250 R.I. Code R. 250-RICR-150-10-6.22

Current through December 26, 2024

Section 250-RICR-150-10-6.22 - Wastewater Flow

A. Determination of Wastewater Flow

1. An OWTS must be designed to dispose of the estimated maximum daily flow from the building(s) it serves. The maximum daily flow is estimated by multiplying flow per unit from § 6.22(B) of this Part by the maximum design capacity of the building. For facilities with more than one (1) use listed in § 6.22(B) (e.g., a retail store with a restaurant), the maximum daily flow for the facility shall be the total of the flows from the separate uses using § 6.22(B). The employee contribution to the design flow shall be included for non-residential uses other than restaurants by estimating the maximum number of employees who may be present during a single day of operation multiplied by a design flow of fifteen (15) gallons per person per day.

2. For establishments not listed in § 6.22(B) of this Part, the maximum daily flow shall be determined by either of the following:

a. Two (2) times the average daily meter reading taken from a minimum of two (2) comparable establishments for one (1) month during the period of the year that represents the greatest water use for the establishment; or

b. If six (6) months of daily meter readings are available for a minimum of two (2) comparable establishments that includes the period of the year that represents the greatest water use for the establishment, the OWTS shall be designed using the highest daily flow without the use of a peaking factor.

B. Wastewater Design Flows

TYPE OF USE	UNIT	GALLONS PER DAY
RESIDENTIAL [Minimum design flow for residential use shall be three hundred forty-five (345) gallons per day (three (3) bedrooms), unless otherwise permitted in accordance with § 6.22(D) of this Part.]
Single family residence	per bedroom (2 persons per bedroom)	115
Multiple family residence	per bedroom (2 persons per bedroom)	115
INSTITUTIONAL
Assisted living facility	per bedroom (2 persons per bedroom)	115
Church	per seat	1
Church hall (fellowship hall)	per seat	5
Hospital	per bed	150
Library	per visitor	5
Nursing home/rest home	per bed	125
Group home	per bed	200
Correctional, rehabilitation facility	per bed	100
Gymnasium	per seat	3
Gymnasium	per participant	15
Highway rest stop	per person	5
Public park with toilets	per person	5
add for showers	per person	10
CAMPS AND CAMPGROUNDS
Day camp	per person	15
add for mess hall	per person/meal	3
Camp - overnight	per person	25
add for mess hall	per person/meal	3
Campground with washroom and toilets	per site	50
Recreational vehicle park with water service	per site	100
Add for central dining facilities	per seat	35
Recreational vehicle park without water service	per site	50
Add for central dining facilities	per seat	35
Add for central washroom and toilet facilities	per site	50
SCHOOLS
School	per person	10
add for cafeteria	per person	5
add for gymnasium and showers	per person	10
Boarding school, college	per person	50
Day care center	per person	10
RESTAURANTS [Minimum design flow for restaurants shall be 500 gallons per day.]
Restaurant	per seat	40
Restaurant - with singleservice articles
with public restrooms	per seat	25
without public restrooms	per seat	20
add for drive-up window	500
Lounge, bar (no food service at that seat)	per seat	10
Banquet hall	per seat	5
Ice cream parlor, take out service only	per store	500
COMMERCIAL [Minimum design flow for commercial use shall be 100 gallons per day]
Auto service station	per pump	25
per repair bay	100
Barber shop/Beauty salon	per chair	50
add for sink	per hair care sink	200
Bed & Breakfast	per bedroom	110
Bowling alley	per alley	100
Catering kitchen, no food service on-site	per meal prepared	3
Country club
dining room	per seat	40
snack bar/lounge	per seat	20
lockers and showers	per locker	20
Doctors /Chiropractor/ Therapist office	per doctor/chiropractor/therapist	250
Dog/Pet grooming	per station	500
Dentist office	per chair	200
Drive-in theater	per vehicle stall	5
Factory/Industrial plant	per person	15
add for cafeteria	per person	5
Food store < 5,000 square feet (See Note 1)	per store	350
add for deli flow	per store	100
add for bakery flow	per store	100
add for meat dept. flow	per store	150
add for fish market flow	per store	150
add for public restrooms	per store	200
Food store > 5,000 square feet (See Note 1)	per store	700
add	per square foot > 5,000 sq ft	0.05
add for deli flow	per store	200
add for bakery flow	per store	200
add for meat dept. flow	per store	300
add for fish market flow	per store	300
add for public restrooms	per store	400
Funeral home	per parlor	500
Hotel, motel	per unit	100
With efficiency units	per unit	150
Health club	per participant	15
Kennel	per kennel	10
Marina (shore-side facilities)	per slip	10
add for showers	per slip	10
Mobile home park/Manufactured home park	per site	230
Office building	per employee	15
Retail store	per employee	15
Rooming house/Boarding house	per bedroom	80
Self-Service Laundry (See Note 2)	per machine	500
Shopping center/Strip mall/Multi-use retail Calculate on the largest of either: a) The total flow for the uses within as determined from this table, or b) Per square foot	per square foot	0.1
Skating rink	per seat	3
Swimming pool	per person	15
Tennis court - outdoor	per court	100
Tennis court - indoor	per court	400
Theater, auditorium	per seat	3
Veterinary office	per veterinarian	200
Notes: (1) The design flow for a stand alone deli, bakery, meat store or fish market will be three hundred fifty (350) gallons per day if the facility is less than five thousand (5,000) square feet or seven hundred (700) gallons per day if the facility is five thousand (5,000) square feet or more. (2) Self-Service laundry OWTS designs must include pretreatment to remove lint from the wastewater.

