Soil Stabilization Saves Historic Mansion in Iowa

Problem

The elegant Henn Mansion, located in Fairfield, IA, was originally built to be the home for the President of Parson’s College in 1857. In 1983, the mansion was added to the US National Historic Register, and today the building serves as the Human Resources office for Maharishi University. Over the years, soils beneath the building’s foundation became weak and the building began to settle with serious cracks developing at the southeast corner.

Analysis

Back in 1857, the footing of Henn Mansion was designed as a “continuous” footing.  That means the limestone rock used as the footing is in continuous contact with the soils below. The settlement of the building’s foundation was caused by the loss of support within the soils under the continuous footing. Since the building’s footing was constructed of limestone rock, it couldn’t be repaired with traditional pier methods since there is no place to attach the anchor brackets. Another consideration involved the fact that the building is in active use as a university administrative office, and needed to remain open, if possible.

Solution

The university contacted URETEK to asses Henn Mansion’s foundation issues. After careful evaluation, the URETEK Deep Injection® (UDI) process was selected to stabilize the foundation, as it is ideally suited to fill voids, stabilize soils below various foundation types, and lift foundations when required. URETEK informed university officials that the building could remain open for business during the scheduled repairs.

Result

URETEK successfully restored the soil’s ability to support the structure’s continuous footing. During the repair, lasers sensitive to 1mm of movement were attached to the building. When movement was registered by the lasers, injection ceased as the soil was now sufficiently densified to support the load of the structure’s southeast corner, and to prevent the exterior ladder cracks from stretching further. The repair was completed in less than 48 hours. URETEK’s repair process was quick, clean, caused little to no disruption, and most importantly helped save the historical building in its original state.

URETEK Deep Injection® (UDI)

Widely referenced throughout our industry, UDI involves the injection of structural polymer into base and subgrade soils to increase the load bearing capacity. This is achieved by injecting the polymer through small holes drilled directly through the pavement structure to depths determined by site-specific analysis. Our URETEK 486 Star® material flows easily into voids and weak zones within the soil mass below. Through a controlled chemical reaction, the expanding polymer compacts surrounding soils and applies a controlled pressure on targeted areas of the affected pavement above. If needed, a multi-injection design plan is utilized to gently return the pavement to its original grade. The composite material quickly cures into a strong, dimensionally stable, and water-resistant geo-material, providing years of reliable service.

URETEK 486 Star®

URETEK 486 Star® polymer is a two-component, high-density, expanding thermoset polyurethane system. It was developed to be the ideal solution for under-sealing, void filling, lifting of settled pavement, stabilization and stiffening of weak soils, and for encapsulating and sealing buried infrastructure. URETEK 486 Star® is environmentally inert, non-toxic, and resists underground water erosion or weakening due to its industry-leading hydrophobic properties.

Over the years, soils beneath the building’s foundation became weak and the building began to settle with serious cracks developing at the southeast corner.
URETEK crew working to fix the Henn Mansion