Scope of Work
We will construct a drainage system along the right, rear, and left sides of your home. The system will start on the right side adjacent the rear of the garage with a trench 2 feet deep. From here it will extend along the right side to the rear corner, along the rear to the left corner, then along the left side to the front corner.
The drainage system consists of two pipes in a rock filled trench.Â One is perforated, to collect sub-surface water and the other is non-perforated, to collect water from the roof downspouts.Â At the upper end or start of both lines, 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 grade of the soil under the house and both the perforated and non-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.Â The trench will then be then backfilled with drain rock.Â The rock we recommend is Class I, Permeable Type A drain rock per the California State Specifications.Â The drain rock is clean gravel that varies in size from 1/4 to 1/2 inch.
The trench will be a minimum of 12 inches wide.Â This permits a four inch blanket of rock on each side of the four inch perforated pipe.
The system will discharge through a 4 inch solid pipe across the front yard to the street. On the yard side of the public walk we will install a 12 inch catch basin in the low area.
We will remove and replace 2 sections of concrete adjacent the right rear corner. The new concrete will slope away from the house. We will remove and replace a strip of concrete across the public walk.
We will replace all the concrete removed with concrete to match the existing as close as we can, but it will still be noticeably different.Â It is impossible for the new concrete to exactly match the old.
We will remove and replace the existing rear deck boards as necessary.
Our prices for underground work, drilling, trenching or digging are based on soil conditions visible on the surface at the time of our inspection.Â Even if a subsurface soil investigation has been done by a competent soil engineer, this tells what the conditions are at the test site only.Â A few feet away different conditions may exist.Â If we encounter any subsurface conditions which require additional work such as, excessive ground water, cave-ins, loose fill, hard rock or other underground obstructions that require a change of method or change of location or change of equipment for the completion of the underground work, you should anticipate an increase in the cost of the job.Â The contract price for the work specified is based on ideal conditions and no extra work is included.
Owner will be notified by contractor when any of the above conditions occur.
All rock, hard ground, or buried concrete that requires an electric or pneumatic chipping hammer or jackhammer for excavation will be billed hourly in addition to the contract price.
Once the drainage system has been installed the sub-area should be monitored during the rainy months to determine if water continues to enter.Â If so, additional investigation and drainage work will be required.