Lompoc Federal Correctional Institution, Drainage Improvements between FCI and Farm Road, Santa Barbara County, California
Fugro provided geotechnical services for the design of drainage improvements at the Lompoc Federal Correctional Institution (FCI). The project involved rehabilitation of an approximately 1,000-foot drainage channel that extends from the south side of the FCI to Farm Road. The lower approximately 400 to 500 feet of the channel have experienced relatively severe erosion. This project involved repairing the drainage channel, and reviewing the grass-lined channel above the eroded areas.

Fugro excavated 2 to 3 backhoe pits along the existing drainage ditch, and drilled hand auger borings in areas that were not accessible to the backhoe. The borings were sampled using a hand driven ring-sampler and by taking bulk samples from the backhoe pits. The pits were backfilled with the excavated soil after the completion of the exploration.

Laboratory tests for compaction, grain size analysis, Atterberg limits, moisture content, and unit weight were performed on selected samples recovered from the field program.

The project report addresses:

• Soil and groundwater conditions encountered;
• Predominant causes of erosion along the existing channel, and the potential for future erosion along the upper grass-lined swale;
• Site preparation, grading and fill placement needed to restore the channel;
• Suitability of on-site materials for use as fill or backfill material;
• Requirements for imported fill materials, if needed;
• Compaction requirements for fill and backfill materials;
• Design of concrete- or geosynthetic-lined channels; and
• Suggested materials specifications for geosynthetics and aggregates.