Month: March 2021

Vernal Pools: Springing to life!

hand holding eggs over water

Here we are, it’s March! You made it through the cold dark winter! The days are getting longer, the sunlight is feeling warmer, and maybe this year more than ever, many of us are feeling the push to move more, get outside, feel that sun on our faces. To be sure, there will be one more snowy day that will surprise us – and is it really a surprise when it happens every year? – but the idea that winter is behind us lifts our human spirits.

The wildlife around us are feeling it too; they are awakening from their winter hide-aways and are starting to move around, looking for food and mates. The extra daylight, warmer ground temperatures and spring rains trigger movement for a special group of animals that use temporary vernal pool habitat to complete their life cycles. If you hear the high-pitched call of the spring peepers, or the quacking sound of a wood frog chorus, chances are you are near a vernal pool. 

What is a vernal pool? Vernal pools are seasonal bodies of water that form only in the spring in shallow depressions that occur throughout the glaciated region of eastern North America, including the Great Lakes and New England. One key factor that separates vernal pools from any old puddle that we see in the spring as snow melts, groundwater rises and rain collects in low places is the lack of an outlet or connection to running water, such as a stream, brook or creek. This specific difference allows for a special habitat that lacks fish, where certain amphibians, insects and other invertebrates can lay their eggs and complete a portion of their life cycle. The other important factor in identifying a vernal pool is that while they may stay on the landscape for at least two months, vernal pools are generally ephemeral, or temporary, so as spring rains pass and temperatures rise, the pool will disappear. This drying also prevents fish from establishing permanent populations. You may walk by a vernal pool on your summer day hikes and not notice this very special habitat.

Vernal pools vary in size and can be surrounded by wetlands, swamps or dry land, depending on where they sit in the regional landscape. In some cases, deeper sections can look like a pond and have vegetation reflective of that such as water lilies or grasses, while others may be only a few inches deep and have a layer of leaves or moss at the bottom. While they are most often found in forested areas, they can also occur in fields or roadsides. Some pools can fill in the autumn or winter and remain ice-covered until the magical combination of spring weather allows for ice to thaw and the organisms to come out, while others remain dry through summer, fall and winter and are only apparent in the spring.

Why are vernal pools protected? One reason is because the unique set of species that depend on these pools cannot exist anywhere else, and they in turn play a role in the ecological life cycle that supports all life on this planet. Vernal pools are considered a type of wetland or water body, and in New England, are regulated and protected at the federal level by the US Army Corps of Engineers. Each state also has regulations specific to vernal pool identification and protection, and in Maine and Massachusetts, mapping and recordation as well. In New Hampshire, vernal pools are regulated and protected per the state wetland rules Env-Wt and are defined under Chapter 100. Vernal pool identification is based on physical factors as well as the primary and secondary indicators, which are specific species that only use vernal pools as habitat.

Vernal pools come to life in different times of year within New England, as early as late February along the Rhode Island and Connecticut coasts, while upper Vermont and Maine will not see vernal pool activity until mid-April. Here in New Hampshire, we start to see amphibian migration on warm rainy nights starting in late March and extending through late May.  

Vernal pool organisms also rely on the undisturbed upland surrounding the pool, what is often called the pool envelope. Vernal pool amphibians spend most of the year in the upland discretely feeding, hibernating, and preparing to breed in the spring. Protection of uplands around vernal pools from development or alteration is an important part of the regulatory and permitting process, which is why identifying vernal pools during the correct time of year is an important part of planning for any development type of project, including not only residential and commercial development, but also infrastructure projects such as roads and bridges.

Hoyle, Tanner’s Certified Wetland Scientist, Joanne Theriault, has the training and experience to investigate your site for vernal pools – and given the length of time spent indoors this winter assisting her children with remote learning, she is eager to get outdoors again! Reach out to her with questions!

Sorting nearly 6,000 Pounds of Food for the NH Food Bank

The Mission

The New Hampshire Food Bank is the only operating food bank in the state, consistently supplying more than 400 hunger relief agencies with non-perishable food items, fresh produce and meats. Every year, millions of pounds of food and meals are collected and distributed to families in our communities by the generous volunteers and staff at the facility. This year, our marketing department participated in one of the many volunteering opportunities the food bank offers in a program called Fresh Rescue.

Fresh Rescue involves sorting through the thousands of pounds of meats and assorted packaged foods that are donated to the facility by supermarkets to be distributed to food pantries, shelters, soup kitchens, senior centers and more across the state of New Hampshire. It is a huge, organized operation that we are lucky to have been a part of – if only for a short while.

