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Onsite
Sewage Disposal
Feasibility
Did you know that in
Virginia
approximately one third of all homes are served onsite sewage disposal or
septic systems? The
Environmental Protection Agency has deemed pollution from old, failing, and
outdated onsite systems to be one of the largest sources of groundwater
contamination in the
US
. In response, states have
strengthened their onsite sewage regulations in order to protect public health.
Many of these changes have resulted in the requirement for alternative,
or advanced onsite systems to be used in areas where conventional septic systems
were once allowed. In addition,
states now require be more stringent controls on who evaluates sites and designs
these systems.
Virginia
’s Authorized Onsite Soil Evaluator (AOSE) program was introduced to
facilitate proper design of onsite wastewater systems.
An AOSE is an environmental professional who has experience and training
evaluating sites for onsite sewage disposal.
AOSE’s are also required to complete Virginia Department of Health
testing to ensure that they are competent to perform soil evaluations and design
onsite systems.
A soil evaluation, commonly and
inaccurately called a “Perc Test,” is a systematic evaluation of the
critical items related to ensure that an onsite sewage disposal system complies
with the Virginia Department of Health 2000 Sewage Handling and Disposal
Regulations. The critical items
determined by a soil evaluation are as follows:
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The
depth of seasonal water table. A
standoff or separation distance from the bottom of the onsite system to a
seasonal water table is paramount in protecting groundwater.
The standoff allows the natural organisms in the unsaturated soil to
quickly out compete and kill off the harmful pathogens found in sewage.
This standoff varies from system to system, but generally decreases
as the level of treatment provided by the system increases. |
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Texture
of soil, the heaver the texture of the soil the larger the absorption field
needs to be for any given flow. Example:
a 4 bedroom house whose system in located in heavy clay soil will be larger
than a 4 bedroom system located in very sandy soil. |
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Sanitary
survey is critical to determine if the horizontal separation distances
required in
Virginia
’s 2000 Sewage Handling and Disposal Regulations and 1992
Private Well Regulations can be maintained.
Both sets of regulations contain the required horizontal setbacks
from onsite systems and other sources of contamination (i.e. UST’s) to all
types of wells. In layman terms,
you do not want to put a septic system to close to a well or vice versa. |
By performing a soil evaluation and associated sanitary survey, an AOSE can
determine any particular site’s feasibility for an onsite sewage disposal
system, and design a system that will best serve the client’s needs today and
in the future.
For further information, please call
Mr. Quinn Zimmerman, Authorized Onsite Soil Evaluator#238 at Stokes
Environmental Associates 757-623-0777 or qzimmerman@stokesea.com. Mr. Zimmerman
has extensive experience performing soil evaluations to determine suitability
for onsite sewage disposal, including Conventional, Alternative, and Soil
Drainage Management systems.
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