(2) The main objective in the design of an
concentration of the land-limiting constit-
ocean outfall is the enhancement of dilution of
--Select the most cost-effective combina-
wastewater in marine waters. This is achieved by
tion of pretreatment and land application
installing a multiple port diffuser through which
wastewater is discharged. This dilution, referred
to as "initial dilution", is primarily dependent on
(2) Land application design has a highly
site-specific character and requires careful devel-
the depth of sea at the point of discharge.
opment of the individual solution. Failures of
(3) The wastewater plume which forms at the
existing systems have been most frequently at-
sea surface above the diffuser is subject to ocean
tributed to not considering the site-specific nature
currents, turbulent mixing, and wave and wind
of this disposal method.
effects. This results in further dilution referred to
as "turbulent dilution." The intensity of this
(3) Determination of the land application rate
for any industrial waste constituent is based on a
dilution depends mainly on the natural turbulence
in the ocean.
calculation of the mass balance of this constituent
in the soil system. The result of these calculations
(4) Ocean dumping of industrial waste is
is the application rate, expressed in lb/acre-yr,
closely regulated by the U.S. EPA. Before per-
that will not exceed the environmentally accepted
mits are issued several studies have to be con-
levels of pollutant in any part of the system.
There are no standard application rates for all
investigations. Therefore, this approach should be
types of soils and each case should be treated
taken only as a last resort when inland treatment
and disposal are not feasible.
e. Deep well injection. Deep well injection is a
d. Land application. Land application of
wastewater is a treatment approach in which the
disposal method in which industrial wastes are
characteristics of the wastewater are altered by
stored in subsurface strata of proper characteris-
microbial stabilization, adsorption, immobilization
tics. The technology of deep well injection was
and crop recovery. Industrial wastes are applied
described in detail by Warner (165).
to the land at rates that are low enough not to
(1) Deep well applications.
exceed the assimilative capacity of the soil.
(a) Deep wells have been used extensively
Pretreatment processes are almost always neces-
for many years in oil producing regions to return
sary to reduce toxic or pollutant species which
large quantities of saline water underground.
increase land requirements, and thus, improve the
However, due to the uncertainties involved and
overall economics of the total system. Land
the regulatory constraints, they have not been
application has not been widely used for indus-
used extensively for industrial waste disposal.
trial wastes due to the complexity of the waste-
(b) The approval of a new injection well for
waters and the lack of proven design criteria.
industrial waste disposal requires investigation of
However, it is now believed that an environmen-
alternative methods which concludes that an
tally acceptable rate of application can be deter-
injection well is the most environmentally satis-
mined for any and all domestic and industrial
factory option. Drilling of a preinjection test well,
waste constituents with the exception of radioac-
monitoring provisions, contingency plans and pro-
visions for capping of wells after shutdown are
(1) Land application design. A rational ap-
also required. Even though this method may not
proach to developing a land application solution
be of widespread application, for a specific waste,
should proceed in the following sequence:
it may be the most environmentally accepted
--Determine the controlling parameter in
the wastewater based on the assimilative
(2) Considerations for design.
capacity of the plant-soil system and the
(a) The most important consideration in
waste load on a constituent-by-constitu-
developing deep well injection concerns the pro-
ent basis. The controlling parameter is
tection of underground water resources from
that constituent which requires the great-
being contaminated by the industrial wastes. This
est land area.
means that the wastes must remain confined in a
--Economically evaluate all components re-
specified zone and not diffuse into strata which
quired for the land application system
were not designated for wastewater storage. The
under various levels of the land-limiting
well area and its casing must be designed and
--Economically evaluate pretreatment or
constructed to avoid upward migration of fluid
in-plant modifications for reducing the
from the injection well. A comprehensive monitor-