Derek McCoy, P.E. -
Owner & Principal Engineer
Derek has 29 years of engineering experience, 16 of which were progressively increasing responsibility in design, construction management, and contract administration for military roads, airfields, bridges, and other infrastructure projects. He also has seven (7) years of experience as a Project Engineer, Construction Manager, and Development Review Engineer, focusing on public roads, stormwater, utilities, and the approval/permitting process with state and local agencies.
He holds a Bachelor of Science in Civil Engineering from Colorado State University and is a licensed Professional Engineer (PE) in South Carolina, Georgia, Florida and Washington.
Carolyn Wiggen-McCoy - Chief of Operations
Carolyn grew up as a self-described "Air Force brat," moving frequently as a child before settling in Washington State for 35 years. She later returned to college full-time to study computer science, earning her degree while raising two daughters as a single mother — often working multiple jobs to support her family. That degree launched a new career in software engineering.
A few years ago, Carolyn, her husband, their youngest daughter, and their dog Tucker relocated to Charleston, SC, where they've since built a full and rewarding life. Her husband took a civil engineering consulting role that he loved so much he went on to found Coy Engineering Services.
At Coy Engineering Services, Carolyn oversees operations, bringing her technical background and steady leadership to the team.
Svjetlana Dragic - Technical Engineer & Drafting Manager
Svjetlana Dragic is a Technical Engineer and Drafting Manager with extensive experience in CAD design, technical drafting, and multidisciplinary engineering projects. She specializes in Civil 3D production for site development, grading, drainage, and subdivision projects, while coordinating drafting teams and ensuring drawing quality and consistency. She holds a Master’s Degree in Civil Engineering from the University of Novi Sad.
Anthony Guerrero, PE - Senior Project Engineer
Anthony has 8 years of progressively increasing responsibility in water resources, environmental engineering, civil design, and construction management. He has a Master’s in Civil Engineering from Saint Martin’s University, Lacey, WA, and is a licensed PE in Washington.
Mary Coastal Watkins - Project Engineer
Mary Coastal was born and raised on Goat Island in South Carolina, a small sea island only accessible by boat. Growing up, she commuted to and from school daily by boat. She graduated from Charleston County School of the Arts in 2020 majoring in Visual Arts. Throughout high school she worked at the Isle of Palms Marina fuel dock and for Barrier Island Eco Tours running a 50-foot, 50-passenger vessel. She earned her 25 Ton Master Captain's License by the age of 19, which is the youngest age allowable.
Mary Coastal graduated as a cadet from The Citadel Military College of South Carolina in 2024 majoring in Civil Engineering. She currently has her EIT in North and South Carolina and is working toward her PE. Since graduation, she has been a part of over 50 residential and commercial engineering projects dealing with permitting, site design, testing, and surveying.
In her free time, she is an artist at night and Captain on the weekends.
Becky Rieger - Senior Site Designer
Becky has 18 years of engineering design experience, including over ten (10) years as a Civil CAD designer and an Engineer Assistant specialising in permit assistance and code research. During the same period, she has over 15 years of experience in site and soil evaluations, septic designs, wetlands determinations, wetlands delineations, critical area studies, mapping, and site planning.
She has an Associate of Science in Geographic Information Science and Cartography, is licensed as an On-Site Wastewater Designer in Washington State, and is certified as a Wetlands Specialist by Portland State University.
Becky was an Engineer Technician during the time Derek McCoy worked at Hatton Godat Pantier in Olympia, WA, from November 2015 to October 2017.
Stephen Sersha - Senior Design Technician
Stephen has 17 years of Engineering Design experience, six (6) years of technical engineering experience with the US Army where he became experienced in drafting (AutoCAD), topographic surveying, construction surveying, design and quality assurance for various road, air field, and building development projects throughout the United States, three (3) years as Engineer Technician and Survey Crew Chief, and nine (9) years as Civil Engineering Designer and Survey Technician in residential and commercial developments across Washington and Idaho, where he produces site layouts, roadway design, site grading, storm drainage, sanitary sewer, potable water, irrigation, and much more.
He has an Associate of Science in Engineering from Itasca Community College, Itasca County, MN.
Stephen served in a Survey and Design Detachment at Joint Base Lewis-McChord, WA, where Derek McCoy was the Detachment Sergeant (Senior Engineer) from September 2013 to November 2015.
Tera De La Cerda - Art Director & Administrative Assistant
Tera De La Cerda joined Coy Engineering Services after relocating to Charleston, SC in 2025, where she continued the digital design degree she had begun earlier. She is currently a senior at Grand Canyon University, completing a Bachelor's degree in Digital Design with an emphasis in web design, graduating in 2027 with a 3.91 GPA, Dean's and President's List honors, and membership in the National Society for Collegiate Scholars.
At Coy Engineering Services, Tera manages the company website and provides administrative support to the team. She specializes in web design and brings a broader background in graphic design, creating visuals for both print and digital platforms.