A new overhead aeration line was constructed to replace a leaking underground pipeline at the Northeast Water Pollution Control Plant. Loads on the two major footings ranged from 227 to 756 kips. Subsurface conditions consisted of miscellaneous fill and loose to medium dense, very fine to medium silty sand to a depth of 20′. Grouted Helical Micropiles (GHM’s) were installed to support the two aeration line foundations. A total of 24 GHM’s were installed to depths of 31.5′.
Project Summary:
- Helical Pile Type: 1.75 “Square Shaft with a single 14″ trailer & a 5” diameter grout column
- # of Helical Piles: 24
- Location: Philadelphia, PA 19137
- Installation Depth: 31.5′
- Challenge/Unique Aspect: A stiff silt was encountered beneath the sand. Groundwater was encountered approximately 12′ below the ground surface. Subsurface conditions consisted of miscellaneous fill and loose to medium dense, very fine to medium silty sand to a depth of 20 feet. Helical piles had to be located around numerous existing underground utilities, obstructions, and deal with overhead clearance problems.
- Engineer/Architect: Malcolm Pirnie
- Geotechnical Engineer: Underwood Engineering Company
- General Contractor: C&T Associates
- Owner: Philadelphia Water Dept.
