In May 2000, an out-of-control prescribed burn near Los Alamos, New Mexico, destroyed more than 47,000 acres, severely affecting the Pueblo Canyon watershed, which lost vegetation and caused a substantial increase in runoff and channel flows. Subsequent rains damaged more than 2,000 linear feet (lf) of sewer pipeline and caused raw sewage discharges to the canyon's streambed.
Los Alamos County enlisted CDM to design the replacement and relocation of 15,000 lf of sewer pipeline in 12 months—to be completed before the next monsoon season. Within 14 weeks, CDM oversaw completion of aerial photography, topographic mapping, geotechnical investigations, and an environmental assessment. For the fast-track implementation, CDM selected microtunneling to safeguard the canyon's fragile rock formations, called "hoodoos," and its 200-year-old Ponderosa Pines. Underground installation at Pueblo Canyon required 36 separate bores, each accommodating 100- to 500-foot sections. Inside the small jacking pits, located 200 feet or more below the canyon's surface, tunnel boring machines excavated the soil while simultaneously installing new steel pipe casing. Once completed, natural vegetation was replanted over the jacking pit sites.