Our Experience

Armed with clean gloves and what to toss flashcards, we dove into the dozens of boxes of frozen meats brought out for us on pallets with a forklift. Spoiled meats, torn packaging and unsealed containers were chucked into a throw-out box, while everything else was categorized and combined into boxes, weighed and stacked for distribution.

In just three hours, our small team was able to sort through 5,464 total pounds of frozen items. We threw away 1,764 pounds, leaving 3,700 pounds of foods to be categorized. That filled 121 distribution boxes, which equaled 3,083 meals to be shipped to people in need!

Volunteering in our communities is highly encouraged at Hoyle, Tanner and we were happy to give back! Special thanks to Nicole Dutka and the Fresh Rescue team for coordinating and making it a memorable experience for our group.

Celebrating St. Patrick’s Day with a Focus on Green (Infrastructure)

Stormwater Detention Pond Construction

To celebrate St. Patrick’s Day this year, we wanted to highlight some the ways we embrace green infrastructure. Sometimes our projects are naturally geared towards sustainability out of necessity (i.e. so we don’t disturb wildlife or certain plant species), while other projects may not have a need for sustainability but we see a way to incorporate it (i.e. better stormwater management).

Before we get into some of the specific green infrastructure examples, it is important to establish some background. First, green infrastructure is not just a marketing term; it is defined by the US Environmental Protection Agency (EPA) as “the range of measures that use plant or soil systems, permeable pavement or other permeable surfaces or substrates, stormwater harvest and reuse, or landscaping to store, infiltrate, or evapotranspirate stormwater and reduce flows to sewer systems or to surface waters.”

In other words, green infrastructure is using natural means to move water rather than building more infrastructure like pipes or drains. These projects are highlights of our recent green stormwater infrastructure.

Green Methodology

As part of a consultant team, we have developed a methodology for the Vermont Department of Environmental Conservation (VTDEC) to prepare cost estimates for the implementation, and operation and maintenance of stormwater projects for all land use sectors (agricultural, wetlands, river/streams, lakeshore, forest roads/trails, roads, urban, etc.), as well as developed an O&M standards manual for continued operation of these practices. The final product was recently submitted to the State of Vermont and will outline how stormwater projects are planned, implemented and maintained throughout the State.

Green Bioretention


One project I worked on was to conduct an Engineering Feasibility Analysis for the City of South Burlington Municipal Office complex which had been identified as a location to evaluate and implement stormwater management improvements. The analysis resulted in the implementation of Low Impact Development (LID) measures. The designed stormwater management improvements included a bioretention facility, vegetated swale, and underground storage system.

The bioretention facility works to collect and absorb runoff from rooftops, sidewalks, and paved surfaces.  Bioretention practices mimic natural hydrology by infiltrating and evaporating and transpiring stormwater runoff.

Green Gravel Wetlands

This project addressed collected stormwater flowing into Bartlett Brook, crossing beneath Route 7 and ultimately into Shelburne Bay in Vermont. The design concept that had been developed by others through the Bartlett Brook Flow Restoration Plan process included capturing collected stormwater runoff from the neighborhood and conveying this stormwater to a City-owned parcel on the west and downgradient side of the neighborhood to allow for underground infiltration. Upon further investigation, site soil conditions were found to be unfavorable for stormwater infiltration. As a result, the Hoyle, Tanner Team designed a gravel wetland at the City-owned site to provide for flow detention and phosphorus removal of the collected stormwater runoff from the contributing residential drainage area.

Green Plans

Finally, but not least in importance, is planning for green infrastructure’s future. As part of a large integrated water quality planning effort for the City of Burlington, green stormwater infrastructure (GSI) projects were included as an important means to reduce stormwater flows and phosphorus loading to the combined sewer system in Burlington.

As part of meeting requirements for different Clean Water Act programs, Burlington’s Integrated Plan is intended to identify and prioritize water quality opportunities that result in a cost-effective program to achieve water quality goals. Tasks included the development of a comprehensive clean water alternatives analysis, including identification of enhanced phosphorus optimization at wastewater treatment facilities; identification of City-wide runoff (stormwater and wet-weather) opportunities; planning concepts for high-priority runoff mitigation projects; financial capability analysis; facilitation of public outreach; and development of an Integrated Plan with an implementation schedule. Burlington’s Integrated Plan development is currently in progress with an anticipated submission to State regulators later this year.

