BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

Overall, dredging can be either a permanent or a temporary BMP that providesboth source and hydrologic control for water quality.8.9.2 DREDGING: ADVANTAGES AND DISADVANTAGESThe general advantages and disadvantages in using dredging as a shorezoneprotection BMP are as follows:Table 8-17: Advantages and Disadvantages of DredgingADVANTAGES• Can be conducted with standardizedpollution controls, i.e., institutionalizedoperational measures and containmentBMPs.• Allows the navigation of boats and vesselsthrough commercial channels.• Can be used to meet desired sedimentCleanup Levels (CULs) and/or achieveRemediation Goals (RGs) in nearshorerestoration and remediation efforts.• Dredge spoils may be used for beachreplenishment projects provided it has beentested (mandatory) for fine sedimentcontent, hydrocarbons, and Aquatic InvasiveSpecies (AIS) and approved by regulatoryagencies.DISADVANTAGES• Failure of turbidity curtains and booms mayresult in water quality degradation.• Fine particulates and organic compounds canbe re-suspended and discharged duringfuture operations and weather events.• Necessary when replacing or repairingshorezone protective structures. Thesesettings are difficult to control and containfor turbidity.• Disturbs the lake bottom, including smallerlife forms.• Improper placement of excavated materialcan impact temporary holding areas.• Requires disposal at appropriate receivingfacility.• Removing dredging material from the lakeand exporting it out of the basin is costly.• May have a difficult time meeting federal,state and regional water quality standards• Can further the spread of Aquatic InvasiveSpecies (AIS), if present, unless the speciesare removed part of an AIS managementplan for the project.8.9.3 DESIGN CONSIDERATIONS AND PLANNINGDredging generally occurs in five phases: 1) excavation, 2) lifting, 3) placement,4) transportation, and 5) disposal. Due to the enhanced regulatory nature ofdredging, management protocols for all stages of the practice must be carefullyevaluated and chosen. When considering implementing dredging as a shorezoneprotection BMP, institutional management practices, the management of thespoils, construction timing, water quality monitoring, and biologicalmonitoring must be considered and planned for. Institutional ManagementPractices are part of the facility’s established maintenance protocols and canprovide guidance for operation under difficult circumstances such as seiche,large wave effects, and high river discharge. 4747USACE, 2008, Coastal Engineering Manual - Parts I-6TRPA BMP HandbookCHAPTER 8: Shorezone Protective Structures and BMPs2012 8.9 DredgingPage 8-59