Soil absorption beds.

El Paso City Code § 18.21.240

in effect

18.21.240 - Soil absorption beds. A. In addition to the trench-type absorption field, two or three absorption beds of reasonably equivalent areas, separated by at least four feet and using water tight flow diversion valving, (See Figure 18.21.240), may be used in areas where the combination of soil percolation and lot size precludes the use of a trench-type system with minimum spacing between trenches. While absorption beds require more bottom area than trenches, they tend to be more compact. B. The bed shall be constructed with its depth ranging from twenty-four inches to thirty-six inches. It shall be kept as shallow as possible to promote aerobic bacterial action in the soil. The bottom of the bed must be level to within plus or minus one inch for uniform wastewater distribution. Fill dirt or top soil shall not be placed on the bed bottom for any reason. Media (gravel, crushed stone, etc.) that is generally one uniform size from 0.75 to two inches shall be placed on the bed bottom followed by two or more distribution pipes spaced six to twelve feet apart and three feet from the edge of the bed. The amount of gravel and spacing between the pipes is dependent on the size of the pipe used. The distribution pipe is then surrounded with additional gravel to the top of the pipe. The pipe must be one size, from three to ten inches in diameter. The total depth of the gravel in the bed is twelve inches. The gravel shall then be covered with filtering material, such as several layers of newspaper, a layer of butcher paper, or geotextile filter fabric, to prevent the final soil layer from invading the gravel and reducing porosity. The next soil layer shall consist of sand, sandy loam, or a mixture of the two. C. Wicks. In order to provide continuous capillary action in the sand, wicks shall be incorporated in the rock media. Wicks are simply sand structures which penetrate through the rock media to the bottom of the bed (See Figure 18.21.240). The total wick area shall be ten to fifteen percent of the bed surface area and shall be uniformly spaced throughout the bed. Wicks may also be constructed by simply grading furrows in the rock media in between the distribution pipe. The total amount of rock media may be reduced by filling the initial twelve inches of the bed with coarse sand (2.0 mm) and placing rock media only around the top, bottom, and sides of the distribution pipe to form an eighteen-inch enclosure. D. Capillary Medium. If clay, rock, or other semi-impervious material is excavated from the bed site, it must be removed and under no circumstances be used as backfill in the bed. Sand or sandy loam will provide a capillary medium to help eliminate some of the wastewater through [image omitted; see the official code] [image omitted; see the official code] evapotranspiration. The bed shall be filled to within six inches from the top with sand or sandy loam and mounded with sandy loam so that the center of the bed is approximately four inches above normal ground elevation. This will provide drainage away from the absorption bed. When this system is used, the total absorption bed area must be calculated using the following formulas: For Dwellings: A = 150 (1 + B) / Ra Where: A = The total absorption bed area required for two beds. B = The total number of bedrooms in the dwelling. Ra = Sewage application rate for absorption trenches expressed as gallons per square foot of bed bottom, per day based on percolation rate. (See Table 18.21.230) For non-single family residential situations: A = 2Q / Ra Where: Q = The total daily wastewater discharge in gallons from that situation. (Ord. 9448 (part), 1988)

Source: City of El Paso, City Code and City Charter (Municode Library, library.municode.com)URL: https://library.municode.com/tx/el_paso/codes/code_of_ordinances?nodeId=TIT18BUCO_CH18.21PRSEFA_ARTVIDESTEFDISY_18.21.240SOABBEFetched: 10/28/2026