Water Quality Impacts of Contaminated Sediment Removal Using Hydraulic Dredges

9876401海斯这个项目的目标是通过广泛的现场数据收集，结合美国铝业公司的Comfort/Lavaca Bay Superfund可处理性研究，研究使用传统液压刀盘挖泥机清除受污染沉积物对水质的影响。研究的具体目标是：(1)在代表其他补救地点的条件下，在常规水力刀盘疏浚作业期间，从挖泥头附近和水柱(25m至500m)收集水质数据，(2)在一系列疏浚作业条件下收集相同的数据，(3)评估与此类疏浚作业相关的水质影响的范围，(4)使用近场数据验证和改进Hayes(1998)提出的将泥沙再悬浮率与疏浚特性和操作参数关联的模型，(5)对沉积物进行柱状沉降试验，并尝试验证JE(1998)提出的远场悬浮泥沙输送模型；(6)根据疏浚作业期间收集的水质数据，通过计算远离现场的泥沙和汞的输入量，评估再污染的可能性，并将其与特定地点的实测泥沙沉降量和汞浓度进行比较。美国国家研究委员会(National Research Council)估计，美国每年从港口、港口和水道疏浚1400万至2800万立方码的污染沉积物，以维持既定的航行深度。已知在非通航区域和指定的超级基金地点存在较大数量的受污染沉积物。虽然这些沉积物中的许多可以留在原地，但当污染物进入食物链时，补救行动是必要的。然而，在清理过程中对水质影响过大的担忧阻碍了清理行动。这项研究的结果将提供更多关于清除污染沉积物作业对周围和下游水环境质量的影响的知识。

9876401 Hayes The objective of this project is to study the water quality impacts associated with removing contaminated sediments using a conventional hydraulic cutterhead dredge through extensive field data collection in conjunction with the ALCOA Point Comfort/Lavaca Bay Superfund Treatability Study. Specific objectives of the research are to: (1) gather water quality data from near the dredgehead and in the water column (25m to 500m) during conventional hydraulic cutterhead dredging operations under conditions representative of other remedial sites, (2) gather these same data under a range of dredge operating conditions, (3) evaluate the range of water quality impacts associated with this type of dredging operation, (4) use the near-field data to verify and refine the model proposed by Hayes (1998) that relates the rate of sediment resuspension to the dredge characteristics and operating parameters, (5) conduct column settling tests on the sediments and attempt to verify the far-field suspended sediment transport model proposed by Je (1998) and (6) evaluate the potential for recontamination by calculating the amount of sediment and mercury transported away from the site based upon the water quality data collected during the dredging operation and compare that to measured sediment deposition and mercury concentrations at specified locations. The National Research Council estimates that 14 to 28 million cubic yards of contaminated sediments are dredged annually from U.S. ports, harbors and waterways to maintain established navigation depths. Larger volumes of contaminated sediments are known to exist in non-navigable areas and designated superfund sites. While many of these sediments can remain in place, remedial actions are necessary where contaminants are finding their way into the food chain. However, concern over excessive water quality impacts during removal hampers cleanup actions. The results of this study will provide additional knowledge of the effects of contaminated sediments removal operations on the quality of the surrounding and downstream aquatic environments.