Effectiveness and Performance of Groundwater
Modification Systems
Effectiveness and Performance of Groundwater Modification
Systems
Dr Robert Evans
Dept Of Bio & Ag Engineering
N C State Univ
Box 7625
Raleigh NC 27695
In high water table soils, wetness limitations can sometimes be
overcome by installing perimeter drainage. Drainage system
effectiveness is highly dependent on soil properties, system
design taking into account the site specific conditions, proper
installation, and proper system maintenance. Poor performance of
septic systems in drained soils has often been attributed to a
belief that certain soils cannot be drained. To the contrary, the
water table can be lowered in all soils. However, merely lowering
of the water table does not ensure that adequate soil aeration
will be provided for proper septic system performance. In
considering drainage as an alternative, it is also important to
evaluate the drained porosity of the soil. In addition, the
drainage intensity required to effectively lower the water table
in tighter, heavier textured soils may not be practical when
septic system setback regulations are imposed. Poor septic
system performance in drained soils can often be linked to
improper installation and, or lack of drainage system
maintenance. The tow most important components of a water table
lowering system is an adequate drainage outlet and efficient
removal of excess surface water. Deep drainage ditches are often
required to provide an adequate drainage outlet. Homeowners don
t like deep drainage ditches because they are difficult to mow
and maintain and thus can become unsightly. Low spots in the
ditch may trap surface water providing a stagnant pool for
mosquito to breed. Large ditches with standing water are inviting
playgrounds to small kids and thus can pose a safety risk. As a
result, homeowners are quick to fill drainage ditches not
realizing that the ditch provides the outlet required for proper
performance of their drainage and septic systems. Proper lot
grading and landscaping are required to achieve effective surface
drainage. For drainage systems to work properly, homeowners must
understand their function and be committed to providing the
required maintenance of the system.
Please address any questions to Dr. David Lindbo.
This page created by
Roland O.
Coburn,
Research Technician I
on 1/10/03.