Section R18-9-E321. 4.21 General Permit: Surface Disposal, Less Than 3000 Gallons Per Day Design Flow

A.      A 4.21 General Permit allows for surface application of treated wastewater that is nominally free of coliform bacteria pro- duced by the treatment works of an on-site wastewater treat- ment facility.

B.       Performance. An applicant shall ensure that the treated waste- water distributed for surface application meets the following criteria:

1.        TSS of 30 milligrams per liter, 30-day arithmetic mean;

2.        BOD5 of 30 milligrams per liter, 30-day arithmetic mean;

3.        Total nitrogen (as nitrogen) of 53 milligrams per liter,

five-month arithmetic mean;

4.        Is nominally free of total coliform bacteria as indicated by a total coliform level of Log10  0 colony forming units per 100 milliliters, 95th percentile.

C.      Restrictions. The applicant shall not install the disposal works if weather records indicate that:

1.        Average minimum temperature in any month is 20°F or less, or

2.        Over 1/3 of the average annual precipitation falls in a 30- day period.

D.      Design requirements. An applicant shall ensure that:

1.        The land surface application rate does not exceed the lowest application rate as determined under R18-9- A312(D) minus no greater than 50 percent of the evapo- transpiration that may occur during the month with the least evapotranspiration in any soil zone within the top 5 feet of soil;

2.        The design incorporates sprinklers, bubbler heads, or other dispersal components that optimize wastewater loading rates and prevent ponding on the land surface;

3.        The design specifies containment berms:

a.         Compacted to a minimum of 95 percent Proctor;

b.        Designed to contain the runoff of the 10-year, 24- hour storm event in addition to the daily design flow; and

c.         Designed to remain intact in the event of a more severe rainfall event; and

4.        The design incorporates placement of signage on hose bibs, human ingress points to the surface disposal area, and at intervals around the perimeter of the surface dis- posal area to provide notification of use of treated waste- water and a warning against ingestion.

E.       Installation requirements. An applicant shall ensure that instal- lation of the wastewater dispersal components conforms to manufacturer’s specifications that do not conflict with this Article and to the design documents specified in the Construc- tion Authorization issued under R18-9-A301(D)(1)(c).

F.       Operation and maintenance. In addition to the requirements specified in R18-9-A313(B), the permittee shall operate and maintain the surface disposal works to:

1.        Prevent treated wastewater from coming into contact with drinking fountains, water coolers, or eating areas;

2.        Contain all treated wastewater within the bermed area; and

3.        Ensure that hose bibs discharging treated wastewater are secured to prevent use by the public.

Historical Note

New Section adopted by final rulemaking at 7 A.A.R. 235, effective January 1, 2001 (Supp. 00-4). Section repealed; new Section made by final rulemaking at 11

A.A.R. 4544, effective November 12, 2005 (Supp. 05-3).