NCA EBRP GPS installations: San Andreas Mega Cluster

Overview

June 02, 2005

PBO’s Northern California region just finished a number of GPS installations throughout the East Bay regional parks (EBRP). Bulk permits for 10 GPS sites were obtained from EBRP and eight stations have been installed, three of which are deep drill braced monuments.

As part of their busy installation schedule for year 2 of the PBO project, the Northern California region has installed a total of 40 GPS stations (including the East Bay parks) since this writing. Unseasonably wet weather during the late winter kept installation teams from making as much progress as planned. Regardless, crews continue to chop away at their installation goals, doing as much work as possible during the rainstorms that generally hit twice a week and often last two to three days. Short-drill monuments are generally easier to install during the storms since the epoxy is able to dry at a faster rate than on deep-drill installations, less equipment is needed for the installation, contract drillers are not required, and the crews are able to mobilize between sites faster. When the weather breaks, grateful installation teams quickly head out to finish any weather-sensitive site work. To ensure the steady flow of work never ceases, the four Northern California GPS field engineers alternate taking trips into the field, catching up on the never-ending installation documentation while at the PBO office located in Richmond, California.

The inclement weather brought some unexpected circumstances. Because of anticipated stormy weather, a group of three engineers were able to complete a deep drill based monument in one day. Working non-stop from dawn to dusk, the team finished the site in 12 hours; normally, it takes 2 days to complete a deep drill installation during good weather. Another group was turned away from entering the Santa Clara Water District because of the heavy rains creating unstable grounds. It wasn’t until the crew arrived at the entrance, installation equipment in hand and ready to start drilling, that they learned about the problem.

A second hurdle to overcome when planning the installation schedule is the permitting process. It normally takes six weeks to a year to receive a permit once the application has been submitted. Balancing the timing of the permits with the dates of the installations is a tricky equation, but one that the regional engineers are getting to know very well. Currently, permitting activities in the Northern California region include the following areas: Caltrans District 10, District 5, Pit River Tribe (Medicine Lake), Whiskeytown National Recreation Area, Lassen (most active volcano in CA), Parkfield (PBO Nucleus stations), and Hayfork and Weaverville airports.