Maintain adequate buffer areas between the coastal zone and upland facilities.
Vegetated buffers can provide a natural filter to remove pollutants and sediments contained in surface water runoff. The effectiveness of any given vegetated buffer for removing pollutants and sediments is dependent upon a variety of site-specific conditions, such as slope, soil type, type of vegetation, and permeability. A vegetated buffer is typically found between an inland area (pollutant source) and an adjacent waterway. As runoff moves through the vegetated buffer, sediment and pollutants attached to sediment are filtered out as the buffer slows flow velocity, allowing sediment and pollutants to settle out. In general, the greater the width of vegetated buffer the surface runoff must travel through, the more sediment and pollutants it can remove.
Even relatively narrow vegetated buffers can remove large percentages of sediment and attached pollutants. For instance, a 15-foot vegetated buffer is able to remove, on average, 50 percent or more of the sediment and attached pollutants moving through the vegetated area (Desbonnet et al., 1994). To achieve an approximate 80 percent removal of sediment and attached pollutants, a vegetated buffer of 225 feet would be required (Desbonnet et al., 1994). These buffer widths apply to course-grained sediments and sand, while wider vegetated buffers may be required to effectively remove silt, clay, and other fine-grained sediments contained in runoff water. The following table summarizes pollutant removal effectiveness and wildlife habitat value of vegetated buffers according to buffer width, adapted from Desbonnet, A. et al.
Vegetated buffers that are implemented with a primary purpose of removing sediments and attached pollutants will require maintenance on a regular basis. The frequency of maintenance procedures will depend upon the amount of sediment being removed by the vegetated buffer. The majority of sediments and coarse-grained materials is removed at the leading edge of the vegetated buffer. Over time, the vegetated buffer may become "clogged" with sediment removed from runoff water, oftentimes forming a berm at its leading edge. Once a berm forms, water may be channeled around the vegetated buffer instead of through it, rendering the buffer ineffective for the treatment of surface runoff. If runoff continues to move through the vegetated buffer, the clogging action will continue to move into the buffer, reducing its effective width for treatment of runoff, and eventually rendering the vegetated buffer useless. Maintenance procedures to remove sediments will occasionally need to be conducted to keep the vegetated buffer in proper working order.
Pollutants that exist in a dissolved form in runoff water-nitrate, for instance-often require wide vegetated buffers for effective removal Dissolved pollutants are removed by uptake in plants and through both chemical and biological interactions with soils. Wider vegetated buffers are required to allow the long retention times needed for plants to utilize the pollutants, as well as to allow chemical and biological interactions to occur. Wide vegetated buffers can have multiple-use value. Although they will function to remove sediment and pollutants contained in runoff water, they can also provide habitat for wildlife, reduce erosion, and increase the aesthetic and scenic value of the area. Multiple-use value of a vegetated buffer increases as width of the buffer increases.
In order for the vegetated buffer to be effective in the removal of sediment and pollutants, it should be of shallow slope, thickly vegetated, and should be relatively level throughout its length and width. Any vegetated buffer that promotes channelized flow through its vegetated area-through gullying, for instance-will be generally ineffective for pollutant and sediment removal, will promote erosion, and will simply funnel runoff into an adjacent water body as if it were a point source of pollution.
Vegetation in the buffer will vary according to the primary purpose of its use. Thickly growing grasses that are maintained at a height of four inches or more are very effective at removing sediments and attached pollutants. Thickly growing grasses also work well to slow the velocity of runoff flow and to promote a shallow, even flow of runoff through the buffer area. Grassed buffers are also easily maintained. Interspersed shrubs, bushes, and trees in a grassed buffer area will enhance scenic and aesthetic qualities, and also promote its use by wildlife by increasing vegetative diversity.
As marinas generally rely upon direct access to the water, vegetated buffers could be implemented between inland work areas and the water's edge, leaving an access way along the actual edge of the water. The buffer could be grassed and interspersed with low-growing shrubs and bushes. This would provide sediment and attached pollutant removal from runoff water, allow for easy access and maintenance of the vegetated buffer, and provide some scenic and visual diversity within the marina. Some buffers can be used for light recreation, such as picnic areas. Areas with direct access to the water, such as boat ramps, could be engineered so that the majority of runoff they produce can be diverted into the nearby vegetated buffers rather than run down the boat ramp and directly into the water.
