Louisiana Administrative Code › Title 51 - PUBLIC HEALTH-SANITARY CODE › Part XIII - Sewage Disposal › Chapter 7 - Individual Sewerage Systems [formerly Chapter 13 Subpart D] › Subchapter B - Design and Construction Regulations [formerly Chapter 13 Appendix A] › Section XIII-721 - Oxidation Ponds [formerly Section IV of Appendix A]

Current through Register Vol. 50, No. 6, June 20, 2024
A. [Formerly paragraph A:4.1 of Appendix A]
				  An oxidation pond is a shallow pond designed specifically to treat sewage by
				  natural purification processes under the influence of air and sunlight. The
				  stabilization process consists largely of the interactions of bacteria and
				  algae. Bacteria digest and oxidize the constituents of sewage and render it
				  harmless and odor free. Algae utilize carbon dioxide and other substances
				  resulting from bacterial action and through photosynthesis produce the oxygen
				  needed to sustain the bacteria in the treatment process. During the detention
				  period, the objectionable characteristics of the sewage largely
				  disappear.
B. [Formerly paragraph
				  A:4.2 of Appendix A] The minimum surface area of an oxidation pond must be no
				  less than 400 square feet with a 4 to 5 foot average liquid depth and vertical
				  side walls. This minimum size pond is adequate for design flows of up to 400
				  gallons/day (gpd). For design flows in excess of 400 gpd, the pond area must be
				  increased to provide sufficient volume (at the 4 foot depth) to hold 30 days
				  worth of flow (a 30-day retention period). For wastes with high BOD loadings,
				  special consideration for increasing pond size must be given.
C. [Formerly paragraph A:4.3 of Appendix A]
				  Section 1501. B.5 (Figure 5) shows a typical layout for a septic tank-oxidation
				  pond system. The actual layout of any pond system will be governed to a great
				  extent by the topography of the particular location. However, an oxidation pond
				  must be located so as to comply with the minimum distance requirements from
				  water wells, lines, etc., as contained in Part XII of this Code. It is also
				  desirable for aesthetic reasons to locate it as far as possible, but at least
				  50 feet from any dwelling and no less than 20 feet from the property line to
				  water's edge at normal operating line.
D. [Formerly paragraph A:4.4 of Appendix A]
				  As mentioned, the use of the minimum surface area of 400 square feet requires
				  that an oxidation pond be furnished with vertical side walls so that an
				  adequate volume for treatment is provided. Section 1501. B.6 (Figure 6) shows a
				  type of construction utilizing treated timber which under normal soil
				  conditions is acceptable for the vertical side walls of a 20 foot by 20 foot
				  oxidation pond with a 5 foot average water depth. Section 1501. B.7 (Figure 7)
				  shows a similar type of construction utilizing concrete blocks. Either of these
				  designs requires very little maintenance.
E. [Formerly paragraph A:4.5 of Appendix A]
				  Vertical side walls must be of cypress or treated timbers or concrete blocks
				  and so constructed as to provide a permanent structure.
F. [Formerly paragraph A:4.6 of Appendix A]
				  Although not encouraged, a pond may be constructed with sloping sides and
				  earthen levees. Such a design is shown in §1501. B.8 (Figure 8). The design
				  requires a minimum surface area of 625 square feet with a 5 foot liquid depth
				  at the center in order to achieve the required volume. The cost of this design
				  is less than that of the vertical wall ponds referred to above, but more space
				  is needed and routine maintenance requirements such as levee mowing are
				  greater. The slope of the natural earth side walls must not be shallower than
				  one-to-one (45-degree angle) [see §1501. B.8 (Figure 8)].
G. [Formerly paragraph A:4.7 of Appendix A] A
				  septic tank must precede the oxidation pond and must comply with the septic
				  tank requirements presented in these regulations.
H. [Formerly paragraph A:4.8 of Appendix A]
				  The pipe from the septic tank to the pond as well as the outfall pipe from the
				  pond must be at least 4 inches in diameter and placed at a minimum slope of 2
				  inches per 100 feet. The inlet must extend 4 to 6 feet horizontally into the
				  pond and be directed downward at least 1 1/2 to 2 feet below the liquid surface
				  level. The outlet must extend 4 to 6 feet horizontally into the pond and
				  consist of a tee with the invert set at the operating water level of the pond.
				  One leg of tee must be open and extend above the water level, while the down
				  leg is extended 1 1/2 to 2 feet below the water level. The invert of the pond
				  outlet must be lower than the pond inlet invert [see §1501. B.8 (Figure 8)].
				  Additionally the invert of the pond inlet must be at least 2 inches lower than
				  the invert of the septic tank outlet.
I. [Formerly paragraph A:4.9 of Appendix A]
				  The pond shall be enclosed by a suitable non-climbable fence to keep out
				  children, pets and livestock. An open type fence (woven wire) is preferable
				  because it will not restrict sunlight and air which are necessary for the
				  treatment. The fence shall be at least 5 feet in height and be provided with a
				  locked gate.
J. [Formerly paragraph
				  A:4.10 of Appendix A] Abandoned oxidation ponds (ponds no longer in active use)
				  shall be dewatered, allowed to dry and then filled with soil to natural
				  grade.
AUTHORITY NOTE:
					 Promulgated in accordance with
					 R.S.
					 40:4(A)(6) and
					 R.S.
					 40:5(9)(20).