The oil company ConocoPhillips this week began cleanup of an oil spill in Nipomo Creek near the Dana Adobe. The excavation work — monitored here Thursday by senior project manager Rick Brown — is expected to take about eight weeks to complete. In 2003, a crude oil pipeline leaked, contaminating a 300-foot area of the creek. The pipeline has since been repaired. The leaked oil is 2 to 4 feet below the creekbed. That material is being removed to prevent it from being washed downstream. The excavated area then will be backfilled and replanted with native trees and shrubs.