Impermeable

The yoga regulars whisper about the Baptists before the morning class.  Neighbors charge into City Council chambers, demanding redress even before the flooding starts.  Small business owners shake their heads at the signs that read “Church Parking Only.”

The transition from a green lawn to an asphalt parking lot was almost inevitable.  The church had owned the acre-sized lot on Main Street since 1945, first relocating a wooden Army chapel to serve as their sanctuary.  The lot remained green and permeable, serving as an area for games, gatherings, and special events for the church and small town festivals.  As many of the parishioners moved away from Old Town, beyond walking distance, it was inevitable that the lawn would serve as overflow parking on Sundays.  The structure flooded in Hurricane Katrina, and the congregation made the choice to grow, replacing the historic structure with an expanded sanctuary built in the classical brick that is a hallmark of southern Baptist churches.

There were complaints about muddy shoes and slippery paths.  The grass grew patchy and rutted from the springtime rains.  The lot was spread with gravel, pieces of limestone as big as a fist, compacted to form a stable base for automobile tires, if uncomfortable for little people and dainty shoes.  The gravel was still permeable to stormwater, a necessity in a place which receives over 67 inches of rain each year and a flat, coastal plain with no appreciable slope for water to drain.

Last month saw the inescapable culmination of this preparation, the paving of the lot from the building to the property line.  The gravel was a good base, well-compacted after a year of use.  The black tar stretches to the street, leaving only a narrow fringe of non-native crepe myrtles to appease the Historic Commission and the City Planning and Zoning officers.  There wasn’t any legal reason to halt the paving – no appeals, no aesthetic controls, and no requirements for site infiltration in the C-1 Central Business District.  When the public protested, the argument given by the church was an economic one – We can’t afford to do anything to beautify the site, because we are spending all of our money on paving.

Churches are required to provide 1 space per 5 seats, and if each seat occupies 20 SF, this effectively requires 1 parking space per 100 square feet of building area.  One parking space equals 300 square feet (driveway, aisle, and parking) at the highest design efficiency, thus tripling the building footprint on the site.  Public sentiment against minimum parking standards is rising; urban scholars contend that extended parking lots hinder walkability and create barriers to local business startups.  At the same time, the number of cities that require properties to capture the first inch of stormwater on site are growing.  Together these trends should create a convincing argument for cities to draft stronger policies against the conversion of green space to parking lots.

Help comes too little and too late for this site, and for its neighbors who will be subjected to significantly higher runoff from this site.  The National Stormwater Calculator identifies the average annual rainfall as 67.37 inches, and estimates the average annual runoff (the water leaving the site) at 91 percent, or 61.67 inches.  With zero infiltration through the asphalt, the little relief will be produced by evaporation.  Nearly 62 inches of rain per year, multiplied by 29,185 square feet of impervious surface, equals over 150,000 cubic feet of water leaving the site or 1,127,980 gallons per year.

Over one million gallons of additional rainwater for the neighbors to deal with: splashing over their steps, swirling around their drain inlets, swamping the streets and passing cars.  An extra million gallons flushed into the Gulf of Mexico with no pre-treatment for the contaminants the stormwater will pick up in the parking lot: sediment, oil, antifreeze, insecticides, lead, fertilizer, and other urban emissions.

All of these impacts could have been avoided through better design choices.  Permeable pavers, infiltration strips, pervious concrete, grass paving and other low-impact systems are proven to retain a percentage of infiltration capacity in parking areas , efforts that would have resulted in reduced impact for the church’s neighbors but still kept the congregation’s feet dry.

The short-term solution has created strong feelings of mistrust and resentment in this small town, even before an intense rainfall event has tested the parking area’s effect on drainage.  When it does, public recriminations are certain to follow – but the lot was paved according to the current ordinance adopted by the city.  Is it legal? Sure.  Is it desirable? No.  And it doesn’t sound much like stewardship.