The major target of his concern, said Turner, is a proposed expansion of the Downingtown Area Regional Authority's (DARA) sewage treatment plant that would increase the amount of waste water discharged into the east branch of the Brandywine Creek.
"We must view any effort to increase that discharge with considerable apprehension," Turner said in his Jan. 9 letter.
He said that even at the current rates of discharge, there were several indications of the stream's deteriorating quality, including a 100 percent increase in the levels of phosphorous from 1986 to 1988. Phosphorus, a component of fertilizer, can upset the ecological balance in a stream by causing excessive plant growth that robs other stream organisms of oxygen.
The stream is the sole source of water for both Wilmington and the West Chester Area Municipal Authority, another agency that has criticized the plan, which calls for an increase in treatment capacity of 7 million to 8.8 million gallons daily.
Currently, the plant is processing an average 5 million gallons each day.
One answer to Wilmington's dilemma, said Turner, is for DARA to turn to the most advanced methods of waste-water treatment and cut back on the amount of nutrients going into the stream.
Turner said he supported the recommendations of a consortium of Chester County environmental groups who say increased sewage capacity for the Exton region can be achieved by using spray irrigation of treated waste water and other land-application methods instead of discharging effluent directly into the stream.
The proposal, however, while endorsing these methods for some parts of the region, rejects a wholesale adoption on the ground that such disposal is too expensive because of the high costs of land acquisition.
An outspoken critic of the expansion plan, H. William Sellers, director of the Brandywine Conservancy's Environmental Management Center, said this view was short-sighted.
"There are costs that are going to be incurred over time that haven't been adequately addressed," said Sellers Monday night at a meeting of the DARA board. Sellers said he wanted to be sure officials understood just what they were getting into if conventional treatment methods continued to be used.
"You're taking a Model T and trying to make a modern car," he said, "and it won't work. We're not out to kamikaze you. We want to find a solution we can live with for a long time.
Sellers also criticized DARA's planning committee and its engineer for failing to address comments and suggestions that the consortium has made during the last three years that the plan has been in preparation.
The DARA directors have given themselves two weeks to review the controversial expansion plan before deciding when they will release the document to the public. The board will conduct a special meeting Feb. 4 to either fine-tune the plan or release it "as is" for the required 30 days of public comment before public hearings begin.
Although final approval rests with the DER, the environmental consortium has threatened legal action to block the plan if it is approved in its current form.