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-723 - Sand Filter [formerly Section V of Appendix A]

Current through Register Vol. 50, No. 6, June 20, 2024
A. [Formerly paragraph A:5.1 of Appendix A]
				  Another alternative for the secondary treatment of septic tank effluent is a
				  deep-type sand filter bed. Treatment in a sand filter bed is accomplished by
				  the action of microorganisms in a sand bed in which the suspended solids of the
				  septic tank effluent have been trapped by filtration. It is important that the
				  sand bed remain aerobic throughout the treatment process. This is accomplished
				  by exposing the sand surface to the air as much as possible on a continuous
				  basis. Of course, the best way this can be done is to place no cover whatsoever
				  over the sand bed. Since this is not aesthetically desirable for homes, a
				  coarse gravel cover of clean, washed gravel, not to exceed 6 inches in depth
				  over the bed is permitted. No other cover is acceptable. A filter bed system is
				  shown in §1501. B.9 (Figure 9).
B.
				  [Formerly paragraph A:5.2 of Appendix A] The sand filter bed is constructed by
				  placing perforated pipe near the bottom of a rectangular area of the required
				  size in a layer of gravel covered by a layer of coarse sand 24 inches deep. On
				  top of this are placed distribution lines (perforated pipe) likewise encased in
				  a layer of gravel [see §1501. B 10 (Figure 10)]. The septic tank effluent is
				  distributed speedily in the gravel cover spreading over the top of the sand
				  seeping slowly and vertically through the sand to the bottom layer of gravel to
				  be carried away in the under drain line.
C. [Formerly paragraph A:5.3 of Appendix A]
				  Sand filter beds are to be constructed with a minimum width of 12 feet and a
				  minimum length of 25 feet. This minimum size filter bed is adequately sized for
				  design flows of up to 400 gpd. For greater design flows, the required length
				  shall be increased by eight feet for each additional 150 gpd or portion
				  thereof.
D. [Formerly paragraph
				  A:5.4 of Appendix A] The bed must be drained completely. This may require the
				  bed to be raised above natural ground level.
E. [Formerly paragraph A:5.5 of Appendix A]
				  To prevent sand infiltration into the underdrain, a layer of graded gravel must
				  be placed over the underdrain line and the entire bottom of the filter bed. All
				  gravel must be clean and washed.
F.
				  [Formerly paragraph A:5.6 of Appendix A] Filter sand shall conform to the
				  following standard specifications.
U.S.
Sieve Size
Tyler
Screen Size
% Passing
(By Weight)
Number 4
Number 4
95-100
Number 14
60-80
Number 16
Number 28
5-20
Number 50
Number 48
0-5
Number 100
Number 100
0
G.
				  [Formerly paragraph A:5.7 of Appendix A] At least two distribution lines must
				  be provided and they must be sloped 2 inches to 3 inches per 100 feet. The
				  lines must be 4-inch diameter, 20-inch long farm tile, 2 feet to 3-feet lengths
				  of vitrified clay bell-and-spigot sewer pipe laid with open joints, or
				  perforated nonmetallic pipe meeting one of the standards cited in §719. M The
				  ends of the distribution lines must be half-closed [see §1501. B 10 (Figure
				  10)].
H. [Formerly paragraph A:5.8
				  of Appendix A] Underdrain pipe materials are the same as those for the
				  distribution pipe, however, the slope must be no less than 4 inches per 100
				  feet.
I. [Formerly paragraph A:5.9
				  of Appendix A] The filter bed must be appropriately protected from surface
				  runoff water.
J. [Formerly
				  paragraph A:5.10 of Appendix A] The filter bed must be located no less than 10
				  feet from the property line.
K.
				  [Formerly paragraph A:5.11 of Appendix A] The location of the filter bed shall
				  comply with minimum distance requirements from water wells, water lines, etc.,
				  as contained in Part XII of this Code.
The address cited in §725. G has changed to:
Department of Health and Hospitals
Office of Public Health
Engineering Services Section
P.O. Box 4489
Baton Rouge, LA
						70821-4489
AUTHORITY NOTE:
					 Promulgated in accordance with
					 R.S.
					 40:4(A)(6) and
					 R.S.
					 40:5(9)(20).