Detention Areas Detention areas are typically excavated areas that are constructed near the down- stream side of a watershed. Detention cells provide sufficient volume to allow stormwater to collect and release at a slower rate than the incoming flow. These cells provide a valuable reduction in the peak stormwater flows discharging from a drainage area. Detention cells should be considered for new projects on campus, in the early phases of site design. Underground detention can be used in a built environment when surface space does not allow for a typical stormwater detention area, includes the use of under- ground detention. This type of detention utilizes chambers installed below grade that are connected via a series of pipes to a common discharge point. These below grade chambers can be installed underneath parking lots, permanent greenspace or other areas that will not have vertical structures built upon them in the future.
Capture and Re-Use of Stormwater Stormwater capture and re-use will reduce the quantity of stormwater runoff and provide an additional source of water for landscape irrigation. It includes the use of storage devices to collect runoff from smaller rainfall events and stores the rainwater for future uses. Storage devices normally include below-grade cisterns, above-grade rain barrels or similar devices. Stormwater capture is suited for areas with low visibility adjacent to existing buildings within campus such as residential dorms, administrative and academic buildings.
Linear Greenspace and drainage facing West from the UNK Fountain
Storm Sewer Outfalls into the Tailrace There are several storm sewer outfall locations along the length of the tailrace within the UNK campus. These storm sewer outfalls are varied in their construc- tion materials and many of these outfalls are experiencing pipe failure or erosion issues at the tailrace. To mitigate continued erosion and future maintenance costs associated with these outfalls, it is recommended that a standard detail and engineering design is developed to properly secure these pipe outfalls and pro- vide a long-term structure capable of reducing erosion. Examples of these details include: drop structures, gabion structures, grouted riprap, concrete splash pads, and rock outfall protection. The maintenance of the outfall locations is critical to the long-term performance of the structures. Regular yearly inspections and main- tenance should be performed on the outfall structures to prolong their life span and reduce future repair costs.
Underground Detention Area
Stormwater Storage Device
Green Roof Systems Green roof systems can be added to the roofs of new buildings to help moderate the interior heating and cooling demand, slow stormwater runoff, utilize rainfall for plant irrigation and create usable rooftop spaces. They are modular and are also adaptable for use on existing buildings. Green roofs provide stormwater manage- ment by capturing rainfall in the growing medium of the roof system. This rainfall is used by the plants, evaporates from the soil and excess water discharges to the roof’s downspout system.
Guidelines for Existing Storm Sewer Infrastructure The campus environment has an extensive network of existing storm sewer pipes, inlets and outlets. In addition to the application of the stormwater Best Manage- ment Practices listed above, there are improvements that can be made to the exist- ing infrastructure that can assist the goals of the landscape master plan. Linear Greenspace Areas There are a handful of locations on campus, which feature linear greenspace areas between two parallel sidewalks. Specific examples of these locations include the landscape areas to the north and east of the UNK Fountain. The north greenspace area is sunken below the elevation of the sidewalk and includes stormwater inlets placed in the low elevations, which is an efficient method of collecting stormwater drainage. One goal of the landscape master plan is to reconfigure these green- space areas so that they are more attractive and more suitable for use by students. Recommended improvements include installing soil material within these green- space areas to bring the elevation above the sidewalk grades. Improvements to the storm sewer would be necessary to accomplish this goal because of the change in drainage patterns. The storm sewer inlets could be moved from the middle of the greenspace areas, and be placed at the perimeter to pick up drainage from the greenspace and sidewalk. These inlets at the sidewalk should have a standard detail and construction that will provide efficient drainage, easy maintenance, and a consistent look throughout campus.
Tail Race Storm Sewer Outfall
Green Roof System
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Chroma Design Inc.
University of Nebraska - Kearney Campus Landscape Master Plan
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