25 Pa. Code § 73.16 - Absorption and spray field area requirements

(a) General. Absorption areas and spray fields for single family dwellings not served by a community sewage system shall be designed based on a minimum flow of 400 gpd for all dwellings having three bedrooms or less. The minimum flow of 400 gpd shall be increased by 100 gpd for each bedroom over three.

(b) Absorption areas.

(1) Only the bottom of the aggregate area of the bed or trench shall be used in calculating absorption area requirements.

(2) Absorption area requirements for single family dwellings served by a community sewage system and for apartments or nonresidential establishments served by an individual onlot or community onlot sewage system shall be designed based on flows listed in § 73.17 (relating to sewage flows) for the type of facility to be served.

(3) For nonresidential establishments, a volume of 200 gpd shall be the minimum volume used in calculating the size of the absorption area.

(c) Required absorption area. Table A shall be used in calculating the square footage of absorption area required based on flows determined in subsections (a) and (b). Table A includes allowances for garbage grinders, automatic washing machines or dishwashers and water softeners.

(d) Substitute. When a substitute for aggregate, such as a leaching chamber, large diameter pipe, or other material or device, is used in the absorption area, subsection (b)(1) applies.

TABLE A

Minimum Aggregate Absorption Area Requirements for Treatment Tank Effluent:

Square Feet of Aggregate Area Per Gallon Per Day
Average Percolation Rate Expressed as Minute Per Inch	All Systems Except Elevated Sand Mounds and Subsurface Sand Filters	Subsurface Sand Filters and Elevated Sand Mounds
Less than 3.0D	Unsuitable	Unsuitable
3 - 5C	Unsuitable	1.50AB
6 - 15C	1.19B	1.50AB
16 - 30C	(Avg. Perc Rate - 15) x (0.040) + 1.19B	1.50AB
31 - 45C	(Avg. Perc Rate - 30) x (0.030) + 1.79B	(Avg. Perc Rate - 30) x (0.026) + 1.50AB
46 - 60C	(Avg. Perc Rate - 45) x (0.028) + 2.24B	(Avg. Perc Rate - 45) x (0.022) + 1.89A
61 - 90C	(Avg. Perc Rate - 60) x (0.023) + 2.66A	(Avg. Perc Rate - 60) x (0.020 ) + 2.22A
91 - 120ACD	Unsuitable	(Avg. Perc Rate - 90) x (0.017 ) + 2.82A
121 - 150CD	Unsuitable	((Avg. Perc Rate - 120) x (0.015 ) + 3.33) (1.05)A
151 - 180CD	Unsuitable	((Avg. Perc Rate - 150) x (0.014 ) + 3.78) (1.10)A
Greater than 181CD	Unsuitable	Unsuitable

A Pressure dosing required.

B One third reduction may be permitted for use of an aerobic tank.

C May be considered for experimental or alternate proposals.

D Unsuitable for subsurface sand filters.

(e) Spray fields. Table B shall be used in calculating the square footage of spray fields based on flows determined in Subsection (a). Table B includes allowances for garbage grinders, automatic washing machines, dishwashers and water softeners.

TABLE B

Soil Characteristics		Slope	Required Spray Field Area (Ft 2)
Depth To Rock	Depth To Water Table	3 Bedroom Home	Additional Area Per Bedroom
16 to 20 inches	10 to 40 inches	[GREATER THAN EQUAL TO]12%	40,000	10,000
		>12%	80,000	20,000
	>40 inches	[GREATER THAN EQUAL TO]12%	15,000	3,750
		>12%	30,000	7,500
>20 inches	10 to 20 inches	[GREATER THAN EQUAL TO]12%	20,000	5,000
		>12%	40,000	10,000
	>20 inches	[GREATER THAN EQUAL TO]12%	10,000	2,500
		>12%	20,000	5,000

Notes

25 Pa. Code § 73.16

The provisions of this § 73.16 adopted January 21, 1983, effective 1/22/1983, 13 Pa.B. 508; amended November 7, 1997, effective 11/8/1997, 27 Pa.B. 5877; corrected November 21, 1997, 27 Pa.B. 6079.

The provisions of this § 73.16 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).

This section cited in 25 Pa. Code § 71.52 (relating to content requirements-new land development revisions); 25 Pa. Code § 71.63 (relating to retaining tanks); 25 Pa. Code § 72.22 (relating to permit issue); 25 Pa. Code § 73.14 (relating to site investigation); 25 Pa. Code § 73.15 (relating to percolation tests); 25 Pa. Code § 73.54 (relating to subsurface sand filters); 25 Pa. Code § 73.161 (relating to general); and 25 Pa. Code § 73.163 (relating to spray fields).