North Carolina Administrative Code
Title 15A - Environmental Quality
Chapter 18 - ENVIRONMENTAL HEALTH
Subchapter A - ENVIRONMENTAL HEALTH
Section .1900 - SEWAGE TREATMENT AND DISPOSAL SYSTEMS
Section 18A .1949 - SEWAGE FLOW RATES FOR DESIGN UNITS

Universal Citation: 15A NC Admin Code 18A .1949

Current through Register Vol. 39, No. 6, September 16, 2024

(a) In determining the volume of sewage from dwelling units, the flow rate shall be 120 gallons per day per bedroom. The minimum volume of sewage from each dwelling unit shall be 240 gallons per day and each additional bedroom above two bedrooms shall increase the volume of sewage by 120 gallons per day. In determining the number of bedrooms in a dwelling unit, each bedroom and any other room or addition that can reasonably be expected to function as a bedroom shall be considered a bedroom for design purposes. When the occupancy of a dwelling unit exceeds two persons per bedroom, the volume of sewage shall be determined by the maximum occupancy at a rate of 60 gallons per person per day.

(b) Table No. I shall be used to determine the minimum design daily flow of sewage required in calculating the design volume of sanitary sewage systems to serve selected types of establishments. The minimum design volume of sewage from any establishment shall be 100 gallons per day. Design of sewage treatment and disposal systems for establishments not identified in this Rule shall be determined using available flow data, water-using fixtures, occupancy or operation patterns, and other measured data.

TABLE NO. I

TYPE OF ESTABLISHMENT

DAILY FLOW FOR DESIGN

Airports

5 gal/passenger

(Also R.R. stations, bus terminals --not including food service facilities)

Barber Shops

50 gal/chair

Bars, Cocktail Lounges (Not including food service)

20 gal/seat

Beauty Shops (Style Shops)

125 gal/chair

Bowling Lanes

50 gal/lane

Businesses (other than those listed elsewhere in this table)

25 gal/employee

Camps

Construction or Work Camps

60 gal/person

40 gal/person (with chemical toilets)

Summer Camps

60 gal/person

Campgrounds -- With Comfort Station

(Without water and sewer hookups)

100 gal/campsite

Travel Trailer/Recreational Vehicle Park (With water and sewer hookups)

120 gal/space

Churches (Not including a Kitchen, Food Service Facility, Day Care or Camp)

3 gal/seat

Churches (With a Kitchen but, not including a Food Service Facility, Day Care, or Camp)

5 gal/seat

Country Clubs

20 gal/member

Day Care Facilities

15 gal/person

Factories (Exclusive of industrial waste)

25 gal/person/shift

Add for showers

10 gal/person/shift

Food Service Facilities Restaurants

40 gal/seat or 40 gal/15 ft2 of dining area, whichever is greater

24-hour Restaurant

75 gal/seat

Food Stands

(1) Per 100 square feet of food stand floor space

50 gal

(2) Add per food employee

25 gal

Other Food Service Facilities

5 gal/meal

Hospitals

300 gal/bed

Marinas

10 gal/boat slip

With bathhouse

30 gal/boat slip

Meat Markets

(1) Per 100 square feet of market floor space

50 gal

(2) Add per market employee

25 gal

Motels/Hotels

120 gal/room

With cooking facilities

175 gal/room

Offices (per shift)

25 gal/person

Residential Care Facilities

60 gal/person

Rest Homes and Nursing Homes

With laundry

120 gal/bed

Without laundry

60 gal/bed

Schools

Day Schools

With cafeteria, gym, and showers

15 gal/student

With cafeteria only

12 gal/student

With neither cafeteria nor showers

10 gal/student

Boarding Schools

60 gal/person

Service Stations

250 gal/water closet or urinal

24-hour Service Stations

325 gal/water closet

Stores, Shopping Centers, and Malls (Exclusive of food service and meat markets)

120 gal/1000 ft2 of retail sales area

Stadium, Auditorium, Theater, Drive-in

5 gal/seat or space

Swimming Pools, Spas, and Bathhouses

10 gal/person

(c) An adjusted design daily sewage flow may be granted by the local health department upon a showing as specified in Subparagraphs (c)(1) through (c)(2) that a sewage system is adequate to meet actual daily water consumption from a facility included in Paragraph (b) of this Rule.

(1) Documented data from that facility or a comparable facility justifying a flow rate reduction shall be submitted to the local health department and the State. The submitted data shall consist of at least 12 previous consecutive monthly total water consumption readings and at least 30 consecutive daily water consumption readings. The daily readings shall be taken during a projected normal or above normal sewage flow month. A peaking factor shall be derived by dividing the highest monthly flow as indicated from the 12 monthly readings by the sum of the 30 consecutive daily water consumption readings. The adjusted design daily sewage flow shall be determined by taking the numerical average of the greatest ten percent of the daily readings and multiplying by the peaking factor. Further adjustments shall be made in design sewage flow rate used for sizing nitrification fields and pretreatment systems when the sampled or projected wastewater characteristics exceed those of domestic sewage, such as wastewater from restaurants or meat markets.

(2) An adjusted daily sewage flow rate may be granted contingent upon use of extreme water-conserving fixtures, such as toilets which use 1.6 gallons per flush or less, spring-loaded faucets with flow rates of one gallon per minute or less, and showerheads with flow rates of two gallons per minute or less. The amount of sewage flow rate reduction shall be determined by the local health department and the State based upon the type of fixtures and documentation of the amount of flow reduction to be expected from the proposed facility. Adjusted daily flow rates based upon use of water-conserving fixtures shall apply only to design capacity requirements of dosing and distribution systems and nitrification fields. Minimum pretreatment capacities shall be determined by the design flow rate of Table I of this Rule.

Authority G.S. 130A-335(e);
Eff. July 1, 1982;
Amended Eff. January 1, 1990; January 1, 1984.

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