Published DateTo the editor,
A recent posting on the Plymouth town website titled "A few facts about the Riverside Landing development" makes scientifically misleading statements about hydrology, the town's drinking water supply, and runoff. For example, "Test borings for new wells in that area have found no aquifer." While it's true that the district's well-head protection area around our existing wells does not extend up the Baker River valley to the project site, the aquifer from which we draw your water supply comes from a sand and gravel aquifer upgradient of our well-head protection area, including up the Baker River Valley. Our wellhead protection area is a legally defined small area immediately surrounding our wells, and NHDES recognizes that it is a compromise between development and water supply protection. The inadequacy of the designated wellhead protection area is why so many wells in N.H. (including ours) have high levels of chloride from road salt (as one example). A further statement that "the increase in the salt in (district) drinking water — (is) up to 120 ppm since 1977" is inaccurate — the level has increased from just 6 ppm (parts per million) in the 1950s to over 190 ppm recently, closing in on the EPA drinking water limit of 250 ppm because of impervious development upgradient of our wells.
Contrary to the town website, no test borings for new wells have been drilled in the area of Riverside Landing but we know from reports from the U.S. Geological Survey that this area feeds the regional aquifer that includes the town water supply. The town's statement "no untreated runoff will leave the subject property" does not acknowledge the fact that chloride is highly soluble and very mobile and cannot be "treated" — it will indeed enter the groundwater or will runoff to surface water. Because of the proximity to the river, other contaminants will flow off the impervious surfaces of this and other developments and will not be treated.
To say that "captured runoff would be cleaner than rainwater by the time it made its way back into the environment" is wishful thinking. See NHDES Fact Sheet WD-DWGB 22-4 "Best Management Practices (BMPs) for Groundwater Protection" dated 2009 which cites "stormwater infiltration ponds or leaching catch basins" as "potential contamination sources". The district would like to think that low impact development (LID) approaches be required by the Plymouth Planning Board to mitigate stormwater concerns, but will they (see NHDES Fact Sheet WD-WMB-17 "Low Impact Development and Stormwater Management")? The state encourages low impact stormwater management such as porous pavement which was used at the Pemi Commons development recently on Fairgrounds Road. This pavement is not impervious and so very little salt and no sand needs to be used because water doesn't stand on the surface. Will LID measures be required of the Riverside Landing shopping center as proposed, or will the "most studied piece of property in the Town of Plymouth" be exempt since it's modeled after a five year old development as proposed by Lowes?
Finally, we should all be careful of accepting 'studies' about what the town website calls the most "studied" piece of property in the town of Plymouth. One expert enlisted by the Lowe's developers claimed that there was no evidence that the Baker River had ever changed it's course in this area, yet there are former river channel oxbows on all four sides of the property. An expert will provide any answer for the right price.
We should all be focusing on what's best for Plymouth's environment since that is where we live and draw our drinking water from! Let's use the most modern methods of development for all future development in Plymouth.
Dick Flanders, Chair
Plymouth Village Water & Sewer District