Structures Detailing Manual | Jan 2008
7 - Core Borings |

# 7 - Core Borings

## 7.1 General

A. This drawing, prepared by the District Geotechnical Engineer or a Consulting Geotechnical Firm, is a graphic portrayal of the subsurface conditions at the project site.

B. The information presented on this drawing and in the Geotechnical Report is used to arrive at a proper foundation design.

## 7.2 Scales

A. Draw the boring layout plan and boring logs in elevation to a scale large enough to legibly show the data and permit reasonable determination and interpretation of soil strata variations.

B. The vertical scale of the boring logs must be large enough to permit inclusion of all relevant boring data and need not be the same scale as the boring layout.

C. Selected scales must provide 100% legibility when reproduced to 11-inch x 17-inch prints.

## 7.3 Check Items

The following data should appear on the drawing:

A. Plan View (Boring Layout):

1.) Station Line (show station values at 100-foot increments).

2.) Station Line label (Base Line Survey, Center Line Construction, etc.)

3.) North Arrow.

4.) Begin and end bridge stations and labels.

5.) Boring locations referenced to station line by station and offset.

6.) Boring labels.

B. Elevation View (Boring Logs):

1.) Elevation reference (vertical scale) on both left and right side of sheet (borings must be plotted in reference to elevation, not depth below ground surface).

2.) Boring plots, labels, stations, offsets. (Use the soil-type symbols specified in the current Soils and Foundations Handbook)

3.) Ground surface elevation.

4.) Ground/surface water level and date recorded (note elevation of artesian head if encountered).

5.) Strata description including Unified Classification Symbols.

6.) Standard Penetration Test (SPT) N-values.

7.) Rock Core Locations, % recoveries, RQD.

8.) Undisturbed soil sampling locations.

9.) Lab test results.

10.) Insitu test locations (vane shear test, dilatometer test, pressure meter test, etc.) and corresponding test results.

11.) Note unusual circumstances such as: sudden drop of split spoon, loss of circulation, etc.

C. Other:

1.) Soil Legend.

2.) Rig Type.

3.) SPT Hammer Type.( Safety Hammer or Automatic Hammer.)

4.) Environmental Classification (superstructure, substructure).

5.) Financial Project ID.

6.) Completed Title Block.

## 7.4 Title Block

A. The title of this drawing is "REPORT OF CORE BORINGS".

B. Show the names of the drillers who performed the borings, and the responsible Geotechnical Engineer.