Case Studies

Commercial Foundations Case Studies: Newhall WWTF Improvement

Friday, April 1st, 2016 by Frank Schultz


A new blower building was planned at a wastewater treatment facility. The area chosen for the proposed structure was previously used as a lagoon for the treatment plant. The lagoon would be drained and partially filled for the new construction. Deep foundations were specified to support continuous grade beams for the building and three isolated pile caps for the blower equipment. A geotechnical investigation identified a general subsurface profile which included 18 feet of medium stiff clay fill over medium dense sand to a depth of 33 feet below grade. The sand was underlain by stiff to very stiff clay to the explored depth of 50 feet.


Helical piles were selected as the ideal deep foundation solution. The helical pile configuration consisted of Model 288 (2.875-inch OD by 0.276-inch wall) hollow round shaft with a 10”-12”-14”-14” helix plate configuration to support design working loads ranging from 22 to 26 kips. Standard extensions advanced the piles to depths from 19 to 33 feet to achieve torque-correlated ultimate capacities of at least 2.5 times the
design working loads (FOS ≥ 2.5). A safety factor higher than the industry standard of 2.0 was applied to limit pile deflection. The helical piles were fitted with standard new construction brackets to be cast into the grade beams and pile caps. Despite encountering 21 inches of rainfall during  construction, all 75 helical piles were installed within the allotted working time.

Project Summary

Architect/Structural Engineer: HR Green, Inc.

Geotechnical Engineer: Terracon Consultants, Inc.

General Contractor: Ricklefs Construction, Inc.

Certified Pile Installer: MidAmerica Basement Systems

Products Installed: (75) Foundation Supportworks HP288 Helical Piles, 10"-12"-14"-14" Helix Plate Configuration, Installed Depths from 19 to 33 feet, Design Working Loads from 22 to 26 kips

our service area

We serve the following areas

Our Locations:

MidAmerica Basement Systems
4525 Buckeye Street
Davenport, IA 52802

MidAmerica Basement Systems
305 2nd Ave SE #200
Cedar Rapids, IA 52401

MidAmerica Basement Systems
3100 N Dries Ln #201
Peoria, Il 61604