Agriculture Reference
In-Depth Information
2.
Ground settlement may have caused a depression.
3.
The road to the left may have been redone, creating a dam to block water
draining from the parking lot.
In nearly every site-grading design problem, there are several alter-
native solutions for handling storm water. Which is the best solution
depends on project budget, governmental requirements, design consid-
erations, and functional activities and uses.
Soil erosion is caused by water moving across the ground surface
as a concentrated, fast-moving flow, or by a surface water sheet flowing
over a steep slope. Figure 14.4 shows the result of storm water that has
backed up along a parking lot curb, spilling over the side then moving
down a steep, poorly maintained slope. Over time the erosion became
worse as the slope became increasingly exposed with the loss of grass to
protect and hold the soil.
Examples of different approaches to handling surface storm water
are described in the following sections. The examples represent a broad
range of approaches to collecting, storing, and transporting storm water.
In some cases the water is stored on-site, and in other examples the
water is collected then carried off-site by an underground pipe or canal
to a municipal storm water dis-
posal system. In today's world,
where sustainable design and
best water management practices
are steadily becoming the norm,
site-grading designs incorporate
a range of strategies for main-
taining water on-site, in reten-
tion ponds or water gardens, or
stored for later uses such as for
irrigation. Other grading design
approaches direct and slow down
surface water to allow absorp-
tion into the soil and to recharge
underground aquifers.
Figure 14.4
Slope erosion adjacent to a parking lot
