Explorations in environmental science


We feel so privileged when we get a chance to meet the environmental professionals at Horsley Witten, the Cape’s leading environmental consulting firm, to learn more about the projects they are working on locally and abroad, and to get their insight on the leading environmental issues facing the region. This time, we check in with Mike Demanche whose connection to nature lead him to the field of environmental science and his connection to the Cape lead him to carry out his passions at Horsley Witten.

Can you tell us a little bit about your background? What drew you to the environmental field and how did you end up on Cape Cod with Horsley Witten?

I grew up in Mashpee and graduated from Mashpee High School. As a youth I was really into the outdoors. I was introduced to hiking and camping through Boy Scouting, and as I became older and more independent, I would go out to the mountains with my friends. At that time, I don’t think I really expected my interest in the outdoors to turn into an education or a career, but eventually it did lead me to where I am now (albeit slightly indirectly).

After I graduated from Mashpee and went to college at Brown University, I started down a pre-medicine/ biology track but quickly realized that wasn’t where I saw myself - it just wasn’t my passion. After a year studying in that direction, I decided to take a semester off school to backpack with some of my friends from Mashpee. We opted to thru-hike the Appalachian Trail and spent five months completing that journey. My experience on the trail led to a real interest in environmental science. The AT winds its way through pristine old-growth forests and over spectacular mountains, but also along highways, through towns, and past industrial sites. We crossed rivers that were contaminated and undrinkable, diverted around fenced-in waste clean-up sites. I remember one instance near the Hudson river where a sign told us before the smog you could regularly see the New York City skyline… with the current smog that view was now visible at most once per year.


When I got back to school, I had found a purpose in understanding Earth systems and how humans interact with our environment. I took geology and environmental science courses and chose to pursue a degree in geology. The next year I became an intern with Horsley Witten Group after meeting my future boss at an alumni event. It helped to have grown up right down the road! After that I spent the next summer doing research in Narragansett Bay before coming back to Horsley Witten full time following graduation.

Your title is Environmental Scientist – what are your primary responsibilities?

As an Environmental Scientist, I get to be involved in many of the varied tasks that Horsley Witten performs. My favorite part of my job (when the weather is nice) is to get out of the office and do field work - usually groundwater sampling, groundwater monitoring, or surveying for our engineering and construction projects. I also like getting out and working with our planners at public meetings. It’s a little different than my other field work, but it’s fun to be on the public-facing side of things and again, out of the office!

When I do have to stay inside and do office work, I still get to be involved in a lot of interesting projects. I’ve used groundwater data to build models of aquifer systems, which can be used to evaluate the hydrologic effects of drinking water withdrawals and wastewater discharges. I write reports about the results of field sampling efforts and do a lot of interesting data analysis.

Give us an example of a recent project you worked on, and how it fostered environmental sustainability.

Recently I’ve been in the field collecting topographic and bathymetric survey data to support two dam removal-related projects we’ve taken on. In one case, this involved performing a survey after the dam had already been removed in order understand the effects of the dam removal on areas that were once under water. In the other case, the dam hasn’t been removed yet, and I was out collecting existing conditions data to inform a conceptual design for dam removal. The data I collected will inform hydrologic and hydraulic modeling, which we’ll use to understand the impacts of dam removal on sediment dynamics, river hydraulics, and any potential impacts to existing infrastructure. The modeling will also inform an evaluation of options to replace an undersized culvert upstream from the dam. Our designs will account for factors like the impact of construction equipment on the surrounding landscape, sediment behind the dam that will be mobilized when the dam is removed, replacing a culvert under a road near the site, and beaver dams in the same neighborhood.

2 IMG_9452-edit.JPG

Removing old dams can foster environmental sustainability in several ways. Put most simply, removing the dam restores the natural course and hydraulic regime of the river, and returns the impounded area from slow or no-flow conditions to the natural rate of the river. The increased flow rate will result in naturalized sediment transport from upstream to downstream and improved water quality upstream of the dam. Restoring and maintaining wetlands near the site increases the ability of the system to mitigate flooding risk. Removing the physical barrier of the river allows fish and other aquatic organisms to migrate upstream and downstream along the river. Finally, an older dam may be more susceptible to failure and removal increases the safety of those downstream. 

There are clearly a lot of factors to consider in a dam removal design or review project. We keep all these factors in mind throughout the entire project from data gathering in the field to design in the office. These types of projects bring together many of the areas in which HW operates - wetlands science, hydrology, engineering, and community involvement.

Why do you think the work Horsley Witten does is important?

Horsley Witten does such a variety of tasks it would be hard to answer why they’re all important. There are two different aspects of how HW works that I think will answer the question well:

First, HW projects range in scale from local to national. On any given day I can be involved in projects which stay within the Town of Sandwich or reach out to federal agencies on national issues. Second, because HW is involved in such a variety of work, we’re able to approach problems in house in a well-rounded fashion. We have scientists, planners, engineers all working in the same space and bringing their perspective to the tasks at hand. These different foci aren’t relegated to specific departments, so most teams within the company involve colleagues with varied backgrounds.

This breadth of project and personnel creates a group with experience solving all sorts of different problems and looking at problems from all sorts of different angles. When we take on a task, we can look at it through a variety of lenses (that of the planner, the scientist, the engineer) without having to go outside the company. I think this yields a good product for everything we do. All our different areas of expertise are closely linked, and nothing gets done without being informed by another point of view.

In your opinion, what is the most pressing environmental issue facing Cape Cod?

Wastewater management is huge. Development on the Cape is spread out and grew in such a way that each house has its own septic system. While septic systems do OK at treating wastewater, they don’t do everything we need them to (i.e. removing nutrients). Our biggest asset is our natural beauty; our harbors, rivers, and estuaries. We need to think for the future and manage our waste so that we don’t ruin our best resource.

How do you think we as a community can address it?

It’s going to take cooperative approach to address the wastewater problem because it involves science, policy, and economics. The infrastructure is going to have a price tag, and we need to make sure all the different communities and stakeholders involved are represented through the process to ensure that the costs and benefits are distributed equitably. I think designing based on the location of wastewater sources and the underlying topography will be critical in managing the overall costs. Advanced cluster-type treatment systems distributed throughout the region decrease the amount of sewerage installation and operation. The problem is designing this way might not align perfectly with existing town lines and other boundaries, which can make it hard to decide who pays for and to hold communities accountable for doing their part.


Horsley Witten Group is an engineering and environmental consulting firm founded on the principles of sustainable water resource protection. Their mission since 1988 has been the conservation, preservation and protection of our most valuable natural resources.