Stormwater runoff is a major cause of water pollution in urban areas, carrying trash, bacteria, phosphorus, and other pollutants from the urban landscape into our waterways.  Implementation of green infrastructure can help mitigate stormwater runoff by providing natural areas within the urban landscape that provide habitat, flood protection, and cleaner water. At Hoyle, Tanner, we look for ways to incorporate green infrastructure into our planning and design concepts to maximize the environmental benefits they can provide.

Part 2: Six Programs that Contribute to a 2D Hydraulic Model & Why They Matter

Hydraulic modeling software image with arrows and blue green and orange colors showing water movement

We introduced 2D hydraulic modeling and its purpose in Part I as a way to calculate how water moves and why we use the modeling to help us engineer better bridges. With that understanding, we can further explain the different ways we get the data to make those 2D models work.

The math and programming are not simple, so using simplified terms, we will break down six common programs and types of data to show how it all comes together.

#1: Google Earth

Google Earth: Many people know Google Earth as a fun tool to see their house or maybe where they want to vacation either in an aerial or street view. Engineers use Google Earth not only to see existing conditions, but also to see the aerial history of a location, as Google has images of the land as it has changed over time. For example, we can use Google Earth to look at a river 20 years ago and see how that same location has changed over that period! Is it wider because the banks are eroding? Has it meandered, causing our bridge to need re-alignment to better fit the path it has taken? Has it taken a shortcut and cutoff any oxbows (or U-shaped bends in the river) over time?

Google Earth graphic showing how the land can change over time. This image shows oxbows cut off over time (change of 22 years shown from 1996 to 2018).

The aerial images also provide information as to the roughness (think texture) or the topography. When the river floods, will the water pass quickly over the smooth fields, or will it slow down because it has to travel through a dense forest with brush scattered over the forest floor? We apply a Manning’s roughness coefficient, n, to this area in the water modeling software to help it figure out where the water wants to move. The street view can help show what the surrounding area is like from the ground to give a better idea of what the roughness should be. Sometimes it is challenging to determine how dense a forest is from the aerial view, but the street view could show if the forest floor is clean with few branches at water level, or if there’s a lot of low branches and additional brush that will slow the water down in the event of a flood.

#2: StreamStats

StreamStats: StreamStats is a web-based geographic information system (GIS) application for water-resources planning that we use to delineate watersheds and determine flow (or how much water is passing through a section). This application uses gage data of existing streams and known flows with regression equations to determine the flood flows at a location without a gage. Now first off, you might be asking yourself “what the heck is a gage?” A streamgage uses instruments to measure and record how much water is flowing in a stream at a particular location. You can learn more about it on the US Geological Survey (USGS) website. Secondly, you might be thinking “what is a regression equation?” This is a type of equation used in statistics to determine a parameter (e.g. flow) based on the relationship between sets of data like watershed size and storage. Essentially, the equations use the information from streams with gages to extrapolate what the flow most likely is at an ungaged site. You can click on a stream point (as long as it’s inside applicable limits) and the program will then delineate the watershed and tell you what your flow is! But as is true with most software, you need to check what it gives you to make sure the delineated watershed is accurate, and the flows are reasonable.

#3: Mathcad

Mathcad: We use Mathcad to perform calculations. For example, New Hampshire requires engineers to complete hydrology calculations for bridge designs; alternative methods to determine the flood flows at the bridge are done to check that the flows determined by StreamStats are reasonable. Again, it’s not as straightforward as “StreamStats is giving me this data, let’s use it,” it needs to be checked! Mathcad allows us to efficiently check the flows from StreamStats by using other methods (i.e. equations). Mathcad is also commonly used to calculate the scour depths around the bridge foundations and size the riprap protection mentioned in Part I.

#4: LiDAR

LiDAR: We also use LiDAR data. While not a specific program, LiDAR gives us images from ground penetrating radar so that we can bring these images into a hydraulic model to merge with survey data. From this information, we can get a fairly accurate account of land to model. LiDAR will reflect things like a knoll in a plane underwater, but it won’t show the water itself; it will show why the water is moving around something we can’t see without this data.

#5: SMS

Surface-water Modeling Solution: More commonly known as SMS, this program is the graphical user interface developed by Aquaveo; this is the software that we use to put together all of the data to create a model that can showcase contours and streamlines representing water. We use the aerial image from Google Earth in the program to define the various areas of terrain roughness; use the flows from StreamStats to tell the program how much water it needs to include; and use the LiDAR to define the topography throughout the model. SMS is especially useful when we are explaining to clients the need for different types of infrastructure or to show the public what’s going on with the water, but it’s also useful for the engineers to be able to see the reason we would need different foundations for a bridge or different materials to construct with because of water flow. For example, although the bridge may span the bankfull width, is the bridge still a constriction in the overall floodplain that could cause deep scour? Or is there an area of the roadway that is still overtopping and might experience erosion?

