11-4-3: SEPTIC TANK SYSTEMS:

   A.   Limitations For Septic Tank Systems: The following criteria shall be used to determine the minimum lot size for on site septic filter field systems:

   DEGREE OF LIMITATION

Item Affect- ting Use	Small Lot	Medium Lot	Large Lot	Prohibited
Slope	1% – 8%	8% – 15%	15% – 20%	Less than 1% or more than 20%
Depth to rock, hard pan or other impervious material (distance below drain field)	Over 25'	15' – 25'	10' – 25'	Less than 10'
Depth to water table (distance below drain field)	Over 15'	10' – 15'	6' – 10'	Less than 6'
Flooding	None	Rare -not more than once in 5 years	Occasional not more than one per year	Frequent - in floodplain
Map "Efficiency of Soils for Septic Filter Field Use"	Slight	Moderate	Severe	Severe
Soil type (USDA map)	Identify soil type from U.S. department of agriculture map
Filled areas	Maximum fill 5'. Filling does not change degree of limitation
Distance from stream or lake	Over 200'	150' - 200'	100' - 150'	Less than 100'
Minimum lot size	1 acre1	3 acres1	5 acres1	Not permitted1
1 Any lot having one or more factors under a more restrictive condition will be placed under the larger lot size requirement, even though other criteria for that lot may be more favorable.

 

   B.   Subsurface Seepage Field, Dosage Rate:

Time Required For Water To Fall 6 inches (minutes)	Effective Absorption Area Required In Bottom Of Seepage Fields (sq. ft./bedroom)	Maximum Rate Of Sewage Application (gallons per square foot per day) For Subsurface Seepage Fields, Seepage Beds
30	130	2.2
60	165	1.6
90	210	1.3
120	235	1.1
150	265	1.0
180	290	0.9
240	320	0.8
300	350	0.7
360	385	0.6
1. Absorption area is figured as trench bottom area.
2. Over 180 unsuitable for seepage pits.
3. Over 360 unsuitable for absorption systems.

 

   (1976 Code § 152.027)