DAM SITE CHARACTERIZATION AND DAM DESIGN
STE. GENEVIEVE COUNTY, MISSOURI

LBG has designed and permitted what will be the 2nd tallest private dam in the State of Missouri. LBG’s client plans to construct a harbor on the Mississippi River by dredging alluvial sediments. The problem - Where do the sediments go? The answer – behind a dam constructed in a narrow hollow with a deeply incised drainage.

MAJOR DESIGN CHALLENGES

• Complex geologic and steep topographic conditions.
• Water table fluctuations due to proximity of large river and fracture flow.
• Karst Features – open bedding planes, jointing and fractures, losing surface water stream segment.
• Borrow clay for construction of variable thickness, permeability and sporadically distributed.

Prior to designing the dam, a comprehensive investigation of the site geology and hydrogeology was completed. LBG initially evaluated several potential dam sites before choosing the best based upon geology and maximization of storage capacity relative to construction cost.

DAM FEATURES

• Clay core and rock fill armor
• Height – 141 feet
• Crest length - 885 feet
• Impounded Surface Area – 25 acres
• Impounded volume – 744 acre-feet
• Water shed - 150 acres

Once selected, the site was thoroughly characterized. A detailed analysis of the geology (stratigraphic succession, structure, strike and dip, joint fracture and bedding planes) and hydrogeology (ground-water fluctuation, flow patterns, impact to adjoining property) were completed.