Stormwater and Stream Enhancement Plan for Winkler, Hodges, and Boone Creeks PROJECT PURPOSE The purpose of the project is to improve the hydrologic conditions in and around the area of the Boone Mall by reducing sediment and pollutant loading, mitigate flooding/reduce flooding frequency, and improving stormwater management. The project scope includes approximately ±2600 linear feet along Winkler Creek, ±1500 linear feet along Hodges Creek, and ±1200 linear feet along Boone (Kraut) Creek (see Town of Boone Conceptual Plan map). PROJECT NEED The Boone Mall and the surrounding urban area experience severe flooding during heavy precipitation events due to the impact of increased residential and commercial development, along with antiquated and failing stormwater management systems. All three streams (Winkler, Hodges, and Boone) are currently in a degrading state; with failing stream banks and increased collection of sediment and stormwater contaminants. Sediment accumulation (aggradation) raises the stream bed, resultaing in an increase in flooding and a decrease in biological habitats. In addition, stormwater runoff contains pollutants which are detrimental to the environment. The streambanks have poor habitat diversity, extensive invasive plants, and are severely eroded. The floodplain is largely non-existent, forcing the streams out of their banks, and onto impervious surfaces (i.e., parking lots) with largely outdated drainage mechanisms. Surrounding commercial and residential owners continually deal with clean-up and repairs from flood waters, an expensive and ongoing maintenance. There are innovative approaches and technologies which can be applied to the area which will greatly improve function, appearance, cost, and environmental health of the surrounding landscape. Innovative, green stormwater infrastructure should be implemented in these areas to provide a mechanism for filtration and dissipation of stormwaters. The Existing landscaping is outdated and could use modernizing with a green-development approach which will improve the aesthetics of the mall while integrating stormwater best management practices (BMPs). STREAMS/SITE LOCATION The project site location, in and around the Boone Mall, includes: Hodges Creek flowing northwest to southeast toward the mall, Boone Creek flowing from north to southeast of the mall, and Winkler Creek flowing from northeast to southeast, south of the mall. In addition, there are multiple stormwater outfalls surrounding the mall parking lot, as well as other businesses, and other impervious surfaces along the streams. PROJECT PARTNERS Partners for the proposed project include New River Conservancy and Town of Boone as project leads, in addition to individual landowners. There are approximately 25 different landowners along the project reach. DEFINITIONS Riparian Zone - A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by hydrophilic plants. Stormwater Runoff - Stormwater runoff is rainfall that flows over the ground surface. It is created when rain falls on roads, driveways, parking lots, rooftops and other paved surfaces that do not allow water to soak into the ground. Stormwater runoff is the number one cause of stream impairment in urban areas. Percolate - (of a liquid) filter gradually through a porous surface or substance. Aggrading (Sediment) - Aggradation (or alluviation) is the term used in geology for the increase in land elevation, typically in a river system, due to the deposition of sediment. Aggradation occurs in areas in which the supply of sediment is greater than the amount of material that the system can transport. Degrading - In geology, degradation refers to the lowering of a fluvial surface, such as a stream bed or floodplain, through erosional processes. BEHI - The Bank Erosion Hazard Index (BEHI), created by Dave Rosgen of Wildland Hydrology, Inc., assigns point values to several aspects of bank condition and provides an overall score that can be used to inventory stream bank condition over large areas, prioritize eroding banks for remedial actions, etc. Bankfull - The Bankfull stage of is the height of water in a natural channel at its maximum height before flooding. If the water level exceeds the bankfull limit, then a flood will occur. Channel (Floodplain, n.d.) Floodplain - A floodplain or flood plain or flood-plain is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge. RSC - Regenerative Stormwater Conveyance (RSC) is an innovative approach to provide stormwater treatment, infiltration, and conveyance within one system. It has been used as an ecosystem restoration practice for eroded or degraded outfalls and drainage channels. Rain Garden - A rain garden is a depressed area in the landscape that collects rain water from a roof, driveway or street and allows it to soak into the ground. Planted with grasses and flowering perennials, rain gardens can be a cost effective and beautiful way to reduce runoff from your property. Stormwater Wetland - Constructed stormwater wetlands are wetland systems designed to maximize the removal of pollutants from stormwater runoff through settling and both uptake and filtering by vegetation. Detention Basin - A detention basin or retarding basin is an excavated area installed on, or adjacent to, tributaries of rivers, streams, lakes, or bays to protect against flooding and, in some cases, downstream erosion by storing water for a limited period of time. Retention Basin - A retention basin, sometimes called a wet pond, wet detention basin or stormwater management pond (SWMP), is an artificial pond with vegetation around the perimeter, and includes a permanent pool of water in its design. A retention pond looks like a regular pond but plays an important role in controlling stormwater runoff. Bioswale - Bioswales are channels designed to concentrate and convey stormwater runoff while removing debris and pollution. Bioswales can also be beneficial in recharging groundwater. Bioswales are typically vegetated, mulched, or xeriscape. They consist of a swaled drainage course with gently sloped sides (less than 6%). Examples of bioswales include RSCs, grassed, vegetated, etc. Benthic Macroinvertebrates - Benthic (meaning “bottom-dwelling”) macroinvertebrates are small aquatic animals and the aquatic larval stages of insects. They include dragonfly and stonefly larvae, snails, worms, and beetles. They lack a backbone, are visible without the aid of a microscope and are found in and around water bodies during some period of their lives. Benthic macroinvertebrates are often found attached to rocks, vegetation, logs and sticks or burrowed into the bottom sand and sediments. Benthic macroinvertebrates are commonly used as indicators of the biological condition of waterbodies. Pollutant Load - Load is the amount (mass) of a pollutant that is discharged into a water body during a period of time (i.e., tons of sediment per year). SITE SPECIFICS Site 1 Site number 1 is located along Hodges Creek near the intersection of Hwy 105 and Wilson Drive (81°40’21”W, 36°12’10”N), see Site 1 Map attached. Currently, much of the reach is fully vegetated, with the exception of some areas on the right bank upstream below 105. The reach exhibits poor bedload transport (aggradation) and severe bank erosion. Invasive plant species at this site include multiflora rose, Japanese knotweed, reed canary grass, oriental bittersweet, and virgin’s bower. There are remnants of a previous restoration attempt evident by large boulders lining the channel toe upstream. Because the installation was done improperly, the “structure” is only exacerbating the erosion as water cuts behind the rocks into the bank. Proposed conditions would include benching to improve floodplain connection, and in-stream structures for grade control, bank stability, bedload transport, and bedform diversity/habitat. Stormwater infrastructure (rain gardens and/or stormwater retention areas) would be integrated into the existing topography which would also help to alleviate flooding pressure downstream. Invasive plant species would be removed and replaced with native plant species and livestakes. There is one section within Site 1 that will only allow for livetaking, just east of the Wilson Drive bridge. Site Constraints include several existing culverts entering the stream at this location, Highway 105, Wilson Drive, and parking lots are in the immediate surroundings, and existing utilities such as waterline or sewer crossing, and power poles. Two landowners own property along this reach: ASU Endowment Fund, Skyline Membership Corporation, and Boone Land Properties LLC. Site 2 Site number 2 is located along Hodges Creek, northwest of the mall parking lot, and east of Winklers Creek Road (81°40’8”W, 36°12’10”N), see Site 2 Map attached. There is some forest along the banks of this reach, but the riparian areas are dominated by invasive species, and the entire grassed area behind the Button Rentals LLC apartment building is currently only planted with herbaceous grasses which do not assist with bank stability. Currently this reach is experiencing bank erosion and an influx of concentrated flow from stormwater outfalls draining the