Implement effective rain runoff control strategies, such as surfacing areas with crushed gravel, decreasing the slope of the facility towards surface waters, or installing filters and wet ponds that remove 80 percent of total suspended solids from hull maintenance areas.
Reducing rain runoff also decreases the amount of pollution entering the water. Many techniques for achieving this exist. A less expensive approach is to cover or replace hard-packed areas that would normally allow for high runoff with a pervious material such as gravel or shell. This works especially well to slow down flow, allowing material to fall out of the moving water. Most types of marina machinery can be operated on the pervious material. Placing gravel or shell down over packed sand or dirt also helps to keep dust down and can improve the marina's aesthetics.
Another technique for reducing flow is to create a slope within the facility that does not generate a storm flow directly into the water. This could be considered at the time when other construction or infrastructure improvements are under way. Slope modification can also be achieved in conjunction with pervious material. Slope can be raised by using gravel as the filling material.
Other more complicated techniques also exist. Catch basins, either on the surface or sub-surface, can be designed and constructed to collect runoff. Once the water is collected, numerous processes can be applied to purge the water of contaminants. One method is simply to allow the material to settle out of the captured water. Other systems exist that will filtrate the water to remove contaminants. Once the pollutants are removed, the water can be released. Under current standards, the release of this water is regulated under storm water provisions of the state's environmental protection program.
Wash the boat hull above the waterline by hand. Where necessary, remove the boat from the water and perform cleaning where debris can be captured and disposed of properly.
Instead of washing the topsides of boats with a pressure washer, consider cleaning boat hulls above the waterline by hand. This practice will decrease the amount of water necessary to complete the job and will reduce the amount of potential contaminants that can enter the water. While hand washing the boats, do so in a way that minimizes the amount of debris that falls into the water. Boats should be removed from the water before cleaning or maintenance activities if the impacts of the activities cannot be contained or mitigated. For instance, if toxic chemicals are being applied during a maintenance activity and those chemicals are apt to enter the surface water, move the boat to a designated maintenance area ashore. However, if a vessel is being cleaned with nontoxic detergents, then removing the boat from the water may not be necessary.
Support the use of environmentally compatible cleaning products.
Encourage boaters to use only cleaning products that will not degrade the environment. Use low-phosphate detergents for cleaning boats and other equipment within the facility. Promote the use of biodegradable chemical counterparts to traditional chemicals commonly found on board vessels. Ensure that your ship's store has "green" products available, and help sales people understand and be able to explain the differences between traditional and environmentally compatible products.
Minimize the impacts of wastewater created during pressure washing.
During this activity, bottom growth consisting of marine organisms is washed off the hull along with particles of the bottom paint and fragments of hull material. The particles and fragments contain metals and other chemicals that retard marine growth. In concentration, such as that occurring in wastewater from pressure washing, it can have negative impact on the marine environment.
Options are available to minimize water quality degradation from pressure washing. Removal of contaminants from wastewater can be implemented in a step process, depending on the amount of pollutant removal desired or required.
- Settling-This process allows the contaminants to drop out of the wastewater once it is collected and allowed to stand, undisturbed. It requires a platform that will collect the water during the washing process and a containment facility. This method is the least expensive and easiest to design and construct. However, it is only moderately effective at removing contaminants because it will only remove particles that drop out during settling.
- Filtration-Filtration is completed by allowing the water to flow through one or more filters that screen out different sized particles. Filtration can start at the washing platform with the installation of hay bales or filtration cloth over the wash water intake drain. This method is effective for straining visible particles. Additional filtration can be achieved by directing the water through a filter or series of filters with decreasing mesh sizes.
- Treatment-This method uses existing technologies from other industries to pretreat the wastewater and remove contaminants. This method operates under the same premise as a mini-treatment plant. The treatment can include the removal of oil and grease, metals, or other contaminants, depending on the technology applied. For instance, agents can be introduced into the wastewater that encapsulate metals and force them to settle out of solution. This method is the most sophisticated level of wastewater treatment.
Once the wastewater has moved through the purification process, the marina operator must then decide to:
- discharge back into the water body;
- discharge into a sanitary system; or
- reuse for pressure washing or other applications that require water, such as irrigation.
These three options are dependent on the level of purification the water received. If the first two options are chosen, the discharge effluent will be required to meet discharge standards set for the receiving water body or sewage treatment facility. Either option will require discharge permits and water quality monitoring. The final option, reuse, may be the most appropriate practice. Reuse not only bypasses the need for discharge permits; it also achieves the goal of water conservation.
