APPENDIX A (continued)
Where? (Mark on drawings.)
(4) What was their appearance?
Have other failures occurred? (Investigate to be sure they were not
Is direct current being used anywhere in this plant or nearby? Get:
Complete information on where and why.
Wiring diagrams and schematics.
Method of grounding.
Are any abandoned facilities located in the vicinity? (Metal pipes,
etc., may be used as ground beds.) Are they connected or to be
connected to anything else?
Are additional facilities planned? (Immediate or long range.) If so,
get the following information:
Type and methods of construction.
How will they be connected to existing facilities?
Will direct current be used?
Field Tests That Should Be Conducted:
Soil resistivity. If site is uniform, take 5-foot and 10-foot (usual
depth of buried structures) readings at suitably spaced grid (20-foot
and 100-foot readings may be required). Do not exceed 100-foot
spacing with vibroground instrument. If route of piping or structure
is known, follow the route. Take readings of fill, if any.
Take pH samples at same places as resistivity, if soil is
Soil samples and water samples (steam riser, etc.). Take samples for
sulfides and sulfate (and pH) at representative grid locations.
(Minimum of six.)
Structure-to-soil voltage (at discretion of engineer):
A thorough test of bare structure requires one over structure and
one on each side every 25 feet.
Coated structure - less frequent readings are needed.