of protective structures required. They 

 should be placed in well-flushed areas 

 to avoid the buildup of exhaust, petro- 

 chemicals, and other pollutants. To fa- 

 cilitate launching, it is desirable that 

 currents be minimal. Ramps have many 

 of the same placement constraints as so- 

 lid-faced revetments. The section of 

 this report on revetments should be re- 

 viewed before evaluating the environ- 

 mental compatibility of a ramp. Struc- 

 tures located around the ramp, such as 

 jetties, breakwaters and piers, should 

 be designed to prevent adverse envi- 

 ronmental impacts. 



Soc i oeconomic. Community use of 

 a ramp is encouraged over individual 

 ownership. This will help to limit the 

 number of ramps. One ramp usually 

 causes minimal adverse impacts. As the 

 number of ramps in an area increases, 

 the impacts become more intense. 



Poured concrete is probably the 

 easiest, least costly, and most popular 

 method of ramp construction. For the 

 submerged ramp section, precast slab is 

 less costly than poured concrete and 

 provides better results (Dunham and 

 Finn 1974). 



Secondary socioimpacts should be 

 considered when evaluating the environ- 

 mental compatibility of a ramp. These 

 include all the impacts associated with 

 increased human usage, such as conges- 

 tion, littering, and discharging pollu- 

 tants. 



Biological. Disturbance of wetlands 

 should be minimized. During construc- 

 tion, matting or vehicles designed to 

 prevent soil compaction should be used. 

 Extra filling of the wetlands should be 

 avoided. Turbidity control devices 

 should be used when necessary to pre- 

 vent adverse impacts on the local aqua- 

 tic community. Ramps should be con- 

 structed in areas where minimal or no 

 dredging is required. Review of the 

 section on revetments in this report 

 would help to determine the biological 

 placement constraints for ramps. 



Construction Materials 



grating, asphalt, or any other material 

 with a reasonable degree of structural 

 integrity and resistance to decay in an 

 aquatic environment. 



Expected Life S pan 



The literature did not provide the 

 specific information on the expected 

 life span of ramps. Unpaved or submerged 

 asphalt ramps generally will not last as 

 long as concrete ramps. 



Summary of Physi c al and Biological 

 I mpacts 



Construction effects . The construc- 

 tion of a ramp can cause suspension of 

 sediments causing increased turbidity, 

 reduction in productivity, smothering of 

 benthic organisms, release of toxic sub- 

 stances, and altered bottom habitat. A 

 specified area of shoreline habitat is 

 removed from the aquatic system and is 

 replaced, in most cases, by less produc- 

 tive habitat, particularly if the launch- 

 ing ramp area is used heavily. 



The use of construction equipment 

 will increase noise and air pollution. 

 However, these impacts are usually 

 slight and short in duration. Construc- 

 tion equipment can also disturb a wet- 

 land edge zone by causing soil compac- 

 tion, which can have lasting adverse 

 effects. 



Chronic effects . The greatest im- 

 pacts are usually caused by related 

 activities, such as dredging, protective 

 structures, channel deepening, parking 

 facilities, and increased human usage in 

 the area. Boats and planes cause in- 

 creased turbulence as well as petrochem- 

 ical and noise pollution which can af- 

 fect the diversity of fish and wildlife 

 inhabiting the area. Ramps can make for- 

 merly inaccessible areas accessible to 

 fishermen and sightseers. This increased 

 accessibility may result in modifica- 

 tions to existing populations of organ- 

 isms. It is also possible that the 

 areater frequency of boat wakes may 

 initiate or increase shoreline erosion 

 along the waterway, causing a need for 

 other protective structures. 



Construction materials may consist 

 of qravel, shell, wood, concrete, steel 



of 



Cumulative effects. Construction 

 a ramp will replace some intertidal 



77 



