Deck Grading and Drainge
No matter what size or style deck you’re building, the first step is to prepare the site. The amount of site preparation will vary from landscape to landscape and from deck to deck, but it generally includes removal of debris, trees, weeds, and structures.
Call in the pros
Although you can do finish grading and many small excavations yourself, rough grading and major excavation call for earth-moving equipment.
Even if you can do the work by hand, it may be more efficient to spend $500 to have it done all at once than to spend four weekends at hard labor. You’ll free your time to work on things you can easily do yourself.
Costs include an hourly equipment fee plus an operator expense—another reason for scheduling grading and excavation for the same time.
Official info on the topic: http://www.menlopark.org/departments/pwk/grade_guide.pdf
For ground-level or low-lying decks, you will have to install weed control. Otherwise you will have vegetation crashing your parties.
When you remove the sod, take it up in rolls and use it elsewhere in your landscape. Store it out of the sun and keep it moist if you’re not ready to use it right away.
Dry well – A dry well is a large, gravel-filled hole located at a spot lower than the deck (but above the water table) and removed from the deck site. A dry well collects water and lets it slowly disperse into the surrounding soil. It must be connected to the site by drainpipe sloped 1 inch every 4 feet. Dig a hole 3 feet deep and 2 to 4 feet wide. Fill it with coarse gravel, and cover the gravel with landscape fabric, then topsoil and sod. Landscape fabric keeps soil from washing into the gravel.
Drainage trench – A typical drainage trench is 12 inches wide and as deep as needed to maintain a slope of 1 inch per foot. Fill half of the trench with gravel, install perforated drainpipe (holes down), and add more gravel. Cover the gravel with landscape fabric, soil, and sod.
Catch basin – A catch basin is an open surface drain with a receptacle that holds water and disperses it through piping when it reaches a certain level. Install a catch basin to collect water from terrain that is too low to drain elsewhere. Concrete catch basins are sold ready to install. The drainpipe can empty into a distant dry well or—if local codes allow—into the storm sewer system.