Hamp, Mathews, and Associates

Rosanne has been supporting the Data Analysis and Visualization Team at Hamp, Mathews, & Associates as a Data Base Specialist since 2004. She credits the love of her job to the amazing people she gets to work with. Prior to coming onboard with HMA, Rosanne worked for many years in an analytical laboratory, she was very excited to move to the ‘other side’ and get a glimpse into what the scientific data generated was used for in real life situations. Rosanne has a passion for antiques and anything ‘unusual’, in her free time you might find her antiquing or frequenting flea markets to sell at an auction house that she co-owns. She has an adorable puppy named Bear that gets to travel with her anywhere and everywhere! Rosanne wears many hats with HMA, often focusing on tending to the needs of her colleagues; she is a valuable team member at HMA.

MEET OUr team

Abigail Varner

Senior Engineer

Alan Mathews

President & CFO

Autumn Parish


Thomas Fleet

Senior Geologist/Project Manager

Thomas joined Hamp, Mathews, and Associates in May of 2014 and (as a Senior Geologist) is a prominent associate on the Remediation Team. He values his role as a key member of a collaborative team of problem solvers; able to create real solutions out of often very complex issues. Since Thomas can remember he has had a passion for the outdoors, and to make a positive impact where he can. Soon after his first geology class in college, he decided to make a living protecting the environment. Growing up, one of Thomas’s fondest memories was salmon fishing in Ludington with his dad. He continues to share this lifelong hobby with his dad and brother, and he has recently taken on the challenge of learning to fly fish. Thomas is blessed with two beautiful daughters; whom he credits their kindness and beauty all to their mom. Fun fact about Thomas is that he is learning to play acoustic guitar! Although he had a music background in high school, he feels this is rewarding on a much different level. He enjoys getting to recharge in northern Michigan with friends and family, especially in Marquette during an annual music festival. He is a pivotal member of the HMA team, and we are grateful for the authentic and dedicated approach that Thomas delivers each day.

Dan Rathka

Senior Scientist

Doug Spencer

vapor mitigation specialist & operations manager/Project Manager

Doug has been a Vapor Mitigation Specialist and Operations Manager on the VIAP Team with Hamp, Mathews, and Associates since 2017. He enjoys the fast-paced nature of the environmental field, working outside, and the hands-on approach to problem solving. Doug is a proud husband and father, and he enjoys traveling with his wife and their three children to the Outer Banks and Northern Michigan. In his free time, you can find Doug fishing, camping, woodworking, or doing home remodeling projects. Fun facts about Doug, he started all four years on the lacrosse team at Calvin College and is known as the ‘resident expert’ in native plants, with over 87 different species at his home. Doug chose the environmental consulting industry so he could “have an impact on protecting and improving the ecological health of our communities”. Doug plays a vital role in navigating environmental challenges, getting involved in protecting the health of our communities through various charitable efforts, and incorporating new technologies at HMA, and we are thankful for the knowledge and fortitude that he brings to the team.

Dylan Harter

Staff Geologist

Dylan has been a Geologist and respected member of the Data Acquisition Team with Hamp, Mathews, and Associates since 2018 and he enjoys the complexities that the environmental consulting industry has to offer. He has always been interested in STEM academic disciplines and having the opportunity to work on a wide range of projects at HMA aligns perfectly. In his free time Dylan enjoys spending time outdoors running or biking, traveling to the Rocky Mountains and Alaska, as well as tinkering with his Jeep that he refurbished. Dylan graduated with a degree in Geology in 2021 from Michigan State University and is a proud husband and owner of two naughty cats. HMA is grateful for the energy and excitement that he brings each day, and his drive to explore innovative, creative concepts with the team.

Holly Petroff

Office Manager & integrator

Holly has been an office manager and integrator with Hamp, Mathews & Associates since March of 2020. She is extremely grateful for the opportunity to work with such insightful experts in the field of environmental science. Though she is not a scientist, Holly works to anticipate the highest and best potential for not only HMA as a whole, but staff on an individual level, encouraging everyone to focus on their passions within the industry. She works with the leadership team to evaluate the professional environment, predict potential hurdles, and facilitate structure within the organization. Holly and her husband have raised an active, blended family of seven (7) children, and she believes that juggling this busy household has helped her tremendously in her career. In her free time, Holly enjoys Yoga, time with family, and traveling. Fun fact about Holly, she is a music lover (all genres); one of her previous clients was Lee Oskar from the band War and she has an engraved harmonica from him!

