Scope of Work
Per the general recommendations of structural engineer we will construct a drainage system along the left and rear sides of the garage. The system will start in the sub-area directly behind the right rear corner of the garage. From here it will extend along behind the rear foundation up to and along the outside of the left side perimeter foundation wall to the left front corner of the garage.
The drainage system consists of a perforated pipe in a rock filled trench to collect sub-surface water. At the upper end or start of the line, as well as at the major corners, a clean out will be provided so that both lines can be tested or cleaned as necessary.
The minimum depth for the perforated pipe will be below the level of the garage slab and the perforated pipe will fall at least 1/8 inch per foot for the total length of the system to the point of discharge.
The perforated pipe will be installed on top of a bed of gravel, two inches deep, with the perforations pointed down. The trench will then be backfilled with drain rock. The rock is Class I, Permeable Type A drain rock per the California State Specifications. The drain rock is clean gravel that varies in size from 1/4 to 1/2 inch. This size rock works best for our type of soil in that it allows the maximum amount of water to penetrate quickly and is small enough to keep out most of the surrounding soil.
The trench will be a minimum of 12 inches wide. This permits a four-inch blanket of rock on each side of the four inch perforated pipe. If the trench that holds the drain is not wide enough, the drain rock will soon become impregnated with dirt from the sides of the trench and will not allow the water to reach the drain pipe.
We will connect the downspout located at the left rear corner of your home into a 4 inch solid pipe and discharge it with the perforated sub-drain approximately 6 feet below the upper driveway.
We will install a moisture barrier on the outside of the left side foundation wall and apply “drylock†to the inside of the foundation.
We will remove and re-install the existing railroad tie steps located along the left side.
We will take care to protect the wood retaining wall located at the left side, but we can not guarantee how well it will withstand the excavation. No retaining wall repair is included.
We will construct the foundation strap on the left side as shown on the Rogers plan. No permits are included.
Once the drainage system has been installed, the sub-area should be monitored during the rainy months to determine if water continues to enter. If so, additional investigation and drainage work will be required.