Erosion and Sediment Control at Whipple Dam State Park
Whipple Dam State Park is a 256-acre State Park located in Huntingdon County, Pennsylvania. A significant increase in rainfall has caused portions of the park to suffer damage from sheet erosion. To mitigate erosion at Whipple Dam State Park, an erosion and sediment control plan must be established. The plan will address sand eroding on multiple sections of the beach, a sink hole on the beach, and a section of the parking lot that is washed out. The beach erosion will be resolved by transforming a grassed-area located between the parking lot and the beach into a grassed waterway. The grassed waterway will serve as a preventative to the movement of sheet flow from the parking lot to the beach by guiding the runoff into a nearby stormwater inlet. The main staircase to the beach acts as a conveyance for stormwater, which is causing sand below the staircase to wash out, leaving a substantial gap between the bottom step and the beach. The staircase will be removed and redesigned to redirect stormwater runoff. The sink hole will be treated accordingly based on the cause, which is in the process of being determined. From information gathered thus far, the sink hole is most likely the result of groundwater from underground water pipes. If this is true, the pipes will have to be dug up, and either replaced or repaired. The parking lot erosion will be mitigated by altering an adjacent poorly-draining ditch to become a vegetated bioswale. The vegetated bioswale will reduce erosion drastically by redirecting the stormwater to a nearby drain while gathering sediment from the runoff. Rain gardens will be place in the path of runoff in areas consisting of predominantly soil and mulch to capture the runoff moving towards the beach. Special care will be taken when creating the rain garden to ensure only plants native to the park will be planted. Existing runoff flowrates will be achieved using data collected from a Trimble Geo 7x, which will be converted into a shapefile/s and uploaded to ArcGIS. From there, the ArcGIS data will be input to Hydrology Studio, which will provide the runoff values. After the flowrates are determined, the grassed waterway, stairs specifications, and the vegetated bioswale, and the rain gardens will be quantified. Runoff calculations for the park including the grassed waterway, new staircase, vegetated bioswale, and rain gardens will be performed to confirm the proposed design will be effective in mitigating erosion at Whipple Dam State Park.