of these many hats. He is a former member of the American Congress of Surveying and Mapping and the National Society of Professional Surveyors. He served on the state board of directors for the Maryland Society of Surveyors from 1992 to 1994. Gary helped organize the Mason Dixon Line Preservation Partnership, and has acted as treasurer from its inception in 1993 to present. He was a civilan ambassador of the United States Friendship Force, to the Director of Land Use and Planning in Moscow, Russia, 1994. Gary has also served on the Survey Product Recommendation Board of Wild Herrburg, Wild Leitz USA, Inc.

Thomas Scott McEntire



Tom has more than 45 years of surveying experience in Pennsylvania, Ohio, Michigan, and Maryland. Tom's Midwest experience involved highway, bridge, manufacturing plant, and utility construction surveying. Tom also performed boundary, topographic, and utility surveys, some of which involved the United States Public Land System (sectionalized lands.) Since moving to Maryland in 1984, Tom spent 8 years managing up to five survey crews and supporting staff for a local consulting firm. In 1992, Tom joined Gary Castle and Associates and has been involved in all aspects of surveying and mapping, from field surveys to computing, drafting, reviewing final plats and site plans, project management, and agency and client coordination. Whatever the task, Tom will fill in as needed. Hands-on involvement with our clients and governing agencies is what Gary Castle and Associates strives for with projects large or small.

Richard William Castle


Richard (Rick) has over 23 years of survey experience in the central Maryland area. Rick started working with his father part time, running the instrument, when he was 13. Rick worked full time on the field survey crew under the direct supervision of either Tom or Gary from 1993 to 2002. Rick has been involved in field survey work for boudary, topographic and utility surveys, FAA tower certifications, FEMA evaluation certificates, construction layout of buildings, roads, long utility lines, and site improvements. Since 2002, Rick has been instrumental in managing our software needs and performs all of our survey computations and CADD drawings necessary to produce our final products. Using our survey equipment, robotic or RTK GPS, Rick has performed field to finish design surveys for various engineer / architect clients. Rick, as well as Tom and Gary, carries a security clearance that allows working at various high level federal and state government agencies.