Special Events Planning, 2010

The Iowa Department of Transportation (Iowa DOT) Special Events Planning (SEP) document is a collection of Special Event Management Strategic Plans for individual events throughout the state of Iowa. The development of the SEP document focused on improving travel, safety and efficiency to and from Iowa’s largest traffic generating events through the review of event specific traffic management components. Initially, three events were selected from the state of Iowa for inclusion in the SEP document. As Strategic Plans are developed for additional events, those events will be included in the SEP document. The three initial events that are included in this SEP are: • Iowa State Fair; • Iowa State University Home Football Games; • University of Iowa Home Football Games. The Strategic Plan for each event documents existing transportation conditions for the event based on field observations, highlights positive existing practices and issues for consideration, and provides recommendations, both short and long term, to be considered as potential improvements to event operations. The objective of each Strategic Plan was, at a high-level, to analyze traffic and pedestrian flow at each event and to work with event staff, agencies and others in developing roadway, operations and safety improvements where appropriate. The SEP document is intended to be a “living” document with updates to the Strategic Plans occurring as warranted and additional Strategic Plans being incorporated for other events. The enacting of recommendations contained within each Strategic Plan is not a mandate for the responsible agency for a particular event. The Strategic Plans are intended to provide a basis for discussion between the Iowa DOT and agencies involved in the planning and implementation of transportation operations for large traffic events regarding opportunities to improve the event patron’s experience.

Use of LIDAR-based Elevation Data for Highway Drainage Analysis: A Qualitative Assessment, 2003

US Geological Survey (USGS) based elevation data are the most commonly used data source for highway hydraulic analysis; however, due to the vertical accuracy of USGS-based elevation data, USGS data may be too “coarse” to adequately describe surface profiles of watershed areas or drainage patterns. Additionally hydraulic design requires delineation of much smaller drainage areas (watersheds) than other hydrologic applications, such as environmental, ecological, and water resource management. This research study investigated whether higher resolution LIDAR based surface models would provide better delineation of watersheds and drainage patterns as compared to surface models created from standard USGS-based elevation data. Differences in runoff values were the metric used to compare the data sets. The two data sets were compared for a pilot study area along the Iowa 1 corridor between Iowa City and Mount Vernon. Given the limited breadth of the analysis corridor, areas of particular emphasis were the location of drainage area boundaries and flow patterns parallel to and intersecting the road cross section. Traditional highway hydrology does not appear to be significantly impacted, or benefited, by the increased terrain detail that LIDAR provided for the study area. In fact, hydrologic outputs, such as streams and watersheds, may be too sensitive to the increased horizontal resolution and/or errors in the data set. However, a true comparison of LIDAR and USGS-based data sets of equal size and encompassing entire drainage areas could not be performed in this study. Differences may also result in areas with much steeper slopes or significant changes in terrain. LIDAR may provide possibly valuable detail in areas of modified terrain, such as roads. Better representations of channel and terrain detail in the vicinity of the roadway may be useful in modeling problem drainage areas and evaluating structural surety during and after significant storm events. Furthermore, LIDAR may be used to verify the intended/expected drainage patterns at newly constructed highways. LIDAR will likely provide the greatest benefit for highway projects in flood plains and areas with relatively flat terrain where slight changes in terrain may have a significant impact on drainage patterns.

1113-005 Duck Creek Wateshed Final Report

The Duck Creek watershed has been the target study area of multiple reports by multiple agencies including a 2009 DNR Watershed Master Planning Grant, and the 2011 Duck and Blackhawk Creek Stream Assessment. The information obtained from these reports has lead the City of Davenport to take a micro-watershed approach to identifying the significant contributors to flooding and water quality issues that affect Duck Creek, its tributaries and the surrounding landscape, and devise solutions to mitigate these concerns. The construction of the proposed Littig Area Detention Basin comes as a recommendation from the Comprehensive Stormwater Management Plan for Pheasant, Goose, and Silver Creeks as prepared by James M. Montgomery, Consulting Engineers, Inc. in September 1991. At the time this report was prepared this basin was one of eight regional detention basins proposed in the upstream watersheds to alleviate flooding on tributaries to Duck Creek. The basin is designed and situated to detain runoff from approximately two hundred and twenty-seven (227) acres of previously developed moderate density residential area with intermixed light business and schools. This basin will reduce flow rates entering the receiving waters from the two, five and ten year storm events by an average of eighty-five percent (85%) and reduce flow rates from the twenty-five, fifty, and one hundred year events by a11 average of fifty percent (50%). With this flow rate reduction it is anticipated that streambank erosion in the immediate downstream receiving waters can be reduced or even stopped. The reduction in sediment leaving this upstream area will greatly enhance the water quality further downstream in Goose and Duck Creeks.

1010-005 Bloody Run Creek Watershed Final Report

The City of Marquette lies in the 65,000 acre Mississippi River watershed, and is surrounded by steep bluffs. Though scenic, controlling water runoff during storm events presents significant challenges. Flash-flooding from the local watershed has plagued the city for decades. The people of Marquette have committed to preserve the water quality of key natural resources in the area including the Bloody Run Creek and associated wetlands by undertaking projects to control the spread of debris and sediment caused by excess runoff during area storm events. Following a July 2007 storm (over 8” of rain in 24 hours) which caused unprecedented flood damage, the City retained an engineering firm to study the area and provide recommendations to eliminate or greatly reduce uncontrolled runoff into the Bloody Run Creek wetland, infrastructure damage and personal property loss. Marquette has received Iowa Great Places designation, and has demonstrated its commitment to wetland preservation with the construction of Phase I of this water quality project. The Bench Area Storm Water Management Plan prepared by the City in 2008 made a number of recommendations to mitigate flash flooding by improving storm water conveyance paths, detention, and infrastructure within the Bench area. Due to steep slopes and rocky geography, infiltration based systems, though desirable, would not be an option over surface based systems. Runoff from the 240 acre watershed comes primarily from large, steep drainage areas to the south and west, flowing to the Bench area down three hillside routes; designated as South East, South Central and South West. Completion of Phase I, which included an increased storage capacity of the upper pond, addressed the South East and South Central areas. The increased upper pond capacity will now allow Phase II to proceed. Phase II will address runoff from the South West drainage area; which engineers have estimated to produce as much water volume as the South Central and South East areas combined. Total costs for Phase I are $1.45 million, of which Marquette has invested $775,000, and IJOBS funding contributed $677,000. Phase II costs are estimated at $617,000. WIRB funding support of $200,000 would expedite project completion, lessen the long term debt impact to the community and aid in the preservation of the Bloody Run Creek and adjoining wetlands more quickly than Marquette could accomplish on its own.