A study was conducted for the OJP site situated along the Pacific Coast of Costa Rica in close proximity to the coastline. Thirteen structures, 15 stories high, are planned. Borings were previously conducted and a geotechnical report by others was prepared providing recommendations for piles of various types. The Owner wished to explore other options to reduce foundation costs. An additional complication was the uncertainty about the site resistance to liquefaction. OEI scope included verifying procedure used to advance new borings which was drilling with mud rotary techniques.

Drilling was accomplished by mud rotary techniques, under OEI observation of three (3) borings. From these three borings, undisturbed tube samples were collected as per ASTM D1587 primarily from soils classified as ML or MH. Considering the design earthquake, a ground motion design record was developed (actual record from Costa Rica was used).

Using the data from the borings and laboratory testing results, OEI estimated the dynamic soil properties and conducted amplification studies using SHAKE program to determine shear stresses. Based on the laboratory testing, OEI determined liquefaction potential and developed a remedial scheme to stabilize site. Foundation stabilization was recommended using wick drains and preloading construction is in progress.