OUR BLOG: INSIDE THE LIFT

27Jul 2015

Rehabilitating Soils to Increase the Bearing Capacity Under Milk Storage and Grain Handling Facilities

By Susan Albershardt

Silos are storage systems designed to contain massive amounts of weight within a concentrated area and vary in size, ranging from 20-80 feet tall with diameters of 12-30 feet. Some storage facilities have more than one or two silos sitting in a small area.  When the silos are full, the significant weight can impact settlement of the foundation and/or the foundations of nearby structures.

In addition to the consolidated weight of tanks that hold liquid and grain storage bins, the surrounding processing facilities get a lot of traffic as well. There is a constant stream of trucks, mostly loaded with heavy cargo, coming and going from the facility. When there is a rail spur next to the facility, the soils underneath and around the grain bins, silos, and mission critical buildings are taxed with even more weight.  Consequently, there is a lot of weight consolidated into a relatively small area around these crucial, very busy facilities.

After heavy rainfall like we have seen across the United States in the last few weeks, we start seeing the effect on the infrastructure of the slabs and tunnels underneath these facilities becomes apparent. If there are flaws in the design or construction of the facility, or poor compaction of the soils underneath, over time the cement slabs will settle causing minor damage, such as cracked pavements, to major issues, like warping of silo walls, bent metal interfering with the operations, separation of conduit, ponding water and water accumulation in the boot pit.

URETEK Holdings has rehabilitated the bearing soils at several different commodity holding and transferring facilities. Here are some example of completed projects:

URETEK's rig parked outside facility
URETEK’s rig parked outside facility

At one project in Murray, Kentucky, the foundation pad underneath a 50,000 gallon milk tank was settling due to a high water table and fine grain soils underneath the tank’s pad.  Settlement was also affecting two of the mission critical adjacent buildings.

Stabilizing weak soils under foundation pad of 50,000 gallon milk tank.
Stabilizing weak soils under foundation pad of 50,000 gallon milk tank.

The URETEK™ Deep Injection® Process using high-density structural polymers was used to stabilize and bridge the weak soils at two different depths beneath the pad. The design of the injection plan allowed the densified soils to bridge over the weaker soils at depth.  This approach was more time-effective,cost-efficient and less problematic than using cementitious grout.  URETEK’s method rehabilitated the load bearing capacity of the soils while injecting just over 7,000 lbs of material, whereas using cementitious grout would have added 25 tons of overburden to the already compromised foundation soils.

URETEK technician injecting inside the facility.
URETEK technician injecting inside the facility.

During URETEK’s installation, production at the facility continued as normal.  In fact, the tank was filled and emptied three times each day without any interference at all. The tank pad has been monitored for the past two years and there has been no additional settlement.

URETEK technicians injecting through the pad on the exterior of the silo.
URETEK technicians injecting through the pad on the exterior of the silo.

At another project in Canton, Kansas, a grain handling facility was experiencing some settlement in several areas due to poorly compacted soil and drainage problems.  The settlement caused a joint to separate in the boot pit housing the elevating equipment and water was pooling on the floor.

Rail spur leading to grain loading terminal.
Rail spur leading to grain loading terminal.

URETEK was called in to use its Deep Injection® Process to rehabilitate the load bearing capacity of sub-soils under the Motor Control Center (MCC), the rail car loading area, and the approach slabs to the truck unloading area, as well as seal the leaking joint in the boot pit – all without disturbing the operations of the facility. Kevin Stumpff, URETEK’s project manager (kevin.stumpff@uretekusa.com), worked closely with the operation’s personnel at the facility to ensure that the trucks and trains loading and unloading the grain were unaffected by URETEK’s installation and there was zero facility downtime.

URETEK’s successfully stabilized the sub-soils and filled the voids underneath the grain loading facility, preventing further damage to the facility and its buildings.  The work was completed within budget and without interfering with the facility’s operations.  Great job, team!