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32 <br /> schnabel-eng.com 2. Project References / Lake Orange Intake Tower / 16 <br /> Durant Nature Park Lower Dam Repairs S. Kees served s <br /> RALEIGH, NC as PM & FOR Z = <br /> _. --- - - <br /> .t <br /> �±'.y� it ., _:1`rx; _:�•._... _`•'S�•.'.^;r:-s;.:�. .. <br /> SERVICES The Durant Nature Park Lower Dam is a 25-foot-high earthen <br /> Alternatives Analysis embankment dam. The dam was originally classified as a small- <br /> Control of Water Design size, low hazard structure by NC Dam Safety. Three dam safety <br /> Construction Observation related issues were identified during a visual inspection of the <br /> Dam Inspection dam performed by Schnabel in 2013. These included erosion, <br /> Dive Inspection scour, and slab undermining at the chute spillway outlet due to <br /> erosion of a riprap basin; the unknown condition and operability <br /> Emergency Action Plan of the low-level outlet; and the observed steepness of the <br /> Geotechnical Analysis upstream slope of the earth embankment. Schnabel evaluated <br /> Inundation Mapping alternatives to replace the eroded riprap basin, prepared a <br /> Permitting conceptual design of a concrete energy dissipation structure, <br /> Rehabilitation Design subcontracted with a diver to inspect the low-level outlet <br /> Structural Analysis structure and operate the valve, and performed slope stability <br /> analyses of the upstream slope using embankment geometries <br /> OWNER/CLIENT gathered during the dive inspection. <br /> City of Raleigh The energy dissipation structure was designed as a Straight <br /> Gilles Bellot, PE Drop Spillway Stilling Basin to reduce the volume of earthwork <br /> P: 919.996.4001 and rock excavation required. The drop structure was <br /> E: gilles.bellot@raleighnc.gov constructed in the reshaped scour hole that developed after <br /> the original plunge pool eroded. Schnabel performed all of the <br /> hydrology and hydraulic, geotechnical, and structural analyses <br /> and designs for the slope improvements and stilling basin design. We also provided bid support <br /> and construction phase services consisting of submittal review and construction inspection during <br /> key portions of construction. <br /> With updated inundation mapping, the dam was identified as now being High Hazard based on <br /> NC Dam Safety regulations due to development downstream of the dam. Schnabel prepared the <br /> Emergency Action Plan, Inundation Maps, and Operation and Maintenance Manual for the dam to <br /> meet the requirements of a High Hazard structure. Construction was completed in 2019. <br /> Build Better.Together. <br />