Applied geology of the Bismarck-Mandan area, North Dakota

The Bismarck-Mandan area includes about 350 square miles located along both sides of' the Missouri River in south-central North Dakota. The area can be divided into two major physiographic divisions: the broad Missouri River floodplain and the nearly flat uplands which are dissected by minor streams. Geologic units in the area include Upper Cretaceous and lower Tertiary sandstone, siltstone, and shale and Quaternary sand, silt, clay, and gravel. Expansion of residential areas around the cities of Bismarck and Mandan results in conflicts in land-use between agricultural, urban, and resource development. This study consists of detailed geologic maps and a series of interpretive land-use maps that are intended to provide technical input for planning decisions to help resolve these conflicts. The mineral resources include moderate amounts of high-quality sand and gravel, abundant clay, and abundant riprap stone. To insure maximum use of the sand and gravel reserve, residential and industrial de.relopmet1t should not be allowed to cover the deposits. The highest quality water in the area is from the Missouri River. Ground-water can be found in large amounts in shallow Quaternary sand and gravel aquifers that follow the stream valleys. Groundwater is also present in small amounts in shallow aquifers in. the Cannonball and Tongue River Formations and in even smaller am01mts in the Hell Creek Formation. However, the quality of water taken from these bedrock aquifers is usually low. Low-quality water can be produced in large quantities from the Dakota Aquifer, at a depth of about 1000 meters. The best sources for irrigation water are the Missouri River and the sand and gravel aquifers on the Missouri River floodplain. General construction involves few problems on the flat uplands. The bearing strength is generally high and the water table is low. Scattered large granitic boulders cause some excavation problems. Areas where the shale of the Cannonball Formation has been exposed on steep slopes are often subject to slumping and soil creep. Construction problems can also be expected on the flat Missouri River valley and along the other streams. Flooding is common along all the streams except the Missouri River. Water tables are very high and many areas are poorly drained. The bearing strength of most of the materials in the lowlands is low to moderate. Safe waste disposal should be little problem on most of the flat uplands. The at least along the numerous small gullies and intermittent streams should be avoided for landfill or lagoon sites. Problems resulting from shallow water tables and flooding make the lowland areas poorly suited as waste disposal sites.