C. Determining the Number of Bedrooms in a Single Family Residential Dwelling - For purposes of aiding the planning, designing, building, renovation, remodeling or expansion of residential dwellings, the following guidelines shall be used in determining the number of bedrooms. These guidelines are presented in acknowledgement that, in many cases, houses contain rooms meeting the strict definition of bedroom as defined in these Rules, but which are not intended to be nor will be used as bedrooms.

1. No residence served by an OWTS shall be allowed to have more bedrooms than is permitted under the Department-issued permit for the OWTS serving the dwelling. A dwelling exceeding the number of bedrooms provided for in the permit shall be in violation of these Rules.

2. In determining the number of bedrooms contained in any residence, it shall be presumed that all residences contain a living room, a kitchen, a bathroom and at least one (1) bedroom.

3. For OWTSs installed without State approval, OWTSs installed prior to April 9, 1968 and cesspools, the determination on number of bedrooms shall be based on the consideration of municipal records, floor plans and the guidelines herein. In the case of a one (1) bedroom residence, the determination shall be based on municipal records.

4. When a determination of the number of bedrooms shall be based on total number of rooms, § 6.22(D) of this Part shall be used. Foyers, closets, bathrooms and rooms without windows are not counted as rooms in § 6.22(D). Functionally combined kitchens/dining rooms and living/dining rooms greater than three hundred (300) square feet shall be counted as two (2) rooms. § 6.22(D) of this Part may be used by applicants for any OWTS application to the Department.

D. Determination of Number of Bedrooms

Total Number of Rooms	Assumed Number of Bedrooms
5 or less	2
6-7	3
8-10	4
11-12	5
13 or more	6

The Director may permit the filing of a deed restriction by which an applicant may self-restrict the use of a residence to one (1) less bedroom than may be determined in accordance with § 6.22(D) of this Part. In no case shall the deed restriction be for less than two (2) bedrooms. The Director may consider the gross square footage of a residence as a factor against granting a bedroom restriction by deed.

E. Separate OWTSs - Where residential uses need to install separate OWTSs, the following proportions of the total flow shall be used unless there is definite data available as to the exact distribution of flow: blackwater forty percent (40%) and graywater sixty percent (60%). If a separate system is used for laundry wastes, it shall be designed on twenty percent (20%) of the total flow.

F. Misrepresented Applications - An OWTS Application that has been approved but later shown to contain faulty or misrepresented information shall not, in and of itself, be used to determine the number of bedrooms in a residential dwelling or the design flow for a non-residential structure.

250 R.I. Code R. 250-RICR-150-10-6.22

Amended effective 11/25/2018
Amended effective 12/28/2021
Amended effective 7/1/2022