Glossary — Environmental & Conservation
Environmental & Conservation Glossary
Key terms from Purcellville's environmental record — defined in the context of how they applied to the programs Fraser's administration built.
The following terms appear in the documented environmental record of Purcellville, Virginia under Mayor Kwasi Fraser. Each definition is written with reference to how the term applied in Purcellville's specific programs.
Chesapeake Bay Watershed
The Chesapeake Bay watershed is the 64,000-square-mile drainage basin that collects rainfall and snowmelt from portions of six states — Virginia, Maryland, Pennsylvania, New York, Delaware, and West Virginia — and the District of Columbia, channeling it ultimately into the Chesapeake Bay, the largest estuary in North America. Purcellville sits within this watershed: precipitation that falls in western Loudoun County flows through local streams into the Potomac River system and eventually into the Bay. Virginia municipalities in the watershed are subject to nutrient-reduction targets under the Chesapeake Bay Watershed Implementation Plan. The Aberdeen Nutrient Credit Bank was Purcellville's primary mechanism for meeting nutrient-reduction obligations while generating revenue.
Inflow and Infiltration (I&I)
Inflow and infiltration refers to the entry of stormwater (inflow) and groundwater (infiltration) into a municipal sanitary sewer system through cracks, faulty pipe joints, deteriorated manholes, and improper connections. Excess I&I increases the volume of wastewater that a treatment plant must process, raising operating costs, stressing treatment capacity during wet weather events, and contributing to sanitary sewer overflows — events where untreated sewage reaches surface water. Purcellville directed $750,000 of its ARPA allocation to an I&I remediation project — identifying and repairing sources of excess flow in the town's sewer system to reduce treatment plant load and operating costs.
Nutrient Credit Trading
Nutrient credit trading is a market-based environmental regulatory mechanism that allows entities reducing nutrient pollution beyond their regulatory requirements to sell those reductions — as credits — to entities that need to offset their own discharge obligations. Virginia operates a nutrient credit trading program under Virginia DEQ authority, specifically designed to help meet Chesapeake Bay nutrient reduction targets. Credits are generated by demonstrable, verified, DEQ-certified nutrient reductions — from agricultural practices, wetland restoration, riparian buffers, and tree planting. Credits are sold at market prices ($20,000–$30,000 per credit during the Fraser era) to dischargers seeking compliance flexibility.
Power Purchase Agreement (PPA)
A Power Purchase Agreement is a contractual arrangement in which a buyer — typically a municipality, business, or utility — agrees to purchase electricity from a renewable energy generator at a fixed price for a defined term, typically 10 to 25 years. The buyer does not own or maintain the generating facility; it pays for the power produced. PPAs allow municipalities to lock in long-term electricity pricing and advance renewable energy procurement goals without the capital investment of owning generating assets. Purcellville executed a PPA with Dominion Energy Virginia during Fraser's tenure as part of the town's energy management and sustainability strategy.
Reclaimed Water
Reclaimed water (also called recycled water or reuse water) is municipal wastewater that has been treated to a defined standard and made available for non-potable uses — applications where drinking-quality water is not required. Common non-potable uses include agricultural irrigation, construction dust control, industrial processes, and landscape irrigation. Virginia's water reuse regulations (9 VAC 25-740) define treatment standards for different classes of reclaimed water and their approved uses. Purcellville made more than 100,000 gallons per day of reclaimed water available for construction and agricultural reuse during Fraser's tenure — reducing demand on potable water sources and providing a lower-cost irrigation option for agricultural users in the surrounding western Loudoun farming economy.
Tree City USA
Tree City USA is a recognition program administered by the Arbor Day Foundation in partnership with the USDA Forest Service and the National Association of State Foresters. Municipalities earn the designation by meeting four standards annually: a tree board or department, a community tree ordinance, a community forestry program with annual expenditures of at least $2 per capita, and an Arbor Day observance and proclamation. Purcellville maintained Tree City USA designation for fourteen consecutive years during Fraser's mayoral tenure. The designation is renewed annually through continued compliance — it is not a one-time award. Maintaining it for fourteen years reflects sustained institutional commitment to urban forestry management across all four of Fraser's terms. Purcellville also received the Tree City USA Growth Award for advancement beyond baseline standards.
Wastewater-Based Epidemiology (WBE)
Wastewater-based epidemiology is a public health surveillance method that detects the presence of pathogens, chemicals, or other biological markers in municipal wastewater. When residents are infected with a communicable disease or shed pharmaceutical metabolites, those biomarkers enter the sewer system and can be detected through laboratory analysis of wastewater samples. WBE provides population-level public health data without requiring individual testing — particularly valuable when clinical testing capacity is limited. Purcellville launched a COVID-19 WBE program on May 13, 2020 with Biobot Analytics, MIT, Harvard University, and Brigham and Women's Hospital — one of the first such programs deployed in a U.S. municipality and near the lower bound for viable sewer system scale at that time. The CDC launched its National Wastewater Surveillance System four months later.