The Stringfellow acid pits near Glen Avon could be cleaned up in less than half the time suggested by a state-sponsored report, a consultant hired by nearby residents said. Robert Powell, of the Washington-based Environ Corp., suggested a 14-year plan and a 32-year plan for cleaning up the pits. Powell’s plans call for excavating and treating about 2.7 million tons of contaminated soil at the Pyrite Canyon dump site in Riverside County. The state study, describing a similar method, estimates that the cleanup will take at least 63 years. The state study also described other methods requiring between 55 and 448 years. “If you go in with a more aggressive program, the cleanup may be (done in) half the time predicted in the (state report),” Powell said. About 34 million gallons of acids, pesticides, solvents and toxic metals were dumped at the site between 1956 and 1972.