| (a) Introduction.
(1) Purpose. Hyacinths may be used for the removal
of suspended solids from secondary effluent. Other proposed treatment
applications, however, are not excluded by these criteria, and such
proposals will be reviewed on a case-by-case basis.
(2) Other permits. The authority to use hyacinths is
contingent upon obtaining a possession permit from the Texas Parks
and Wildlife Department.
(3) Location. Uncovered hyacinth basins will be approved
only in Cameron, Hidalgo, Kenedy, and Willacy Counties. Hyacinth basins
elsewhere shall be covered with a greenhouse structure. A variance
will be considered for systems which are designed for seasonal operation.
Greenhouse design shall provide for adequate dike top width for equipment
maneuverability, doors for personnel and equipment access, and openings
for ventilation.
(b) Design.
(1) Multiple basins. Multiple basins shall be provided.
Capacity to treat the design flow with one basin out of service shall
be provided. A variance may be considered for systems which are designed
for seasonal operation. Average water depth of basin shall not exceed
36 inches.
(2) Basin sizing and configuration. Multiple surface
inlets and outlets shall distribute flow uniformly through the basin.
This may be accomplished by a weir, openings in a baffle, by a perforated
pipe, or other methods. Basins of one acre or less in size are required.
The bottom of the hyacinth basin shall be sloped to facilitate draining.
A surge basin or some other method of flow equalization to achieve
a more constant rate of inflow to the basin is desirable.
(3) Barrier. A fixed barrier creating a clear zone
shall be installed at the outlet to prevent the discharge of hyacinths
or hyacinth seed. While screening may be used as a barrier material,
a permeable rock barrier is preferred. Water depth within the outlet
area shall not be more than 24 inches with the bottom covered by a
layer of broken rock or washed gravel.
(4) Loading. Organic loading of hyacinth basins shall
not exceed 100 pounds per acre per day of five-day biochemical oxygen
demand (BOD5 ) unless supplemental aeration
is provided to consistently maintain an aerobic surface water layer.
The maximum hydraulic loading shall not exceed 0.20 million gallons
per day per acre.
(5) Natural aerators and mosquito control. Exclosures
shall be placed at intervals along basin edges to provide clear zones
for aeration and to enhance fish production for mosquito control.
Total area of exclosures should be approximately 20% of total basin
area. Exclosures shall have a uniform depth of not more than 24 inches,
with bottoms lined with broken rock or washed gravel. Plastic sheeting
covered with a layer of broken rock or washed gravel, extending above
and below operating water level, shall be placed all along inner basin
berms to prevent weed growth and eliminate a mosquito breeding habitat.
(c) Operation.
(1) Harvesting. Adequate provisions for access, removal,
and disposal of the hyacinth plants shall be provided. Removal shall
be done mechanically.
(2) Cleaning. Each basin shall be cleaned once each
year by dewatering and removing plants and sludge.
(3) Coverage. Plant coverage shall be limited to 90%
of the basin area.
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