08013-009 Muchakinock Creek Final Report

The Muchakinock Creek Watershed Project began in February of 2005 to treat upland soil erosion in the creek that has lead to a 303(d) impairment. The Mahaska SWCD is currently administering this cost-share program to promote terraces, basins, and grade stabilization structures. The District is seeking funding from WIRB to treat specific abandoned mine lands in the Muchakinock Creek Watershed. These areas contribute sediment to the creek at levels second only to agricultural lands as well as acid mine drainage from open pits mines that have been left to decay across the county. The WIRB funding would be used to compliment Federal Abandoned Mine Land (AML) funding in the reclamation of these areas.

05024-009 Muchakinock Creek Watershed Final Report

The Muchakinock Creek Watershed Project began in February of 2005 to treat upland soil erosion in the creek that has lead to a 303(d) impairment. The Mahaska SWCD is currently administering this cost-share program to promote terraces, basins and grade stabilization structures. The District is now seeking funding from WIRB to treat specific abandoned mine lands in the Muchakinock Creek Watershed. These areas contribute sediment to the creek at levels second only to agricultural lands as well as acid mine drainage from open pits mines that have been left to decay across the county. The WIRB funding would be used to compliment Federal Abandoned Mine Land (AML) funding in the reclamation of these areas.

Green Bay Levee and Drainage District Public Assistance Grants, June 30, 2003

Other Audit Reports

Development of the Iowa Drainage Law Manual, March 2005

Although Iowa has some of the most productive agricultural land in the nation, it also maintains a very extensive road network.Consequently, landowners and roadway officials often must deal with drainage issues affecting private lands and public highways. However, many individuals are unfamiliar with legal drainage requirements, practices, and procedures, which can result in misunderstandings concerning maintenance responsibilities for drainage facilities, sometimes leading to litigation. To assist propertyowners, public agencies, and others with interest in better understanding drainage maintenance responsibilities, a reference manual was developed to describe Iowa’s drainage laws and offer interpretations in a clear and concise manner. To develop a comprehensive drainage manual, researchers identified and reviewed current available literature. These resources described pertinent drainage issues and presented explanations of legal responsibilities. The literature review included manuals and guides from Iowa, surrounding states, and federal agencies. Researchers developed a survey to assess the needs and interestsof potential users of an Iowa drainage law manual. Survey responses were used to identify common problems and concerns among individuals who encounter drainage issues on a regular basis. Issues mentioned in the survey responses included interpretation of drainage laws and commonly encountered questions relating to public improvements and private interests. Many individuals, including county engineers, stated interest in specific topics such as maintenance and/or diversion of drainage, landowner issues, and upstream and downstream impacts. Overall, the survey provided researchers with valuable information regarding drainage issues, problems, current policies, and concerns. A comprehensive manual of Iowa drainage law will assist agencies and individuals in interpreting current code requirements and in implementing effective and beneficial solutions when dealing with drainage issues.

Audit report on the Disaster Grants – Public Assistance program of the Green Bay Levee and Drainage District in Lee County, Iowa for the year ended June 30, 2009

Audit report on the Disaster Grants – Public Assistance program of the Green Bay Levee and Drainage District in Lee County, Iowa for the year ended June 30, 2009

Audit report on the Disaster Grants – Public Assistance program of Louisa – Des Moines County Drainage District in Des Moines County and Louisa County, Iowa for the year ended June 30, 2009

Audit report on the Disaster Grants – Public Assistance program of Louisa – Des Moines County Drainage District in Des Moines County and Louisa County, Iowa for the year ended June 30, 2009

Audit report on the Disaster Grants – Public Assistance program of Louisa – Des Moines County Drainage District #4 in Des Moines County and Louisa County, Iowa for the year ended June 30, 2010

Audit report on the Disaster Grants – Public Assistance program of Louisa – Des Moines County Drainage District #4 in Des Moines County and Louisa County, Iowa for the year ended June 30, 2010

Drainage Basins of Iowa, March 1, 2000

Map of Drainage Basins of Iowa produced by the Iowa Department of Transportation.

