Structure excavation & Backfill Flashcards
What material is to be used flowable backfill be used around structures.
NO–> Only for VERY special cases
Moisture content for backfill material
Looking for shiny, sticky, muddy and holds shape well.
What question should I be asking as I look at backfill material?
Is clay content high in this material?
Any indication of expansive soils?
BEFORE DIGGING WHAT NEEDS TO BE DONE?
Dig Alert submitted 2 full working days before operation
delineated high risk utilities
How far back are spoils from edge?
2 ft
Competent Person
Inspects face for failure
Enforses CSO
Enforces submittals
How deep of excavations are allowed before needing to follow OSHA regulations?
5 ft
Egress Rules
-4 feet or deeper, need egress ever 25 ft
-3 feet above grade for ladder
5-4-3-2-1 pneumonic
5-anything over 5 feet needs a plan stamped by an engineer
4-anything deeper than 4 needs a degree every 25 ft
3-The egress ladder needs to extend 3 ft above grade
2- spoils are 2 ft away from excavation
1- one competent person
If the buried man-made object is discovered and is not shown on the plan
Change Order work
When to take photos
Prior to excavation operations
Is the bottom of footing for any structure final?
No, it is approximate.
Slurry backfill is defined as
2 sack cement
Sand Equivalent Definition
Sand vs Clay ratio per CT 217
Beyond structure backfill graduation requirements and compaction requirements
100% passing 3” and 90% compacted
Thickness of lifts
8”
Do not place backfill against structures until they have reached a compressive strength of?
2,500 PSI
When backfilling an abutment, what needs to be placed on bridge’s back wall for protection?
bumpers
Is compaction method damaging the structure?
What is compaction below approach slabs or sidewalks, or roadway?
95% to a distance of 2.5’ below these surfaces. But is 95% under all approach slabs. full width and depth due to compaction specifications.
How far back is 95% compaction from the centerline of the abutment?
150 ft
