ottawa county sewer district wastewater rules and regulations for ...

disconnection shall occur no earlier than thirty (30) days after service of
a written notice of disconnection.
INFILTRATION AND INFLOW
TABLE “A”
Calculation for Infiltration/Inflow:
Since Ohio EPA uses 400 gallons per day per equivalent dwelling unit (EDU) as a
design standard and Ottawa County uses the Ohio EPA standard as a basis for current
billing, the SSES Policy was correlated with this standard while using the U.S. EPA
handbook Sewer System Infrastructure Analysis and Rehabilitation and the American
Society of Civil Engineers’ Existing Sewer Evaluation and Rehabilitation, WEF Manual
of Practice FD-6, ASCE Manuals and Reports on Engineering Practice No. 62, second
edition, as additional resources.
The Ohio EPA Standard is based on 100 gallons per capita day (gpcd) usage and four
(4) people per family or 400 gpd/EDU. The Ohio EPA 100 gpcd standard could be
further allocated as 80 gpcd for domestic flow and 20 gpcd as infiltration based on U.S.
EPA criteria.
The ASCE’s Exiting Sewer Evaluation and Rehabilitation, Existing Sewer Evaluation
and Rehabilitation, WEF Manual of Practice FD-6, ASCE Manuals and Reports on
Engineering Practice No. 62, second edition, states, “Even in a well constructed,
separated system, the ratio of wet maximum to dry average usually ranges from 2 to 3
and wet peak to dry average from 3 to 4; higher values indicated a more pronounced
problem.
A. Ohio EPA EDU = 400 gpd (based on 100 gpcd)
= 320 gpd (based on 80 gpcd domestic flow)
= Wet Max = 3 x 320 = 960 gpd/EDU
= Wet Peak = 4 x 320 = 1,280 gpd/EDU
Summary
1. The highest wet maximum flow would be 960 gpd per EDU. Under no
circumstances will the acceptable wet maximum flow exceed this amount.
2. The highest wet peak flow would be 1,280 gpd per EDU divided by 1440 minutes =
0.889 gpm. Under no circumstances will the acceptable wet peak flow rate exceed
this amount.