Potential bridge sites in the Tophet Swamp

The "Minuteman Connector" part of the proposed West Lexington Greenway (WLG) project will have to cross Kiln Brook, the major stream flowing west from Lexington into the Shawsheen River in Bedford. 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.

Out on the snow and ice after two inches of rain...

I was afraid the nearly two inches of rain Friday would wipe out the ice for the winter. Worse, temperatures over 50 F. were forecast for Saturday. However, the overnight freezing fog raised my hopes, and I made an early start Saturday morning while the temperature was still below freezing. Black ice covered many streets, but where the rising sun struck dark frosty surfaces, billows of vapor showed the freezing temperatures would be fleeting. Meanwhile, I was glad to have the studded snow tires. Even the cars were slipping on the black ice.

The Minuteman bike trail just west of the Bedford Street crossing was still covered with snow, and I was delighted to see a lot of apparently solid ice, where the slushy mixture had frozen overnight. My glee turned to disgust as I broke through the top half-inch of ice and wallowed in several inches of liquid slush. Was this another wasted day for riding?

Luckily the slushpot was not too extensive. It only covered about 100 feet of the paved bike trail, but I decided to get to a wooded area as quickly as possible. Without pavement underneath, the water has a better chance to drain into the soil. With the school bus parking lot on my right, I cut left on the little trail across the playground, managed a couple of circles on top of the snow without breaking through the crust, then continued onto Garfield Street and the entrance to the Meagherville conservation land at the playground at the end of Garfield. The baseball field looked like a skating rink, the kind of area that makes ice biking so much fun. But again I was to find only disappointment as the thin ice over slush betrayed me, and I found myself pushing the bike through several inches of the gloppy stuff. The main trail into the woods in Meagherville was more favorable for riding, and I had an enjoyable ride on the white blazed trail, and the yellow blazed connecting trail back to Ward St. The ground fog was quite nice in the early sunlight, and I made a decent snapshot of one very nice ice stretch which really represents the opportunities for ice biking on the wooded trails.

I have high hopes for the prospects for great ice biking in the coming week. The temperatures are predicted to remain below freezing for nearly three days, with lows below 10 F. This will allow the slushy trails to really freeze solidly. It will be dangerous for anyone on foot without crampons, but it's shaping up to offer a few days of some of the best ice biking in recent years. It's too late for safe riding on the bodies of water, I think... That ice has been corrupted by the rain and warmth, and will not become safe again with only a couple of days of freezing. But the icy trails should be glorious, if I can get a few hours free to enjoy them....

After making my way back to the Minuteman Bikeway's railway bridge to cross 128 on the way towards Bedford, I turned left at the end of the wooden guardrail, onto the Tophet Swamp/Katahdin Woods trail. Although the softening snow crust made for slow riding and frequent walking, I took a few images of one of the larger fallen trees which block the trail. The arrow-straight trail in this section is no accident: It lies atop the sewer line, whose levee-like bed provides the only dry ground between Rt. 128 and the towering edge of the town's landfill/composting facility.

I also scouted out a potential crossing spot for the Minuteman Connector, for the location of a bridge across one branch of Kiln Brook. More on that tomorrow. It's late, and that's all for now... .