Replacing Intake Pumps at Lake Arrowhead

September , 2018

Working with Trinity Construction for the Lake Arrowhead Community Service District in California, Global provided all diving and underwater construction support for the replacement of the community’s aging freshwater intake system. Dive crews performed the sinking and installation of over 500’ of new HDPE conduit PLEM (pipeline end manifold) that branch into three underwater concrete vaults; the vaults house new 34.5 hp HOMA intake pumps.

Operating from a dive barge at the location, the divers closely worked with the crane operator to assist in the sinking and placement of the pipeline and concrete vaults. Once the three 45,000 lb concrete vaults were carefully lowered into position under the direction of the dive team, the divers installed the spool pieces tying the system together. Clear communication was crucial between the divers in the water and the topside crane team in order to place the large vaults on the lake bottom without damaging them or injuring the divers. After the intake pumps were installed, the system was tested and brought online.

The project site presents several logistical challenges; Lake Arrowhead is a remote lake situated in the San Bernardino Mountains in California and required trucking several oversized loads up narrow mountain roads. Because of the lake’s 5,100 foot elevation, the divers’ maximum bottom time was restricted to 70-90 minutes and surface decompression was used. Working a 10-hour shift Monday through Friday, Global safely logged over 80 dives to perform the required installations.