This is part six of nine in the Paving Paradise series. To read the full article click here.

Perryman Wellfield Protection District

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In addition to industrial use limitations, the Harford County zoning statute 267-77 Wellfield Protection District limits impervious surface creation to a maximum of 50% for any new development within the Perryman Wellfield Protection District. Despite this regulation, analysis using the NLCD shows that impervious surfaces within the district have increased 11% between 2001 and 2019, totaling an estimated 49.46% of land area. The protection district also covers a section of APG that has seen little to no impervious surface increase over the last 20 years. Looking only at Harford County land within the district (roughly a third), impervious surfaces have increased 23% over the 19-year analysis period to a shocking 62% of total land cover. This raises the question, how can impervious surfaces increase beyond 50% despite zoning laws capping impervious surfaces to 50%? The answer is multifold.

First, the zoning statute addresses land cover only at a property level and makes no mention of cumulative land cover within the district. Thus, if every property development maintains less than 50% imperviousness, the developments can keep coming, despite continually raising the overall imperviousness of the protection district. Additionally, public infrastructure like roads and utility easements, notoriously impervious land use types, are not included in private property calculations. However, the most significant contributing factor to the disparity between intended and actual impervious surface amounts is the method used by developers to calculate the impervious percentage for a proposed property. Similar to gerrymandering, planners deliberately cut and shape parcels into lots, staying below the 50% rule within each lot. In simple terms, they will draft lots that take pervious surfaces from outside the protection district to balance the impervious surface within the wellfield, disregarding existing hydrological and tax parcel boundaries. In the case of the Mitchell property, two lots intersecting the protection district have a planned total impervious surface coverage exceeding 49.5% — just barely below the 50% limit.

The 711-acre Mitchell property will be 85% impervious once it’s developed, with 108.5 impervious acres falling within the wellfield protection district, only further increasing risk to drinking water. Planning documents for other facilities obtained from MDE using Maryland’s Public Information Act show a similar trend of developers subdividing parcels to meet the 50% rule in Perryman. Although Harford County law aims to protect the wellfield, its zoning regulations render the law virtually ineffective in restricting impervious surfaces due to focusing on individual parcels, not accounting for impervious public infrastructure, and allowing for parcel subdividing. The problems caused by virtually unregulated impervious surface in the wellfield are compounded by the nearby Michaelsville Landfill, a superfund site in APG containing trichloroethylene (TCE).

TCE is a cancer-causing legacy pollutant once used by the military as a flame retardant and currently used as an industrial solvent and refrigerant. TCE is in the chemical family of Per- and Polyfluoroalkyl Substances, commonly known as PFAS, and is responsible for a host of health effects, including kidney and liver cancer and neurological diseases. The federal government declared the Michaelsville Landfill a superfund site in 1989. Heavier than water, TCE filters through soil and can infiltrate groundwater sources, potentially harming well users. According to the EPA, TCE is “the most frequently reported organic contaminant in groundwater” and “between 9 and 34 percent” of drinking water supply sources have some TCE. In February 1992, TCE was detected at two of the nine Perryman wells. Carbon filters were installed in 1993 and 2003 to safeguard against contamination and bring concentrations below detectable levels. Current data shows that TCE concentrations average 1.8 ppt (parts per trillion) at the contaminated Perryman wells, below the EPA limit of 70 ppt for PFOS (a subset of PFAS and TCE’s regulatory category). Despite mitigation measures, the threat of contamination persists. TCE was recently detected in community wells in 2005 around Havre de Grace, a city just north of the Perryman. TCE vapors were detected at the Michaelsville landfill during the most recent follow up study in 2018.

Poorly handled runoff from distribution centers could further enhance risk. As noted above, the health risks of PM2.5, brake dust, and a myriad other air and water pollutants increase dramatically with intense truck traffic and impervious surfaces. If impervious surface runoff is not properly infiltrated or allowed to percolate naturally through the ground and replenish the aquifer beneath, “water will fill in from further away from the wells, potentially resulting in contaminated water from [APG] reaching the wells,” according to stormwater expert and resident Stacy Stone. Although distribution centers are required by County law to pretreat and handle runoff in a way that will “minimize ... impact of pollutants to the wellfield,'' stormwater plans for light industrial facilities in Harford County necessitate using only 10-year storm estimates based on the last 30 years. Hurricanes and other storms are increasing in frequency and intensity in the Mid-Atlantic. If planners do not have accurate data to put into their forecasting models, infrastructure aimed at protecting drinking water resources and the environment from contaminated runoff will likely be insufficient. Future mitigation efforts and treatment infrastructure will inevitably be funded by Harford County taxpayers and water users, increasing the social cost from distribution center development.

To see the next section in the Paving Paradise series, Unequal People click here.