Characterization

SITE CHARACTERIZATION is the first step in geotechnical and environmental assessments. Our objective is to obtain adequate information to meet the CLIENT’S NEEDS in a cost-effective manner. 

This involves more than just drilling holes!  

Click below to view “Geologic Cross Sections” that illustrate our interpretation. 

       

Stratification

PCC geotechnical reports often include “Geologic Cross Sections” similar to the examples shown above.  Our interpretation of subsurface conditions may be illustrated by separating soils and rocks of similar engineering properties into strata. Vertical and horizontal variations are natural. Strata changes may be gradational or inter-bedded as illustrated in the complex stratification. The engineering properties of interest depend on the particular project. Strata may be drawn differently using the same data. For example, the characteristics of interest for construct of a dam may be different than for support of a building or road.  

The following outlines some the basic considerations in design of a site characterization. 

Project Characteristics

It is of little value to drill test borings 10 feet deep in soft soil conditions if the basement floor will be 15 feet below present ground surface. Preliminary Phase services are typically provided for the purpose of assisting with overall project planning and budgeting. This may include Environmental Site Assessments and/or Preliminary Geotechnical Services. Basic information needed includes; client contact, property location and boundaries, intended property use, etc. Geotechnical Design Phase Services are typically provided after property acquisition and selection of the design team. Typical information needed includes concept plans. Construction Phase Services are provided during construction. Typical information needed includes; site plans, foundation plans, contact names, etc. Unanticipated subsurface conditions are always a possibility and may lead to extra costs during construction. Professional Consulting Corporation offers continuity of professional services to help the CLIENT through the entire construction process. Forensic and Expert Witness services are offered to assist the CLIENT in evaluation and remediation of geotechnical or environmental concerns.

Geologic Setting

Site characterization starts with geologic research and reconnaissance. In areas of uniform geologic conditions less subsurface exploration is needed than in areas that are likely to exhibit significant changes in short distances. PCC maintains geologic maps, soil maps, topographic maps, databases, library and electronic references. These tools may be used in combination with the extensive local experience of our professionals in preliminary geologic site assessment and design of the subsurface exploration and site characterization. 

Subsurface Exploration

Geotechnical exploration usually includes test borings with Standard Penetration Tests (SPT) at regular depth intervals. This type of exploration provides an indication of the soil or rock types and relative density or consistency at the depths and locations tested. Bulk samples, Shelby tube samples, core samples, etc. may be utilized to obtain samples for specific types of laboratory testing. Laboratory tests are usually performed to evaluate material properties. In-situ testing or monitoring, geophysical surveying or other specialty applications may be used. Test pits and hand auger test borings with Dynamic Cone Penetrometer (DCP) testing, Shelby tube and/or other sampling and testing techniques are often used for projects involving forensics.