#6: SRH-2D

Sedimentation and River Hydraulics – Two-Dimensional model: This program is known as SRH-2D and was developed at the US Bureau of Reclamation in collaboration with the Federal Highway Administration and the Water Resources Agency in Taiwan. This is the software that deals with the computational efforts that go on behind the scenes after the model is built in SMS. It’s a 2D hydraulic, sediment, temperature and vegetation model for river systems. SMS and SRH-2D usually confuse people because they think they are the same, but you use each of them for different purposes: SMS is for setup and reviewing results, and SRH-2D is for processing for the information.

There are some programs we haven’t talked about here. For simple culverts, the HY-8 Culvert Analysis Program developed by the Federal Highway Administration may be used. SRH-2D can utilize HY-8 to incorporate culverts within the 2D model; this development of SRH-2D was in cooperation with Aquaveo and the Environmental Modeling Research Laboratory at Brigham Young University. For 1D hydraulic modeling we would use the Hydrologic Engineering Center’s River Analysis System (HEC-RAS) developed by the US Army Corps of Engineers – which can be used for 2D but is not as widely used as SMS, especially in the Northeast. We could also use 3D hydraulic modeling technology, such as FLOW-3D, but that will be more prevalent in the future when computational power can better handle the programs required for it.

Computers have come a long way in being able to process the complicated software to create 2D hydraulic models. While 1D hydraulic modeling gave us more capabilities with bridge hydraulics than just calculators, we are pleased with the extra capabilities 2D hydraulic modeling has afforded us and are always looking for ways to use it better. Want to find out more about 2D hydraulic modeling?

Employee Spotlight: Chris Singer

Chris Singer Airport Engineer and Horticulture Enthusiast

1.  What drew you to Hoyle, Tanner?
The network of offices throughout New England and the luck that there was a branch right next to my school, the University of Central Florida.
2. What’s something invaluable you’ve learned here?
My CAD skills have drastically improved over those that I developed in college.
3. What’s your favorite time of year to work at Hoyle, Tanner?
The summer because the majority of the projects start construction.
4. What’s the coolest thing you are working on?
I just started as an engineer in January so I have not designed much yet, but I am excited to work out in the field this spring and summer.
5. What’s the best thing that’s happened to you so far this week?
One of the pineapples that I’m growing has started to sprout, so only another couple of months to wait.
6. How many different states have you lived in?
Just two, Florida and New Hampshire.
7. If you could only eat one meal for the rest of your life what would it be?
I would choose apple cinnamon waffles (with real maple syrup), home fries, and both brisket and pork breakfast tacos.
8. What kind of pet do you have and how did you choose to name it?
I have two dogs; a 6-year-old pitbull mix named Burton after the snowboard company.  I just got a standard poodle puppy named Oliver, and that name just sounded good with Burton.
9. What is a fun or interesting fact about your hometown?
Concord has a smaller population than the University of Central Florida, where I just graduated from.  
10. What are three things still left on your bucket list
1. Thru-hike the Appalachian Trail
2. Go Skiing in the Alps
3. Own a farm or an orchard

11. Name three items you’d take with you to a desert island.
I’m probably overthinking this but,
1. A solar desalination unit (which does not exist)
2. A fishing net
3. A dog for company

12. What characteristic do you admire most in others?
Motivation, it is easy to settle into a routine but disrupting it is hard to convince yourself to do.
13. How old is the oldest item in your closet?
My first pair of Birkenstocks that I got 10 or 12 years ago, only the straps are still original.
14. Words to live by? Favorite Quote?
Not really a favorite quote but one that has stuck with me for many years is by Kurt Vonnegut; “We could have saved the Earth but we were too damned cheap”.
15. What did you want to be when you were growing up?
Lots of different things but most of them revolved around animals.
16. If you were to skydive from an airplane what would you think about on the way down?
I have gone skydiving from 16,000 feet and mostly thought about how I was mad that it doesn’t give you that feeling of your stomach rising in your chest like really fast rollercoasters do. I could also see the NASA Vehicle Assembly Building (VAB) because I went skydiving in Titusville, FL.