Drainage Basins of Iowa, September 1, 2008

Map of Drainage Basins of Iowa produced by the Iowa Department of Transportation.

Drainage Basins of Iowa, March 1, 2000

Map of Drainage Basins of Iowa produced by the Iowa Department of Transportation.

Audit report on the Missouri Valley Drainage District for the year ended June 30, 2012

Audit report on the Missouri Valley Drainage District for the year ended June 30, 2012

Evaluating Roadway Subsurface Drainage Practices, 2013

The bearing capacity and service life of a pavement is affected adversely by the presence of undrained water in the pavement layers. In cold winter climates like in Iowa, this problem is magnified further by the risk of frost damage when water is present. Therefore, well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (DOT). However, controversial findings are also reported in the literature regarding the benefits of subsurface drainage. The goal of this research was not to investigate whether subdrains are needed in Iowa pavements, but to conduct an extensive performance review of primary interstate pavement subdrains in Iowa, determine the cause of the problem if there are drains that are not functioning properly, and investigate the effect of poor subdrain performance due to improper design, construction, and maintenance on pavement surface distresses, if any. An extensive literature review was performed covering national-level and state-level research studies mainly focusing on the effects of subsurface drainage on performance of asphalt and concrete pavements. Several studies concerning the effects of a recycled portland cement concrete (RPCC) subbase on PCC pavement drainage systems were also reviewed. A detailed forensic test plan was developed in consultation with the project technical advisory committee (TAC) for inspecting and evaluating the Iowa pavement subdrains. Field investigations were conducted on 64 selected (jointed plain concrete pavement/JPCP and hot-mix asphalt/HMA) pavement sites during the fall season of 2012 and were mainly focused on the drainage outlet conditions. Statistical analysis was conducted on the compiled data from field investigations to further investigate the effect of drainage on pavement performance. Most Iowa subsurface drainage system outlet blockage is due to tufa, sediment, and soil. Although higher blockage rates reduce the flow rate of water inside outlet pipes, it does not always stop water flowing from inside the outlet pipe to outside the outlet pipe unless the outlet is completely blocked. Few pavement surface distresses were observed near blocked subsurface drainage outlet spots. More shoulder distresses (shoulder drop or cracking) were observed near blocked drainage outlet spots compared to open ones. Both field observations and limited performance analysis indicate that drainage outlet conditions do not have a significant effect on pavement performance. The use of RPCC subbase in PCC pavements results in tufa formation, a primary cause of drainage outlet blockage in JPCP. Several useful recommendations to potentially improve Iowa subdrain performance, which warrant detailed field investigations, were made

Evaluating Roadway Subsurface Drainage Practices: Tech Transfer Summary, 2013.

The bearing capacity and service life of a pavement is affected adversely by the presence of undrained water in the pavement layers. In cold winter climates like in Iowa, this problem is magnified further by the risk of frost damage when water is present. Therefore, well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (DOT). However, controversial findings are also reported in the literature regarding the benefits of subsurface drainage. The goal of this research was not to investigate whether subdrains are needed in Iowa pavements, but to conduct an extensive performance review of primary interstate pavement subdrains in Iowa, determine the cause of the problem if there are drains that are not functioning properly, and investigate the effect of poor subdrain performance due to improper design, construction, and maintenance on pavement surface distresses, if any. An extensive literature review was performed covering national-level and state-level research studies mainly focusing on the effects of subsurface drainage on performance of asphalt and concrete pavements. Several studies concerning the effects of a recycled portland cement concrete (RPCC) subbase on PCC pavement drainage systems were also reviewed. A detailed forensic test plan was developed in consultation with the project technical advisory committee (TAC) for inspecting and evaluating the Iowa pavement subdrains. Field investigations were conducted on 64 selected (jointed plain concrete pavement/JPCP and hot-mix asphalt/HMA) pavement sites during the fall season of 2012 and were mainly focused on the drainage outlet conditions. Statistical analysis was conducted on the compiled data from field investigations to further investigate the effect of drainage on pavement performance. Most Iowa subsurface drainage system outlet blockage is due to tufa, sediment, and soil. Although higher blockage rates reduce the flow rate of water inside outlet pipes, it does not always stop water flowing from inside the outlet pipe to outside the outlet pipe unless the outlet is completely blocked. Few pavement surface distresses were observed near blocked subsurface drainage outlet spots. More shoulder distresses (shoulder drop or cracking) were observed near blocked drainage outlet spots compared to open ones. Both field observations and limited performance analysis indicate that drainage outlet conditions do not have a significant effect on pavement performance. The use of RPCC subbase in PCC pavements results in tufa formation, a primary cause of drainage outlet blockage in JPCP. Several useful recommendations to potentially improve Iowa subdrain performance, which warrant detailed field investigations, were made.

