Underwater Tunnel: Microtunneling the ENMRWS Raw Water Intake Tunnel at Ute Reservoir

摘要

Steady declines in water levels of the Ogallala aquifer, which is the sole source of municipal and agricultural water inrnmuch of eastern New Mexico, has led to critical water shortages in the region. To relieve the shortage, the EasternrnNew Mexico Rural Water System (ENMRWS) project was developed. The Ute Reservoir in Quay County, NewrnMexico is the intended source water supply for the New Mexico communities that make up the Eastern New MexicornWater Utility Authority (ENMWUA). The ENMRWS conveyance system comprises raw water pipelines, raw waterrnpump stations, a storage reservoir, a water treatment plant, a finished water pump station, and additional finished waterrnconveyance pipelines. A key component of the system and the first stage to be constructed is the new Ute Reservoirrnraw water intake, which includes a 50-foot diameter pump forebay shaft and a 233-foot-long intake tunnel. Subsurfacernconditions at the intake site include sandstone bedrock with jointing that is in direct connection to the reservoir. Thernpump forebay shaft was completed with controlled blasting techniques in conjunction with water control grouting.rnFrom the shaft, a 60-inch intake pipe was tunneled using microtunneling and pipe jacking to a newly constructedrnunderwater bench within Ute Reservoir. The paper presents construction challenges and on-site observations relatedrnprimarily to the implementation of a microtunneled intake with the successful subaqueous recovery of the tunnelingrnmachine.