Project Scope

Jaca & Sierra Engineering, PSC was contracted by The Dominica Geothermal Development Company (DGDC) to perform site investigations for the proposed 7MW Geothermal Plant at the Roseau Valley, Dominica. The project consisted of two phases: the power plant site located at Laudat; and the brine reinjection line extending from Laudat to Wotten Waven and Trafalgar.

Geotechnical Laboratory Testing

The collected soil samples were delivered to our laboratory to perform analyses of moisture content, unconfined compressive strength tests, soil classifications, California Bearing Ratios (CBR), compaction test, and uniaxial rock compressive strength tests.
Additional field testing included one (1) downhole seismic test and eleven (11) Dynamic Cone Penetration tests.

Drilling and In Situ and Field Testing

In-situ testing and soil sampling was achieved by means of the Standard Penetration Test (SPT) and split spoon sampler method according to ASTM D 1586. Rock core drilling was achieved according to ASTM D2113. Subsurface drilling was executed by means of the HW casing advancer system and HQ wireline rock coring per ASTM D 1452 using a trailer mounted CME-55 hydraulic rotary drill.
A total of seven (7) borings were performed throughout the site: three (3) at the Power Plant Site; and four (4) at the Reinjection Route. Boring depths varied from 20 to 100 ft. Rock coring required drilling thru highly weathered volcanic boulders followed by overburden soils. The borings were located on areas of extremely difficult access covered by dense vegetation and boulders, that required