Paved Surfaces, Salt and Water Bodies: A Bad Mix

This news item from the February 17 Republican underscores why it’s a bad idea to locate paved surfaces near bodies of water…

Road salt taints 9 home wells

Tests of private home wells along Route 10 have shown that three in Westfield and six in Southampton are contaminated by road salt, officials said yesterday…

All of the homes that have salt contamination in their wells are on Route 10, which is treated with road salt by the state Highway Department, said Anne M. Capra, a principal planner with the [Pioneer Valley Planning Commission]…
Let’s recall that Kohl Construction’s proposed condo development off North Street calls for paved surfaces as close as 35 feet or less from the wetlands surrounding Millyard Brook.

As this report from Hyla Ecological Services explains, wetlands buffers of less than 50 feet are simply inadequate protection:

…The following summary findings, excerpted from Castelle et al., 1992 are particularly germane to this discussion:

…Buffers of less than 50 feet in width are generally ineffective in protecting wetlands. Buffers larger than 50 feet are necessary to protect wetlands from an influx of sediment and nutrients, to protect wetlands from direct human disturbance, to protect sensitive wildlife species from adverse impacts, and to protect wetlands from the adverse effects of changes in quantity of water entering the wetland. (p. 44)

Buffer function was found to be directly related to the width of the buffer. Ninety-five percent of buffers smaller than 50 feet suffered a direct human impact within the buffer, while only 35% of buffers wider than 50 feet suffered direct human impact. Human impacts to the buffer zone resulted in increased impact on the wetland by noise, physical disturbance of foraging and nesting areas, and dumping refuse and yard waste. Overall, large buffers reduced the degree of changes in water quality, sediment load, and the quantity of water entering the adjacent wetland. As a rule, buffers were subjected to a reduction in size over time. Of 21 sites examined, 18 were found to have reduced buffer zones within one to eight years following establishment. (P. iv, bold-type added).

Even if the condo development goes on a “no-salt” diet and treats its paved surfaces only with sand, this will increase the risk that the detention ponds, the wetlands and Millyard Brook will suffer from silt build-up.

See also:

Gazette: “Salt suspected in Southampton well contamination” (2/19/08)
Some homes with wells on Route 10 have 14 times more salt, or 280 milligrams of salt per liter, in their drinking water than the 20 milligrams per liter recommended by the Environmental Protection Agency, according to town officials.

That is “a little off the chart,” in the words of Mark Girard, chairman of the Planning Board and member of the Barnes Aquifer Protection Advisory Council…

Timothy and Linda Wing, both 62, of 407 College Highway, started drinking bottled water about a year ago, when a group from Smith College tested the water and advised them not to drink it…

According to the U.S. Environmental Protection Agency’s Web site, salt is a cheap and effective solution to ice-covered roads that can be a problem for drinking water systems as runoff affects local soil quality, groundwater and surface water supplies…

Alex Ghiselin, Letter to Gazette: “Don’t let development encroach on our wetlands”
Northampton has a natural wetland system that protects us from flooding, nurtures biodiversity and filters our groundwater. Allowing development within 10 feet of this system in almost every residential district is not a good idea.

The failure of the storm water system built as a part of the Northampton High School renovation six years ago illustrates why protecting wetlands is so important. Silt has filled the retention pond so there is no capacity to slow a storm surge which now flows unimpeded into the Mill River and contributes to flooding downstream. This accumulated silt also raised the water table and spills ground water into nearby basements…

Without maintenance, these [storm water mitigation] systems are part of the problem, not the solution…

Wetlands do not need to be maintained; they just need to be protected.

Mike Kirby: Compensatory Wetland on Carlon Drive Not Working
Detention ponds have to operate independently of rising groundwater levels: they have to have to hold runoff from big storms for some time period, and then discharge it when the peak runoff time has passed. They have to be above the flood plain.

In Carlon Drive, they simply scooped out a hole in the swamp-bottom, and called it a detention structure. Today it is just a pond, and a stagnant smelly one. It was designed to have a dry forebay, and a shallow main chamber was supposed to have only about 6 inches of water in it. This was supposed to be a compensatory wetland, full of cattails and wildflowers. A rock check dam was supposed to hold back the “first flush” off the parking lots and trap pollutants, and outflow from it was supposed to feed the wet part of the detention pond. Here rain water pouring off the new parking areas and street was supposed to be stored, and discharged safely.

That was the plan. Today if you stand by the pond and look down into it, you’ll see the check dam is now about two feet underwater. You can’t even see where they planted the marshgrass and flowers. The area is under water. Even in a fairly dry summer, the detention pond is only about a foot and a half from the top of the bank. There’s no storage to speak of, no discharge, no filtering. As it is constructed now, grey water from the parking lots and the access street goes directly into the swamp and the Connecticut River.

Connecticut River Watershed Action Plan: Remove impervious surfaces within 50 feet of streams
To reduce nonpoint source pollution from stormwater runoff, the Connecticut River Strategic Plan proposes the removal of impervious surfaces within 50 feet of streams and the investigation of “functional replacements” (such as the use of permeable pavement) for impervious surfaces within 100 feet of streams, in developed areas (PVPC, 2001). In the urbanized areas, the removal or retrofitting of impervious areas and the implementation of Stormwater Best Management Practices (BMPs) could be beneficial in improving water quality.

Photo Essay: Millyard Brook Swells with Water in Winter

Snow and Slush Expose Limits of Storm Drains