TranSystems Corporation - LGM Construction

8.1.4 Site Drainage
Proper site drainage is important for the long-term performance of the planned
structure. The site should be graded so as to carry surface water away from the
building foundations, at a minimum slope of 2 percent at least 5 feet laterally from the
building. In addition, all roof gutters should be connected directly into a storm drainage
system, or drain onto impervious surfaces that drain away from the buildings, provided
that a safety hazard is not created.
8.1.5 Wet Weather Construction
If site grading and construction is to be performed during the winter rainy months, the
owner and contractors should be aware of the potential impact of wet weather.
Rainstorms can cause delay to construction and damage to previously completed work
by saturating compacted pads or subgrades, or flooding excavations.
The grading contractor should be responsible to protect his work to avoid damage by
rainwater. Standing pools of water should be pumped out immediately. Construction
during wet weather conditions should be addressed in the project construction bid
documents and/or specifications. We recommend the grading contractor submit a wet
weather construction plan outlining procedures they will employ to protect their work
and to reduce damage to their work by rainstorms.
8.2 FOUNDATIONS
8.2.1 Mat Foundation
The proposed building can be supported on a mat foundation bearing on the existing fill.
The allowable bearing pressure beneath the mat should not exceed 2,000 psf for dead
plus live loads. This bearing pressure may be increased by 1/3 for supporting total
loads, including wind and seismic loads. These values include a factor of safety of at
least 3.0. Excavations for the mat slab should be free of loose soils, debris and
standing water prior to placing concrete.
For elastic analysis of the mat and determination of deflections we recommend a
modulus of vertical subgrade reaction of 50 kips per cubic foot (kcf) be used.
94240/1(OAK8R061)/es Page 20 of 29 June 13, 2008
© 2008 Kleinfelder