Current through Register Vol. 48, No. 38, September 20, 2024
a) Type of
Treatment
1) As a minimum, the following
items shall be considered in the selection of the type of treatment:
A) Present and future effluent
requirements.
B) Location and local
topography of the plant site.
C)
The effects of industrial wastes likely to be encountered.
D) Ultimate disposal of sludge.
E) System capital costs.
F) System operating and maintenance costs and
basic energy requirements.
G)
Existing unit process performance and capacity.
H) Process complexity governing operating
personnel requirements.
I)
Environmental impact on present and future adjacent land use.
2) The plant design shall provide
the necessary flexibility to perform satisfactorily within the expected range
of waste characteristics and volumes.
b) Required Engineering Data for New Process
Evaluation
1) The policy of the Agency is to
encourage rather than obstruct the development of any methods or equipment for
treatment of wastewaters. The lack of inclusion in these standards of some
types of wastewater treatment processes or equipment should not be construed as
precluding their use. The Agency may approve other types of wastewater
treatment processes and equipment under the condition that the operational
reliability and effectiveness of the process or device shall have been
demonstrated with a suitably-sized prototype unit operating at its design load
conditions, to the extent required.
2) To determine that such new processes and
equipment have a reasonable and substantial chance of success, the Agency will
require the following:
A) Monitoring
observations, including test results and engineering evaluations, demonstrating
the efficiency of such processes.
B) Detailed description of the test
methods.
C) Testing, including
appropriately-composited samples, under various ranges of strength and flow
rates (including diurnal variations) and waste temperatures over a sufficient
length of time to demonstrate performance under climatic and other conditions
which may be encountered in the area of the proposed installations.
D) Other appropriate information.
3) The Agency will require that
appropriate testing be conducted and evaluations be made under the supervision
of a competent process engineer other than those employed by the manufacturer
or developer.
c) Design
Loads
1) Hydraulic Design
A) New Systems
Plans for sewage treatment plants to serve new sewer systems
for municipalities or sewer districts shall be based upon a design average
daily flow of at least 100 gallons per capita, to which must be added
industrial waste volumes. The design also shall include appropriate allowance
for flow conditions determined under Section 370.122.
B) Existing Systems
Where there is an existing sewer system, the volume and rates
of the existing sewage flows shall be determined. The determination shall
include both dry weather and wet weather flows. At least one year's flow data
should be used to determine the design flows that are defined in Section
370.220.
C) Treatment Plant Design Capacity
The treatment plant capacity shall be rated on the design
average flow, selected after any sewer system rehabilitation, plus appropriate
future growth. The design of treatment units that are not subject to peak flow
requirements shall be based on the design average flow. For plants subject to
high wet weather flows or overflow detention pumpback flows, the design maximum
flow that the plant is to treat on a sustained basis must be specified.
2) Organic Design
A) New Systems Minimum Design
i) Domestic waste treatment design shall be
on the basis of at least 0.17 pounds of biochemical oxygen demand (BOD5) per
capita per day and 0.20 pounds of suspended solids per capita per
day.
ii) When garbage grinders are
used in areas tributary to a domestic treatment plant, the design basis should
be increased to 0.22 pounds of BOD5 and 0.25 pounds of suspended solids per
capita per day.
iii) Domestic waste
treatment plants that will receive industrial wastewater flows shall be
designed to include these industrial waste loads.
B) Existing Systems
When an existing treatment works is to be upgraded or
expanded, organic design shall be based upon the actual strength of the
wastewater as determined from measurements taken in accordance with subsection
(c)(1)(B), with an appropriate increment for growth as determined under the
provisions of subsection (c)(2)(A).
3) Shock Effects
Domestic waste treatment designs shall consider and take into
account the shock effect of high concentrations and diurnal peaks for short
periods on the treatment process, particularly for small waste treatment plants
serving institutions, restaurants, schools, etc.
4) Design by Analogy
Data from similar existing systems may be utilized in the
case of new systems; however, thorough investigation and adequate documentation
shall be made to establish the reliability and applicability of such
data.
d)
Conduits
1) All piping and channels shall be
designed to carry the maximum expected flows. The incoming sewer shall be
designed for unrestricted flow. Bottom corners of the channels must be
filleted. Conduits shall be designed to avoid creation of pockets and corners
where solids can accumulate.
2)
Suitable gates should be placed in channels to seal off unused sections which
might accumulate solids. The use of shear gates is permitted where they can be
used in place of gate valves or sluice gates. Non-corrodible materials shall be
used for these control gates.
e) Arrangement of Units
Component parts of the plant should be arranged for greatest
operating convenience, flexibility, economy, continuity of maximum effluent
quality, and so as to facilitate installation of future units.
f) Flow Division Control
Flow division control facilities shall be provided as
necessary to insure organic and hydraulic loading control to plant process
units and shall be designed for easy operator access, change, observation, and
maintenance. The use of head boxes equipped with sharp-crested weirs or similar
devices are recommended. The use of valves for flow splitting is not
acceptable. Appropriate flow measurement shall be incorporated in the flow
division control design.
g)
Load Equalization and Attenuation
1)
Equalization of hydraulic and organic loads to downstream treatment units is
recommended where the peak hourly load exceeds 300% of the design average load.
Particular attention shall be given to equalization of pumped flows to limit
hydraulic surges on downstream units.
2) Plants proposed to receive sewage wastes
from only institutions (motels, schools, hospitals, nursing homes, etc.) or
industries which discharge substantially the total flow in 12 hours or less,
shall be designed to include flow equalization. Where flow equalization
facilities are provided, the design shall include adequate aeration and mixing
equipment to prevent septicity.