Estimating Design-Flood Discharges for Streams in Iowa Using Drainage-Basin and Channel-Geometry Characteristics, HR-322, 1993

Drainage-basin and channel-geometry multiple-regression equations are presented for estimating design-flood discharges having recurrence intervals of 2, 5, 10, 25, 50, and 100 years at stream sites on rural, unregulated streams in Iowa. Design-flood discharge estimates determined by Pearson Type-III analyses using data collected through the 1990 water year are reported for the 188 streamflow-gaging stations used in either the drainage-basin or channel-geometry regression analyses. Ordinary least-squares multiple-regression techniques were used to identify selected drainage-basin and channel-geometry regions. Weighted least-squares multiple-regression techniques, which account for differences in the variance of flows at different gaging stations and for variable lengths in station records, were used to estimate the regression parameters. Statewide drainage-basin equations were developed from analyses of 164 streamflow-gaging stations. Drainage-basin characteristics were quantified using a geographic-information-system (GIS) procedure to process topographic maps and digital cartographic data. The significant characteristics identified for the drainage-basin equations included contributing drainage area, relative relief, drainage frequency, and 2-year, 24-hour precipitation intensity. The average standard errors of prediction for the drainage-basin equations ranged from 38.6% to 50.2%. The GIS procedure expanded the capability to quantitatively relate drainage-basin characteristics to the magnitude and frequency of floods for stream sites in Iowa and provides a flood-estimation method that is independent of hydrologic regionalization. Statewide and regional channel-geometry regression equations were developed from analyses of 157 streamflow-gaging stations. Channel-geometry characteristics were measured on site and on topographic maps. Statewide and regional channel-geometry regression equations that are dependent on whether a stream has been channelized were developed on the basis of bankfull and active-channel characteristics. The significant channel-geometry characteristics identified for the statewide and regional regression equations included bankfull width and bankfull depth for natural channels unaffected by channelization, and active-channel width for stabilized channels affected by channelization. The average standard errors of prediction ranged from 41.0% to 68.4% for the statewide channel-geometry equations and from 30.3% to 70.0% for the regional channel-geometry equations. Procedures provided for applying the drainage-basin and channel-geometry regression equations depend on whether the design-flood discharge estimate is for a site on an ungaged stream, an ungaged site on a gaged stream, or a gaged site. When both a drainage-basin and a channel-geometry regression-equation estimate are available for a stream site, a procedure is presented for determining a weighted average of the two flood estimates.

Video Evaluation of Highway Drainage Systems, HR-317, 1991

Since 1978 the concept of longitudinal edge drains along Iowa primary and Interstate highways has been accepted as a cost-effective way of prolonging pavement life. Edge-drain installations have increased over the years, reaching a total of nearly 3,000 mi by 1989. With so many miles of edge drain installed, the development of a system for inspection and evaluation of the drains became essential. Equipment was purchased to evaluate 4-in.-diameter and geocomposite edge drains. Initial evaluations at various sites supported the need for a postconstruction inspection program to ensure that edge-drain installations were in accord with plans and specifications. Information disclosed by video inspections in edge drains and in culverts was compiled on videotape to be used as an informative tool for personnel in the design, construction, and maintenance departments. Video evaluations have influenced changes in maintenance, design, and construction inspection for highway drainage systems in Iowa.