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o Ensure appropriate plant maintenance is occurring . <br /> o A one -time fertilizer application to establish ground cover is permissible if <br /> a soil test indicates it is necessary . No portion of the dry detention system <br /> shall be fertilized after the initial fertilization that is required to establish <br /> the vegetation . <br /> o Consult with the Town of Chapel Hill Stormwater Management Division <br /> before any aquatic herbicide is used and site specific approval is given . <br /> • If vegetation coverage is not achieved , add reinforcement planting to maintain <br /> desired vegetation density and /or split out perennials to increase plant cover . <br /> Desired vegetation coverage is 50% after 2 growing seasons and 75 % after 5 <br /> growing seasons <br /> • Remediate bare soils or erosive gullies . <br /> il to remove the gully, plant a ground <br /> o In perimeter areas , regrade the so <br /> cover and water until it is established . If soil test shows that the pH has <br /> dropped , dolomitic lime shall be applied as recommended . <br /> o Within the pretreatment area , provide erosion control devices such as <br /> reinforced turf matting or riprap to avoid future problems with erosion . <br /> Filter Media Failure <br /> • If the bioretention area shows signs of clogging, identify source of sediment and <br /> work to remediate or eliminate it before proceeding with the following <br /> maintenance tasks . <br /> o Flush the underdrains and capture any sediment before it enters any <br /> downstream stream or storm drain system . <br /> o Conduct one or more test pits to determine the depth of soil <br /> contamination . <br /> o Before remediating the filter bed , remove and temporary store any plants . <br /> o Remove the accumulated sediment to the point where sediment is no <br /> longer observed in the soil media plus an additional 2 inches of soil . Either <br /> replace with new media or till 2 to 3 inches of sand into the upper 8 to 12 <br /> inches of soil . <br /> o Dispose of any removed soil in an appropriate off-site location . <br /> o Replant and mulch the area of disturbance . <br /> • If soil test shows that the pH has dropped , dolomitic lime shall be applied as <br /> recommended . k <br /> • If the soil test shows that heavy metals have accumulated , the toxic soils shall be <br /> (' <br /> removed , disposed of properly, and replaced with new planting media . j <br /> I <br /> Structural Integrity <br /> • Replace or repair any cracked , separated or damaged inlet pipes , drop inlets, <br /> overflow structure, outfalls , impoundment walls or other structural elements . <br /> Functionality <br /> • If flow is bypassing the pretreatment area , regrade to route all flow to the <br /> pretreatment area . <br /> • Sediment Accumulation <br /> o Maintain stable ground cover in the drainage area . <br /> I` <br /> =NEI= <br />