Groton Open Space Association

From Baker Cove To The Ledges: A Walk Along A Stream Under Pressure

GROTON–The following is the text of a presentation to the Zoning Commission during a hearing on stormwater management and allied topics by Joan Smith, GOSA president. Date of presentation was Jan. 5, 2011.

Bacterial contamination has been documented in Baker Cove. Ed Martin, Chairman of the Shellfish Commission, provided evidence that impacts to estuaries are greatest where the percentage of impervious surface within a watershed exceeds 25%. He provided maps documenting that Baker Cove and other watersheds in Groton already exceed that critical 25% threshold, and he correlated existing impacts with those higher percentages.

It is unfortunate that staff has publicly discredited the expertise and authority of  Mr. Martin as well as that of GOSA consultant Steve Trinkaus and Dave Kozak of the CT DEP/Long Island Sound Program, and it is disappointing to see staff argue that protection of our estuaries and drinking water is neither related to stormwater regulation, nor lies within the jurisdiction of the Zoning Commission.

The Eastern Connecticut Conservation District has been tasked to identify the causes of the bacterial contamination of Baker Cove, and has begun conducting a visual inspection of the watershed.  I accompanied the group on some of their inspection tours: by kayak in Baker Cove and on foot along several streams, including Birch Plain Creek.

 The following description will illustrate how stormwater runoff, contiguous impervious surfaces and dense development can have a predictable and negative impact on water quality.

 For this particular day, our mission was to walk upstream, beginning in Baker Cove, to conduct a visual inspection of an unnamed stream that enters the cove at a right angle to Birch Plain Creek, travels parallel to Thomas Road, and follows the Providence and Worcester Railroad. The stream appears on both sides of the tracks, then divides in two, with one branch wrapping around a mobile home park, and the other, which we followed, continuing straight toward Amtrak and the Big Y shopping center.

The straight branch passes under the Amtrak berm through a culvert, and emerges to daylight on the other side, next to Planet Fitness, a part of the Big Y center. The stream remains above ground for about a hundred feet before it completely disappears beneath the parking lot. We followed its progress diagonally across the Big Y parking lot. One branch of the stream emerges at the Avery Family memorial park, while another appears to go under Route 1, traverse a diagonal under the entire Benny’s/Post Office parking lot, and emerge in a naturally vegetated area next to the Post Office.

 We followed this branch toward Drozdyk Drive, and beyond as it continues along a steep hill past the Ledges apartments. We observed the stream going under I-95, and noted on a map that it ends not far north of the highway in a wooded area.

Our field notes include a summary page describing the general characteristics of the stream, and we identified waypoints using GPS technology. Photos were taken to illustrate points of interest, and good conditions are described on Page 1. Impacts such as trash, sediments, erosion, leak-offs, pipe outfalls and buffers of less than 35 feet are described in detail on separate pages. Lawns, pavement and lack of shade at the edge of streams and wetlands were documented as negative impacts.

So, too, were pet wastes, automotive spills and bird droppings that could wash off from the pavement into the stream and associated wetlands.

We peered into catch basins, and documented pipe outfalls and any development close to the stream, including back yards, roads, drainage trenches, culverts, parking lots, and businesses and residences in the Thomas Road neighborhood. Turtles had nested in the gravel berm of the railroad tracks.

Further upstream, we passed a densely developed mobile home park that features buildings, lawns and roads constructed right up to the edge of the stream. The dead end roads emptied straight into the stream by asphalt and concrete leak-offs, and sediments and bank erosion were evident, as were flooding impacts such as scouring.

 Roads are considered a source of contamination from automobile chemicals, pet wastes, road sands and deicing chemicals. Lawns are considered a source of contamination from fertilizers, herbicides and other landscaping chemicals, and lawns do not provide the high-quality detention, filtration and water recharge functions of a naturally vegetated buffer.

Beyond the mobile home park, the stream separates, with one part turning away from the main branch to wrap closely around another side of the park. We chose to go straight, following the main branch towards its intersection with Amtrak. As we approached Amtrak, we saw a lot of trash and many shopping carts within the stream on our left side. To our right, conditions were better. A large potential vernal pool and wooded wetland were protected within the contours of a railroad Y, an area between three sets of tracks. 

As the stream passes through a culvert under Amtrak, and emerges above ground for about 100 feet, we observed more trash and more shopping carts. We also saw feral cat shelters and feeding stations on the stream bank, and a large compost pile containing landscaping materials, such as leaves and tall grass cuttings. We saw multiple bird droppings on pavement close to the stream. This part of the stream is located close to the Planet Fitness corner of the Big Y shopping center.

A star-shaped cluster of culverts and pipes emerges from beneath the parking lot and empties directly into the stream. The pipes appear to come from several directions and there is no apparent treatment for removing sediments, dissolved pollutants and suspended solids from the water. The pipes are built into a concrete structure that supports the parking lot, and this structure is fenced off.  One of these pipes contains the flowing stream that we have been following.

By peering into the grates that capture stormwater from several low points across the parking lot, we could see a brisk water flow and determine the direction of the stream. Under the first grate, we could see a pipe that drains stormwater from the roof corner at Planet Fitness directly into the stream. There were no apparent signs of pretreatment to remove pollutants from the roof runoff. The stream flowed briskly, as seen through more grates, indicating a diagonal direction across the entire Big Y parking lot, until one branch emerged to daylight at the Avery Family memorial park.

To be fair, new construction at CVS and Starbucks may have some pre-treatment systems at the periphery of the lot, but the stream itself appeared to collect a lot of untreated water from the open grates in the center of the lot. Landscaping islands did not contribute to absorption or infiltration of stormwater runoff, since they were surrounded by elevated curbing.

A second branch of the stream crosses Route 1 and traverses a break in the front row of the commercial buildings facing the north side of the street. The stream then travels diagonally under the Benny’s/Post Office parking lot, until it emerges once more into a natural area next to the Post Office. Open grates capture stormwater from what appeared to be the entire parking lot. Drains along heavily traveled Long Hill and Poquonnock Roads appeared to flow directly into this system as well. The Conservation District will include relevant maps of the system in its report.

Continuing upstream, there is a more natural buffered area as the streambed passes under Drozdyk Drive and then continues on the hill next to the Ledges apartment complex. Level spreaders and native species plantings appear to mitigate some development impact from the Ledges, despite its large impervious surface area. The stream continues through a surprisingly dramatic and scenic ravine next to the Ledges, then enters a culvert under Interstate 95, before ending in a wooded area north of the highway.

Stormwater impacts and nonpoint source pollution as illustrated here are a very real problem in Groton’s urbanized areas. Birch Plain Creek has similar impacts from roads, road sand, blocked catch basins, parking lots, a rusted-out sanitary sewer structure, lawns, ball fields, golf courses, landfill, compost heaps, landscaping stockpiles, buildings and underground culverts. Some of our waterways are no longer safe for swimming, shellfishing or other recreation because of extensive urban development, large contiguous areas of impervious surfaces and untreated stormwater runoff. The future quality of our watercourses, Long Island Sound and our drinking water depend on your decision tonight.

Despite advice from staff to the contrary, you do have the authority and jurisdiction to adopt strong and protective stormwater regulations. You can do so without having to sacrifice future quality development. Please do not approve the regulation amendment as proposed. It is too narrow in scope and skips the essential stages of planning and evaluating how the entire set of zoning regulations fit together. Avoid the present fragmentation of the rewriting process. Insist on more complete information, and create a more comprehensive and protective body of language. Take advantage of the expertise offered by the State DEP, study sample regulations from other towns and take the time you need to do this right.