 Stream smart road crossings are designed to restore and reconnect aquatic and terrestrial habitat, as well as make sure the infrastructure is resilient to large storm events. To accomplish this, it's important to build stream beds and stream banks within the new crossing and connect them above and below into their natural stream environment. In this video, we're sharing techniques to help you build the stream bed and stream banks appropriately so that wildlife can cross through without going over the road, as well as make sure the new roadstream crossing can handle large storm events in the future. The first step towards designing your stream smart crossing is surveying the stream above and below the roadstream crossing. In this survey, you'll determine the elevations that your topography is set at to make sure the new roadstream crossing is set at the right elevation. In the survey, you'll also determine what the potential scour depth is of the stream naturally to make sure, again, the roadstream crossing is designed and set appropriately. In the survey, you'll also measure the bankfull width, and this is important because it will determine the size of the crossing. Stream smart crossings are 1.2 times the natural stream bankfull width. That's about 20% larger, and this ensures that the crossing is large enough to withstand those larger storms and have enough room to pass logs or other debris that wash through, as well as make sure there's enough room in the new roadstream crossing to build stream beds and stream banks. In the survey, you'll also analyze the substrate that naturally occurs within the stream. You'll determine what size material is immovable and what size material is moving through dynamically. Having this data to determine the size material is crucial to make sure the material you're putting into the new roadstream crossing is stable. You want large immovable materials as foundations for the stream banks, as well as dynamic stream bed material coming in and moving out in the same way it would in the natural section of the stream. In implementing your roadstream crossing project, the stream bed and banks need to tie in up and downstream to make sure the aquatic and terrestrial habitat is connected. This essentially makes sure that the wildlife can move through as if the road is completely invisible to them. When we're building stream banks inside a new stream smart crossing, like this one, we start at the bottom, well below what you can see here at the bottom of the footings, the bottom of the abutments, and we layer, rock and find material in to the point where we are finished with a relatively smooth top layer, but what you don't see here is that there is an immense amount of large stable rock that is not going to be moving even in large storm events. We accomplish this by doing that layering starting at the bottom with large rock off an angular rock, not like you see here, that helps to lock together and we fill it, we layer it with fine material that helps to fill the voids among the larger rocks and that also helps to lock that matrix of rock together. We don't want these stream banks to be moving over a long period of time. We build those banks upward in layers, sometimes three layers of large rock interlayered with three layers of fine material finishing on the top with relatively smooth banks with a lot of fine material on them with a width of say 12 inches or more for a smaller crossing up to maybe three feet for a larger crossing. When we're building stream smart crossings and we build the stream banks inside those crossings it's really important for us to provide access for terrestrial creatures to be able to get to their habitat or to pass through their habitat that we're creating here in our crossing. We want to be sure that all four corners of our banks connect to the natural stream banks. So it's really important that we take a look at these banks and notice that up above them is a slope of riprap very steep rock. We want to make sure that when contractors are placing that rock which is very important that it not simply spill down and cover our otherwise relatively smooth stream banks that we've created. It's this sort of surface that is really helpful to allow all sorts of small mammals to get passage through our crossing and on into the rest of their natural habitat. Within days of our opening crossing sites we have encountered fox, raccoons, mink and other critters inside of our crossings using those banks so we know that they actually work. The stream banks that we build in a stream smart crossing are really important. They have three particular functions that we really think are vital for you to think about. First of all they provide armoring for the abutments and the footings of our stream smart crossing. This is really key to protecting those features that help keep the whole structure stable over a really long time. The second most important thing about building stream banks in a crossing is that we give the stream and the crossing the correct dimensions and form of the natural stream. We are trying to mimic the natural stream upstream and downstream in shape and dimensions and so that's what these stream banks help to give us providing especially also a low flow channel so that our low summertime flows are concentrated somewhere in the middle of the stream providing greater depth for fish to pass through during the summertime. The third item that's really important about stream banks I've already mentioned and that is for the passage of terrestrial creatures along these stream banks otherwise they would have to go up and over the road and face the threat of traffic. Building the stream bed inside of our new stream smart crossing is quite different than building the stream banks. We had previously done a survey to know what the distribution and size of the sediment is inside the stream bed and when we're building an open bottom crossing we want to leave as much of the stream bed here as possible primarily digging trenches on each side for our footings and abutments and to disturb the stream bed that has naturally been here for a long time as little as possible. We can dig our trenches we can install our footings we can then build our stream banks but when it comes to the stream bed we want to disturb as little as possible but we know that we'll end up having to put some of that material the correct size material back into all the spaces that we've needed to excavate and so we need to make sure that we have the right size and distribution and that we match the