Septic systems questioned on $700K homes in Alexandria Township

The Delaware Valley News

Thursday, July 14, 2005

By John Monteith

Septic systems dug into bedrock beneath a thin layer of soil could mean that future homeowners in a development now being built in Alexandria Township could end up drinking water tainted by their own sewage.

That's according to a hydrologist hired by the township Environmental Commission after resident Robert Reid studied soil logs for "Alexandria Estates."

The development was approved in October, following Planning Board hearings that included heated exchanges between some board members and Toll Brothers attorneys. Toll Brothers plans 64 clustered houses, each on 1.5 acres, on both sides of Route 513, east of the intersection of Mechlin Corner and Hog Hollow roads. The rest of the 396-acre property would remain as open space, although much of is wetlands.

According to his report, nitrates in the septic effluent will also affect the quality of water in a nearby "trout production" stream.

The open-space land at the site can not contribute to nitrate dilution of the water supply because the elevation is lower than the septic system disposal area and is composed of wetlands, the report continued.

"Reports of up to 40 percent failure of coliform tests in adjacent Franklin Township have been recorded since 1999," said the report. "The failure rate has remained fairly constant through the period. Franklin Township is an area of similar geologic features..."

The approval given the development by the state Department of Environmental Protection did not take into account a report by Planning Board consulting hydrologist Matt Mulhall that exposed a serious error in the nitrate dilution calculations of Toll Brothers hydrologist Converse Consultants, Demicco said.

Converse, he said, based his calculations upon a daily septic effluent discharge of 16 gallons-per-day, which would require at least 1.34 acres per building site. Mulhall, he continued, used a "more appropriate" estimate of 80 gallons-per-day for each resident, calculating that 6.7 acres per house is needed at that site. Demicco felt that the minimum acreage for each house should be 7.3 acres.

The Mulhall report was not reviewed by the DEP prior to approving the development, said Garay. Nor was a townwide water study subsequently conducted by Demicco for the Environmental Commission.

Demicco's study, said Garay in her letter to Campbell, raised serious concerns "about the density allowed in this subdivision and its underlying geology, resulting in almost certain nitrate contamination in the wells of the homes built in this subdivision."

"We're bringing to a higher authority a health issue," she said.

The township Environmental Commission sent a letter last week to state Department of Environmental Protection Commissioner Bradley Campbell, seeking a reassessment of the Toll Brothers approval.

"We realize that this request comes to you late in the process," wrote Michelle Garay, commission chairwoman, "but... we must ask you to intervene on behalf of the families that will soon live in these homes, the C-1 stream that flows through the area of this project, and the underlying aquifer."

Studying the soil logs, Reid said that he found several instances in which water emptied rapidly from septic pits during testing, signifying inadequate filtration. In other instances, he said, the length of drainage time was undetermined because pits were filled in the late afternoon and left to drain overnight.

Essentially, said Reid, the site's water supply is stored in fissures in bedrock beneath a thin soil layer. Building septic systems into the bedrock, as Toll Brothers proposes to do, would jeopardize the quality of the water supply, he said, adding, "Sixty-five septic systems and wells on 1.5-acre" lots is a "recipe for disaster."

The Environmental Commission hired hydrologist Peter Demicco of Franklin Township to review Reid's findings. "In our opinion," Demicco wrote in a June 19 report to Garay, "the wells at Alexandria Estates would be subject to bacteria contamination from the construction of the septic systems into fractured rock substratum... Select fill may, under normal circumstances, hold and retain bacteria. However, recent coliform data suggest that under specific circumstances, such as several inches of rain over a short duration, the movement of water through the select fill promotes migration of bacteria from the fill into bedrock fractures. Movement of viruses will also occur into the fractured bedrock substratum."

Heavy downpours could "flood the aquifer with bacteria," said Demicco on Monday.