Entire Document - California Department of Boating and Waterways ...

If a particular type of dock cannot be designed for a 25#/ft 2 ULL and functionproperly under expected site conditions, then it is not the type of dock that shouldbe provided at that site. The solution may lie with operational procedures such asseasonal closures of a marina, or removal of docks from the water because ofseasonal flooding, storms, ice, etc.......................................................................C2.2.2 Snow and Ice LoadsCommentary:Snow and ice zones are not limitedsolely to higher elevation lakes andreservoirs. The two-week period ofsustained sub-freezing weather thatoccurred in Central California in 1990 didmore damage to public and privateproperty than the 1989 Loma Prietaearthquake. Insurance claims related tofreezing damage exceeded those fromthe earthquake.Heavy Snow Burden on Boats & DocksIf snow and ice are not removed frommarina docks, a continued buildup can gradually increase the load and reduce thefreeboard to unacceptable levels. Utilities may become submerged and structuralconnections may be stressed beyond design limits. Also, snow and ice on mooredboats may impart heavy loads to the docks, and boat lines, intended to tie a boat tothe dock, may pull a dock under water if the boat(s) is overburdened and begins tosink.Marina decks should be designed, built and maintained such that snow and ice meltdrains off the decks. Decks sometimes slightly curl, creating shallow basins thathold snow melt. Such ponded water may freeze overnight and create a “black ice”safety problem for both marina staff and boaters. Practical ways of addressing thisproblem include provision of drain holes in the deck, or using decking with openingssuch as 2x6s with ½ inch gaps betweendecking planks. Vinyl bumper materialalong the edge of a dock can also act asa shallow dam causing water to pond onthe deck. Leaving ½" gaps between theends of the vinyl strips will allow some ofthe snow melt to drain away. Care mustbe taken to insure that runoff does notdrain into the flotation pontoons. Thiscan sometimes be a problem on olderdocks with polyethylene pontoons fittedwith plywood lids.Serious Houseboat and Dock Snow JobAppendix A -- Section C Commentary - Page 72