Jake Kottke

Senior environmental scientist/Project Manager

Jennifer Weaver

Project Accountant

Joel Parker

Principal Engineer & visionary

Jeff Crum

vapor intrusion/Project Manager

Jeff has been a Senior Toxicologist and Vapor Intrusion Specialist with Hamp, Mathews, & Associates since 2004. He enjoys working with a team of top shelf, yet humble practitioners that communicate comprehensive, “science-based” environmental solutions to clients and regulators. Jeff has been practicing and studying vapor intrusion risk assessment and mitigation strategies for 25 years and feels that each opportunity is as exciting as the first. Jeffs initial interest in Environmental Toxicology surfaced when he was a student assistant for the Michigan DNR (pre-DEQ and EGLE). It was there that he recognized the impact that environmental contamination can have on fish and wildlife (which was his bachelor’s degree) and eventually lead him to the field of environmental toxicology. Jeff is a proud family man and enjoys spending time and traveling with his wife and two adult children, especially to the Appalachian Mountains. In his free time Jeff enjoys golfing (often competitively) with friends and family, and notes that his wife is ‘quite good’. Fun fact about Jeff is that he met Nick Saban while on vacation in Florida. Jeff plays a vital, lead role at HMA and we are grateful for his industry expertise and the connections he has built throughout his career. His thoughtfulness and respect that he shows his peers accentuate his career attributes.

Matt D'Addona


Matt has played an essential role as a Geologist with Hamp, Mathews, and Associates since 2018. He enjoys learning about the challenges and complexities that the environmental industry present, affording him the qualifications to contribute to solving various problems. Matt became interested in geology after an introductory course in college, he then went on to earn a Bachelor of Science, with a Concentration in Professional Geology from Eastern Michigan University. Fun fact about Matt is that he can still remember a time before the internet became a household convenience. In his free time, you might find Matt learning more about the nature of the Earth System, spending time with friends and family, and traveling to the Catskill Mountains of New York. Matt is a critical member of the team and has a wonderful, quirky sense of humor, and is always good for a laugh. We are grateful for the insight and synergetic approach that Matt brings to work each day.

Keri Ryan

Environmental Scientist

Keri joined Hamp, Mathews, and Associates and the Data Acquisition Team in June of 2022. Keri obtained her degree in Environmental Economics and Management in the Spring of 2022 from Michigan State University. Keri is very excited about beginning her career as an Environmental Scientist in a field she sparked a passion for in her first year of college. Keri is excited about the many facets of environmental consulting as well as the problem-solving process that prefaces finding measurable solutions for the unique challenges of our customers. Keri credits the pairing of field work and expert mentorship with being the most interesting and valuable on-the-job training pieces. In her spare time, Keri is an avid fan of Michigan State University Football and enjoys cooking, and anything to do with water like swimming and boating. Florida is one of her favorite places to visit due to her love of the ocean. Fun fact about Keri, she has immediate family that resides in the Keweenaw Peninsula of Upper Michigan and grew up swimming in the cold waters of Lake Superior. 

Steve Zayko

Senior Engineer/Project Manager

Steve joined Hamp, Mathews, and Associates in November of 2020 as Senior Engineer on the VIAP Team with almost 30 years of experience spanning the globe. Steve specializes in many environmental practice areas adding substantial value to project collaboration. Steve credits his love of the outdoors and helping others as steppingstones to his longevity as an Environmental Consultant. In his free time, you might find Steve backpacking across Canada or the US or dabbling in wildlife photography. Steve is also a proud husband, dad, and Eagle Scout and was excited to join HMA to “collaborate with a great group of people with varying backgrounds and skills”. HMA appreciates the knowledge and mentorship that Steve brings to work each day, and we are grateful that he joined our team.

Brett Kamphouse

Environmental Scientist

Brett joined Hamp, Mathews, & Associates in May of 2022 as an Environmental Scientist on the Data Acquisition Team shortly after completing his bachelor’s degree in environmental Geosciences from Michigan State University. Brett credits his decision to explore environmental science in college to his love of science and the outdoors. Brett adds that working at HMA affords him the ability to learn real-life problem-solving skills in real life situations and he enjoys working with an amazing group of people. Brett was Academic Allstate in Football and Baseball and is still an avid sports fan. He enjoys watching sports, playing basketball, snowboarding, or reading in his spare time. Although he has never been, one of Brett’s bucket list adventures would be a trip to Mt. Everest. Brett brings a solid work ethic to our team, he is always eager to learn new skills, and we are thrilled that he came on board!

Ryann Scott

Due Diligence Specialist/Project Manager

Ted LaMarre

Senior Engineer/Project Manager

April Hehir

Due Diligence Specialist/Project Manager

Jon Thorold

Staff Geologist

Kyle Kennedy

Environmental Scientist

Kyle Shinabarker

CAD Specialist

Lisa Zuber

Administrative Assistant

Pam Wheeler

Due Diligence Specialist/Project Manager

Luke Hixson

Senior Environmental Scientist