15A NCAC 18A .1949       SEWAGE FLOW RATES FOR DESIGN UNITS

(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.

 

History Note:        Authority G.S. 130A‑335(e);

Eff. July 1, 1982;

Amended Eff. January 1, 1990; January 1, 1984.