correct form of the stream. Things are quite different when we're building closed bottom structures if you build a concrete box culvert or perhaps a metal pipe culvert that has a bottom to it we embed those down into the stream bottom and that means when we do our excavation we have to excavate the entire area of the crossing and so that means we need to rebuild our stream bed entirely from the bottom up and so we use that correct mix of sediment sizes from the stream that we have surveyed previously all the mix of fine material and the appropriate size gravel cobble and what have you into the bed of the stream. One of the key elements of our initial survey in preparation for designing a stream smart crossing is to understand to know what the stream substrate distribution is the size and distribution of the pieces of material naturally in the stream so we go away from the disturbance area of the culvert and we measure and count essentially a hundred pieces of what's in the stream in most cases to be able to know what that distribution is so that we can build it into our new stream smart crossing. Using this what we call our gravelometer it gives us the size very easily of these pieces of substrate material to be able to do that kind of counting and assessment really quickly and efficiently. We then take that data and can give it to a contractor to know very well what the distribution and type of material they need to rebuild the stream bed inside our stream smart crossing. There are two really important things we like to try to avoid that we see folks doing a little bit too often. One is when they put in one of these embedded culverts they're worried about scour and so they put in way too much large rock in the bottom of the structure even though the local stream doesn't exist in the same way. Please do not over armor the stream bed inside your crossing. Armor rock is for protecting footings and abutments and creating stable banks not for the stream bed. We want to install embedded crossings below the level of scour so that pools typical of that stream can occur at their natural depths inside the crossing. We want the stream to be able to move and shape itself as it naturally would scouring pools and piling up gravel and other material in other spots within the stream smart crossing. The second thing we'd like to avoid is any kind of compaction, mechanical compaction of material inside an embedded stream smart crossing. That's just not the way the stream acts naturally and it is not necessary if we've designed the stream smart crossing to be at the correct elevation embedded properly you're going to have a dynamic stream bed that is able to move. We don't want just a very shallow long riffle throughout our entire stream smart crossing that's not stream smart. We want the stream to be able to scour pools and then pile up material into shallower areas as it chooses to do. Another feature to consider in your design is drainage ditch outfalls. Drainage period. Often these drainage ditches flow into the stream immediately adjacent to a stream crossing and this is really contrary to current practice to keep sediment out of streams. Be sure to consider this kind of input from drainage ditches when you're designing your stream banks. If you have drainage ditches or drainage pipes flowing near the outlet or the inlet of your stream you want to be sure that the bank areas there are built strongly to be able to withstand the energy of the water coming from those ditches. If possible try to move the ditch input away from where the constructed banks tie into the natural bank as the drainage water can scour away your connections between the constructed banks and the natural stream banks. When we're closing out a stream smart crossing site we want to be thinking about making sure that we revegetate any disturbed areas where we've had excavation equipment with native plant species. In fact before we even begin we should probably be thinking about taking out fewer trees and shrubs than we sometimes do. We need to think about those things because they are much better for the health of the stream keeping the water cooler and less disturbed by sedimentation throughout the construction process and afterwards for the health of the stream and the critters that use it. We want to be sure that open areas that have been disturbed are revegetated naturally and that means trying to find a good seed mix that represents species from the local area as much as possible perhaps replanting native shrub species in the area. Our goal here is absolutely to exclude invasive species that might otherwise come in. Sometimes they're brought in inadvertently on construction equipment. We certainly want to be thinking about that and we want to do what we can to exclude those invasive species and in fact supplant them with native species as much as possible. In stream smart crossings we like to make sure that we're thinking about the disturbance area we create around the crossing so we like to take as few trees out as possible we like to minimize that disturbance area in order to benefit the terrestrial creatures and the aquatic creatures in the stream. We like to minimize the amount of runoff from the adjacent land that can add sediment to the stream and can also add warmer water to the stream and for fish like brook trout and Atlantic salmon they like nice cool waters shaded by native vegetation and so we like to be sure that we're providing that native vegetation but it's also really important for terrestrial critters to be able to have that vegetation to move between and among to be able to hide and protect themselves from predators. In a crossing like this we've got a lot of open area. I wish we had left more trees here and disturbed less of the area. I'm really glad that we have a lot of this plant material here but we don't have shrubs and so animals can't stay where they'd like to be along the stream corridor they need to hide from predators out in the woods and so we need to do a better job at our stream smart crossings planting shrubs and planting native trees it's not that difficult it doesn't take that much more time and it really helps to cool the stream and provide the kind of protection both for the aquatic critters in the stream and those that use the stream corridor. By thoughtfully restoring stream beds and banks in our stream smart crossings we can not only protect our road infrastructure from large storm events but also maintain well connected habitats not just for fish but for semi-aquatic and terrestrial species as well.