| (a) The components of an alternative collection system
must be sized based on existing flow data from a system and service
area with similar characteristics, if such data is available. Similar
characteristics for sizing alternative collection systems include:
(1) location;
(2) inflow and infiltration characteristics;
(3) peak flows;
(4) pipe materials;
(5) customer base, including sources of wastewater
and percent contribution from the wastewater sources; and
(6) any other characteristics required by the executive
director.
(b) If flow data from a similar service area with a
conventional collection system is used, the engineering report must
include the expected effects of inflow and infiltration on the peak
flow of the conventional collection system.
(c) Design and construction of an alternative collection
system must minimize excess flows from inflow and infiltration.
(d) Roof drains, street drains, or other types of drains
that allow entrance of stormwater into an alternative collection system
are prohibited.
(e) In the absence of existing data, the sizing of
on-site components in an alternative collection system must be based
on Table B.1. in Figure: 30 TAC §217.32(a)(3) of this title (relating
to Organic Loadings and Flows for New Wastewater Treatment Facilities),
in conjunction with the following equation:
Attached Graphic
(f) Design of the off-site components must be based
on the maximum flow rate expected, calculated using the following
equation:
Attached Graphic
(1) An equivalent dwelling unit (EDU) is assumed to
have an occupancy of 3.5 people. For EDU populations greater than
3.5, the following equation must be used:
Attached Graphic
(2) The safety factor, "B," may be adjusted if higher
wastewater flows are anticipated. A discharge from commercial or institutional
dischargers must be measured directly or calculated under this subsection.
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