How The Dwyer Company Supported Two New Staircases at the Montgomery County Jail
- Project Type: Commercial
- Project Services: Deep Foundation Systems, Helical Piles
Montgomery County Jail added two staircases to its existing structure in Dayton, Ohio, on ground carrying 7 to 14 feet of existing fill over dense soils. The Dwyer Company installed heavily loaded helical piers to take the staircase foundations below that fill, working with general contractor Granger and engineer Shell & Meyer. The design called for 55 piers supporting between 35 and 65 kips, and six more went in as site constraints and varying soils came to light. The full scope closed in two weeks.
High loads landing on fill, with buried utilities in the way?
Quick Facts
- Dayton, Ohio
- Project Type: Commercial – New Construction
- Timeline: 2 weeks
- Owner: Montgomery County Jail
- Structure: Two new staircases adjacent to the existing building
- Foundation System: Helical piers, 55 designed with 6 added in the field
- Pier Capacity: 35 to 65 kips
- Soil Conditions: 7 to 14 feet of existing fill underlain by dense soils; conditions varied from the borings
- Site Conditions:Existing tunnel and electrical ductbank near the work area
- Partners: Granger (general contractor), Shell & Meyer (engineer)
The Challenge
Two staircases bring heavy loads down to a small footprint, and the ground at those locations carried 7 to 14 feet of existing fill over dense soils. Conventional foundations would have landed on that fill, which is what ruled them out. The staircase foundations had to bear on the dense material underneath.
The surroundings raised the difficulty. An existing tunnel and an electrical ductbank sat near the work, so pier locations had to clear both. The soils then came back different from the borings once installation started, which meant reworking pier design in the field with the schedule still running.
Key Project Details
helical piers designed for the two new staircase foundations
additional piers added in the field for site constraints and varying soil conditions
The Solution: End Bearing Helical Pier Foundation System
The Dwyer Company installed heavily loaded helical piers under both staircases, each designed to support between 35 and 65 kips. The piers advance through the 7 to 14 feet of existing fill and land in the dense soils beneath it, which keeps the staircase loads off material no one could count on.
Conditions changed the count. Site constraints and soils that differed from the borings brought six more piers into the layout beyond the 55 designed. Dwyer worked each change through with Granger and Shell & Meyer as it surfaced, engineering on the fly to protect both the schedule and the capacity the staircases needed. Two weeks covered the whole scope.
The Impact
Load carried to dense soils
Every pier advanced past the existing fill to the dense material below it.
Buried infrastructure cleared
Pier locations were set clear of the existing tunnel and the electrical ductbank near the work.
Design adjusted in the field
Six piers were added beyond the design as conditions came to light, keeping capacity where the staircases needed it.
Two weeks start to finish
The full pier scope closed in two weeks, changes included.
Why Helical Piers?
Helical piers let The Dwyer Company put heavy staircase loads on dense soils under 14 feet of fill, on a site with a tunnel and a ductbank to work around.
- High capacity per pier – Piers can be designed well into the tens of kips, which suits concentrated loads on a small footprint.
- Installed to capacity – Each pier advances until it meets its design load, so soils that differ from the borings do not stop the work.
- Precise placement – Compact equipment sets piers clear of buried tunnels, ductbanks, and other existing infrastructure.
- Quick to install – Piers reach capacity as they go in, which keeps foundation work off the critical path.
Why Choose The Dwyer Company for structural integrity?
Deep History • Solid Choice
The Dwyer Company’s proven track record in commercial and industrial foundation systems made us the trusted partner for the new staircases at the Montgomery County Jail. Working alongside Granger and Shell & Meyer, our crew adjusted the pier design as the ground revealed itself and finished the foundations in two weeks.
Have heavy loads landing on fill at an operating facility?