Applications for Reuse of Lime Sludge from Water Softening, TR-535, 2005

Lime sludge, an inert material mostly composed of calcium carbonate, is the result of softening hard water for distribution as drinking water. A large city such as Des Moines, Iowa, produces about 30,700 tons of lime sludge (dry weight basis) annually (Jones et al., 2005). Eight Iowa cities representing, according to the United States (U.S.) Census Bureau, 23% of the state’s population of 3 million, were surveyed. They estimated that they collectively produce 64,470 tons of lime sludge (dry weight basis) per year, and they currently have 371,800 tons (dry weight basis) stockpiled. Recently, the Iowa Department of Natural Resources directed those cities using lime softening in drinking water treatment to stop digging new lagoons to dispose of lime sludge. Five Iowa cities with stockpiles of lime sludge funded this research. The research goal was to find useful and economical alternatives for the use of lime sludge. Feasibility studies tested the efficacy of using lime sludge in cement production, power plant SOx treatment, dust control on gravel roads, wastewater neutralization, and in-fill materials for road construction. Applications using lime sludge in cement production, power plant SOx treatment, and wastewater neutralization, and as a fill material for road construction showed positive results, but the dust control application did not. Since the fill material application showed the most promise in accomplishing the project’s goal within the time limits of this research project, it was chosen for further investigation. Lime sludge is classified as inorganic silt with low plasticity. Since it only has an unconfined compressive strength of approximately 110 kPa, mixtures with fly ash and cement were developed to obtain higher strengths. When fly ash was added at a rate of 50% of the dry weight of the lime sludge, the unconfined strength increased to 1600 kPa. Further, friction angles and California Bearing Ratios were higher than those published for soils of the same classification. However, the mixtures do not perform well in durability tests. The mixtures tested did not survive 12 cycles of freezing and thawing and wetting and drying without excessive mass and volume loss. Thus, these mixtures must be placed at depths below the freezing line in the soil profile. The results demonstrated that chemically stabilized lime sludge is able to contribute bulk volume to embankments in road construction projects.

Highway Applications for Rammed Aggregate Piers in Iowa Soils, TR-443, 2003

This report describes a study to evaluate Geopier® soil reinforcement technology in transportation construction. Three projects requiring settlement control were chosen for evaluation—an embankment foundation, a box culvert, and a bridge approach fill. For each project, construction observations, in situ soil testing, laboratory material characterization, and performance monitoring were carried out. For the embankment foundation project, Geopier elements were installed within and around an abutment footprint for the new I-35 overpass at the US Highway 5/Interstate 35 interchange in Des Moines, Iowa. Although the main focus of this investigation was to evaluate embankment foundation reinforcement using Geopier elements, a stone column reinforced soil provided an opportunity to compare systems. In situ testing included cone penetration tests (CPTs), pressuremeter tests (PMTs), Ko stepped blade tests, and borehole shear tests (BSTs), as well as laboratory material testing. Comparative stiffness and densities of Geopier elements and stone columns were evaluated based on full-scale modulus load tests and standard penetration tests. Vibrating wire settlement cells and total stress cells were installed to monitor settlement and stress concentration on the reinforcing elements and matrix soil. Settlement plates were also monitored by conventional optical survey methods. Results show that the Geopier system and the stone columns performed their intended functions. The second project involved settlement monitoring of a 4.2 m wide x 3.6 m high x 50 m long box culvert constructed beneath a bridge on Iowa Highway 191 south of Neola, Iowa. Geopier elements were installed to reduce total and differential settlement while ensuring the stability of the existing bridge pier foundations. Benefits of the box culvert and embankment fill included (1) ease of future roadway expansion and (2) continual service of the roadway throughout construction. Site investigations consisted of in situ testing including CPTs, PMTs, BSTs, and dilatometer tests. Consolidated drained triaxial compression tests, unconsolidated undrained triaxial compression test, oedometer tests, and Atterberg limit tests were conducted to define strength and consolidation parameters and soil index properties for classification. Vibrating wire settlement cells, total stress cells, and piezometers were installed for continuous monitoring during and after box culvert construction and fill placement. This project was successful at controlling settlement of the box culvert and preventing downdrag of the bridge foundations, but could have been enhanced by reducing the length of Geopier elements at the ends of the box culvert. This would have increased localized settlement while reducing overall differential settlement. The third project involved settlement monitoring of bridge approach fill sections reinforced with Geopier elements. Thirty Geopier elements, spaced 1.8 m apart in six rows of varying length, were installed on both sides of a new bridge on US Highway 18/218 near Charles City, Iowa. Based on the results of this project, it was determined that future applications of Geopier soil reinforcement should consider extending the elements deeper into the embankment foundation fill, not just the fill itself.

Iowa Department of Administrative Services Central Procurement Enterprise (CPE) Policy and Procedures Manual, December 2013

Report on a review of the Central Procurement Enterprise (CPE) of the Iowa Department of Administrative Services for the period July 1, 2009 through March 31, 2013

Endeavors Update, Iowa Medicaid Enterprise, April 2013

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, December 2012

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, December 2013

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, February 2013

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, February 2014

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, January 2013

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, January 2014

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, July 2013

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, June 2013

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, March 2014

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, May 2013

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.

Endeavors Update, Iowa Medicaid Enterprise, November 2012

The Iowa Medicaid Enterprise (IME) is an endeavor, started in 2005, to unite State staff with “best of breed” contractors into a performance-based model for administration of the Medicaid program.