Church in Concord with a broken foundation

Challenge

When we first inspected the Mount Calvary AME Church in Concord (Seaford, DE) with a severely broken foundation it was clear that it needed some kind of supports under the foundation walls. We were told that over the past 30 years it had been repaired multiple times and still continued to sink. We secured architectural drawings of the concrete lentil that was added in the mid 1980's in an effort to strengthen the foundation. After digging out the the dirt around the building, our crews discovered that the lentil was twice the size it was supposed to be and that there was actually a previous attempt at fixing it that we had not heard about. The concrete footer was almost 30 inches down in the ground and roughly 18 inches out, which is much more than the average concrete footer. Our crews worked for 2 full days just to jackhammer and excavate to the base of the structure. It was only then that they begin to install the helical piers to fix the problem.

Solution

DryZone installed seven 287 helical piers, two SmartJacks, and shimmed an existing pier under the church. The helical piers used have an outside diameter of 2-7/8 inches. These piers have a minimum tensile strength of 70 ksi. They were installed to depths ranging from 14 to 28 feet. The SmartJacks are zinc plated to resist corrosion and can hold a vertical load of 60,000 pounds each. The foreman was able to achieve about 4" of lift on the structure. So much so that the windows had to be removed to avoid breaking them during the lifting process.

Project Summary

Engineer: Macintosh Engineering

Architect: French & Ryan

Inspector: Bill Anderson

Project Manager: Kenny Sharpless