Two California developers and a contractor accused of violating air and water pollution laws by blasting asbestos-bearing hills have reached a $350,000 settlement with prosecutors. They will not face charges on 47 incidents documented by inspectors from the El Dorado County Air Quality Management District of explosions that produced thick clouds of dust well beyond the site. Developers Angelo K. Tsakopoulos and Larry Gualco, and DeSilva Gates Construction, Dublin, Calif., soon will meet with air quality officials to refine protocols for subsequent work. The developers and contractor did not admit liability. According to terms of the settlement, DeSilva Gates is solely responsible for payment.