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The Pennsylvania Code website reflects the Pennsylvania Code changes effective through 54 Pa.B. 2336 (April 27, 2024).

25 Pa. Code § 73.51. General.


§ 73.51. General.

 (a)  In all systems, if an absorption area is proposed, the top of the limiting zone shall be at least 4 feet below the bottom of the aggregate. Coarse aggregate used in the distribution system shall meet the requirements of the Department of Transportation specifications, Publication #408 (1994) section 703 available from the Department of Transportation. The size and grading of the aggregate shall meet AASHTO No. 57 requirements from a PADOT certified stockpile and shall be of Type B quality requirements.

   (1)  Where the depth to the top of the limiting zone is 60 inches or greater, the system shall be installed so that the bottom of the aggregate is a minimum of 4 feet above the limiting zone.

   (2)  Where the depth to the top of the limiting zone is less than 60 inches, an elevated sand mound is required. Isolation from the limiting zone shall be achieved as required by §  73.55(a)(3)—(5) (relating to elevated sand mounds).

   (3)  An absorption area may not be installed where less than 20 inches of suitable undisturbed mineral soil exists.

   (4)  When infiltration chambers or other devices which require no aggregate are used, adequate provisions to protect the infiltrative surfaces from damage by operation of pressure distribution systems shall be made.

 (b)  Before and after installation, equipment and vehicles shall be kept off the proposed absorption area, including the downslope area, to prevent undue compaction of the soil. Care shall be exercised during construction to prevent undue compaction and damage to the system and the downslope area.

 (c)  Soil moisture levels during construction of the absorption area shall be such that a sample of natural mineral soil taken from the level of the proposed installation will crumble if compressed into a ball.


   The provisions of this §  73.51 amended under section 9 of the Pennsylvania Sewage Facilities Act (35 P. S. §  750.9); The Clean Streams Law (35 P. S. § §  691.1—691.1001); and section 1920-A of The Administrative Code of 1929 (71 P. S. §  510-20).


   The provisions of this §  73.51 adopted August 2, 1971, effective August 14, 1971, 1 Pa.B. 1649; amended April 26, 1974, effective May 13, 1974, 4 Pa.B. 817; amended August 30, 1974, effective September 16, 1974, 4 Pa.B. 1805; amended January 21, 1983, effective January 22, 1983, 13 Pa.B. 508; amended November 7, 1997, effective November 8, 1997, 27 Pa.B. 5877. Immediately preceding text appears at serial pages (217331) to (217332).

Cross References

   This section cited in 25 Pa. Code §  71.63 (relating to retaining tanks); and 25 Pa. Code §  73.54 (relating to subsurface sand filters).

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