On Saturday, March 3, I checked out one potential site for a bridge crossing one of the tributaries of Kiln Brook. This is the bridge labeled "1" on the Google Earth-derived projection here. Clicking on this photomap should allow an enlarged view.This photomap of the project area in the Tophet Swamp conservation land may help in visualizing the challenges of siting a sustainable heavy-duty trail in this area. Two major branches of Kiln Brook flow from the bottom of the image, under Rt. 128/I-95, then join and flow to the right, toward the composting facility, and thence under Hartwell Avenue at the top of the image. These branches are mentioned as the northern (right) and southern (left) branches, in the discussion below. The gray-green areas along the streams are mostly wetlands or open water. Uplands where a trail could find a base of dry land show up as lighter gray in this image. Pines groves, with their green needles visible in some areas, also mark relatively dry uplands.
The photomap also shows where the current trail (in red) encroaches on the I-95 right-of-way. With no existing bridges across Kiln Brook, the current trail is forced onto the highway land in order to cross over several of the culverts which carry Kiln Brook under I-95. Even if the heavy-duty stone-dust version of the Minuteman Connector concept is proved infeasible, the town of Lexington still should install foot bridges to allow safe travel in this conservation land without the need to encroach on the highway right-of-way.
The area around bridge site "1" in the photomap was investigated a few weeks earlier by the WLG team. The current snow cover makes it easier now to pick out the traces of older trails through this low-lying landscape. With the leaves gone and the snow background making the trees stand out against the ground, the older trails are often easier to spot. I made a couple of photos to illustrate this opportunity to resurrect the older trail system as part of the basic framework for the proposed WLG trail system in this area. These photos show details of the bridge site labeled "1."
First is a view of the "peninsula" where the buried sewer line passes under a branch of Kiln Brook. (The current trail from the Minuteman Bikeway, marked in red in the photomap, runs straight as an arrow upon this sewer line, until it suddenly swerves left toward Rt. 128 and crosses a culvert just before this point.) The northern branch of Kiln Brook flows from the left around the end of the peninsula. The tributary from the right joins it, and they both flow away toward the upper right, not easily visible in this photo. The potential bridge site is on the right side of this photo, crossing the tributary. In this photo it appears as it was before I made a few tracks in the snow as a highlight.
The second photo is a view with tire tracks headed across the Kiln Brook tributary which drains the large area of open water between the trail and the composting facility. This photo clearly shows the opening between the trees on the other side, where the older trail had crossed that tributary in earlier days. The activities of beavers in the Kiln Brook/Tophet Swamp basin have apparently affected the water level of this tributary so that it is now nearly always too deep to cross casually.
However, I remember crossing here with little difficulty when I first began to explore this area, nearly ten years ago. Fallen branches on the other side have also contributed to the obliteration of the older trail.The land visible across the tributary is essentially an island when water levels are high. If the Minuteman Connector trail follows this route, it will still need to cross the main channel of Kiln Brook in order to continue south. One possibility might be to choose a path which will only cross the main channel, but from this "island," there is a substantial stretch of wetland to cross before arriving at the channel itself. The photomap shows this clearly.
An option which may result in less wetland crossing is shown photomap, based on using two bridges to cross first the northern branch, then the southern branch of Kiln Brook. There appear to be potential bridge sites (labeled 2 and 3) at which a bridge can butt on relatively higher ground on both sides. In this way, most of the trail in this area may be able to avoid wetlands and the need for raised boardwalk construction. Careful surveys will be needed to really evaluate this route, and the WLG team expects to draw on professional expertise obtained through Community Preservation Act funding to help bring this trail concept closer to reality.
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