寒武系-奥陶系基岩含水层系统位于美国中西部上部161000平方英里的下方。含水层广泛用于市政供水，油井产量通常为每分钟750至1500加仑。该含水层的水质通常非常坚硬，在其大部分范围内为淡水至微咸水。大部分含水层受Maquoketa页岩的限制，如果受到限制，通常会超过组合镭、总α和/或氡的最大污染水平（MCL）。在某些地区，水也可能超过氟化物、钡、砷、总溶解固体、铁和硫酸盐饮用水标准。 由于水质问题和含水层的过度使用，许多公用事业公司放弃了基岩井供水，转而使用其他浅层地下水或地表水水源。然而，许多公用事业公司维护基岩井，以备紧急或备用。威斯康星州Oak Creek的Oak Creek水和下水道公用设施（OCWSU）就是这样一个公用设施。威斯康星州南部的密尔沃基郊区社区。1976年之前，OCWSU使用从穿透寒武-奥陶系砂岩含水层的深井供应的地下水为其客户提供饮用水。1976年，他们开始使用每天600万加仑的密歇根湖水处理厂，并将三口砂岩含水层水井置于紧急备用状态。 由于郊区的增长，OCWSU已经开始了一项昂贵的扩建计划，其中包括两个阶段的水处理厂扩建，以满足未来20年的预计需求。在1997，OWSU开始考虑将其备用威尔斯转换为含水层存储和恢复（ASR）威尔斯作为第二阶段的水处理厂扩建的潜在替代物。如果可行，ASR将使扩建水处理厂的建设和运营每年节省50%的成本。然而，与寒武系-奥陶系含水层中的许多其他井一样，备用井产生的水超过了混合镭的主要饮用水标准，以及其他几个二级标准。 在1998，OWWSU从AWWA研究基金会（项目2539）获得了定制的合作资金，进行了一个示范性试验计划，以确定在威斯康星寒武系奥陶系含水层中使用ASR的可行性及其对原生地下水中组合镭的影响。在12个月的时间内进行了四次蓄水和恢复循环，以确定原生地下水水质和含水层矿物学对蓄水水质的影响。收集再充水和回收水的样本，并分析其镭、氡、总α、三卤甲烷和其他无机参数。 在第一次全尺寸试验循环中，100%的水在镭放射性水平低于饮用水标准的情况下被回收。目前超过联合镭标准的其他公用事业现在可以考虑ASR作为建设处理设施的一种可能的成本效益的替代方案。包括数字。

The Cambrian-Ordovician bedrock aquifer system underlies 161,000 square miles of the upper midwestern United States. The aquifer is widely used for municipal water supply and well yields are typically 750 to 1,500 gallons per minute. The water quality of this aquifer is generally very hard and fresh to slightly brackish throughout most of its extent. The majority of the aquifer is confined by the Maquoketa shale and where confined, often exceeds the maximum contaminant level (MCL) for combined radium, gross alpha, and/or radon. In some areas the water may also exceed the fluoride, barium, arsenic, total dissolved solids, iron, and sulfate drinking water standards. Due to water quality issues and overuse of the aquifer, many utilities have abandoned their bedrock well supply for other sources of shallow groundwater or surface water supplies. Many utilities maintain the bedrock wells, however, for emergency or standby supply. The Oak Creek Water and Sewer Utility (OCWSU) of Oak Creek, Wisconsin is one such utility. OCWSU serves a growing suburban community south of Milwaukee, Wisconsin. Prior to 1976, OCWSU supplied its customers with potable water using groundwater supplied from deep wells penetrating the Cambrian-Ordovician Sandstone Aquifer. In 1976, they began using a 6-million gallon-per-day Lake Michigan water treatment plant and placed their three Sandstone Aquifer wells on emergency standby status. Due to suburban growth, the OCWSU has embarked on an expensive expansion program that includes two phases of water treatment plant expansion to meet projected demands over the next 20 years. In 1997, OCWSU began to consider converting their standby wells to Aquifer Storage and Recovery (ASR) wells as a potential alternative to the second phase of water treatment plant expansion. If feasible, ASR would result in a 50 percent annual cost saving over construction and operation of an expanded water treatment plant. However, like many other wells in the Cambrian-Ordovician aquifer, the standby wells produce water that exceeds the primary drinking water standard for combined radium, as well as several other secondary standards. In 1998, the OCWSU received tailored collaboration funding from the AWWA Research Foundation (Project 2539) to conduct a demonstration test program to determine the feasibility of using ASR within the Cambrian-Ordovician aquifer in Wisconsin and its affect on combined radium present in the native groundwater. Four storage and recovery cycles were performed over a 12-month period to determine the influence of the native groundwater quality and aquifer mineralogy on stored water quality. Samples of the recharged and recovered water were collected and analyzed for radium, radon, gross alpha, trihalomethanes, and other inorganic parameters. One hundred percent of the water was recovered with radium activity levels below drinking water standards from the first full-scale test cycle. Other utilities that currently exceed the combined radium standard can now consider ASR as a possible cost-effective alternative to constructing treatment facilities. Includes figures.