| (C) The preliminary engineering report may be merged
directly with the final engineering report to produce a single engineering
report at the discretion of the sewerage system owner.
(2) General requirements. The following is required
for each project as applicable.
(A) A brief description of the project with maps showing
the area to be served, general location of proposed improvements,
water and wastewater treatment plant sites, existing and proposed
streets, parks, drainage ditches, creeks, streams, and water mains
shall be provided. The drainage area should be defined clearly, either
by contour map or otherwise. Where a contour map is not available
to the community, one should be obtained and the contours should be
shown at intervals of not more than ten feet. The maps and plans shall
be reproduced on paper not larger than 24 inches by 36 inches in size;
however, where variations are necessary, all sheets shall be uniform
in size.
(B) The domestic population of the area to be served
(present and projected) and design population of the project shall
be included.
(C) The names of industries contributing any significant
wastes, types of industry (standard industry codes), volume of wastes,
characteristics and strength of wastes, population equivalent, and
other pertinent information shall be included. It should be emphasized
that if significant amounts of wastes other than normal domestic sewage
are to be treated at the wastewater treatment plant, sufficient data
on such wastes must be presented to allow an evaluation of the effect
on the treatment process. This would include, but not be limited to,
heavy metals and toxic materials such as polychlorinated biphenyls,
organic chemicals, and pesticides.
(D) The preliminary engineering report shall include
the technical information described in §317.10 of this title
(relating to Appendix B--Overland Flow Process) for all overland flow
projects.
(3) Collection system. The following information shall
be provided in the preliminary engineering report if applicable to
the project:
(A) present area served and future areas to be served;
(B) terrain data in sufficient detail to establish
general topographical features of present and future areas to be served;
(C) lift stations existing and/or proposed;
(D) effect of proposed system expansion on existing
system capacity; and
(E) amount of infiltration/inflow existing and anticipated,
and how it is to be addressed in the collection system design.
(4) Treatment plant. The following information is required
in a preliminary engineering report.
(A) Quantity and quality of existing sewage influent
and changes in the characteristics anticipated in the future. If adequate
records are not available, analyses shall be made for the existing
conditions and such information included in the report.
(B) Design and peak flow rates being considered and
the design period. Design flow is defined as the wet weather maximum
30-day average flow. Therefore, when determining design flow rates,
consideration must be given to flows during periods of wet weather
in order to assure consistent compliance with discharge permit volume
and quality limitations. Peak flow is defined as the highest two hour
flow expected to be encountered under any operational conditions,
including times of high rainfall (generally the two-year, 24-hour
storm is assumed) and prolonged periods of wet weather. For new systems,
the peak flow to average annual flow ratio is normally in the range
of three-five to one, although other peaking factors may be warranted.
(C) Type of treatment plant proposed and the effluent
quality expected. The information should include basis of design,
flow, organic loading, infiltration allowance, and efficiency determinations
sufficient to a given level of treatment.
(D) Type of units proposed and their capacities, considering
the criteria contained herein. The information should include detention
times, surface loadings, weir loadings, flow diagram, and other pertinent
information regarding the design of the plant, including sludge processing
units required for the selected ultimate sludge disposal.
(E) Treatment plant site information and the siting
analysis. The location of the plant, the area included in the plant
site, dedicated buffer zone, and a description of the surrounding
area including a map or a sketch of the area. Particular reference
should be made as to the plant's proximity to present and future housing
developments, industrial sites, prevailing winds, highways and/or
public thoroughfares, water plants, water supply wells, parks, schools,
recreational areas, and shopping centers. If the effluent is to be
discharged to the waters of the state, the immediate receiving stream,
canal, major water course, etc., shall be designated. The siting analysis
shall include:
(i) flood hazard analysis. Provide the 100-year flood
plain elevation. Proposed treatment units which are to be located
within the 100-year flood plain will not be approved for construction
unless protective measures satisfactory to the commission (such as
levees or elevation of the treatment units) are included in the project
design;
(ii) buffer zone analysis. Demonstrate that the location
of each proposed treatment unit is consistent with the buffer zone
criteria specified in Chapter 309 of this title (relating to Domestic
Wastewater Effluent Limitation and Plant Siting).
(5) Sludge management. The preliminary engineering
report shall include a discussion of the method of sludge disposal
to be utilized. The report shall assess the following factors:
(A) estimated quantity of sludge that must be handled
which includes future sludge loads based on flow projections;
(B) quality and sludge treatment requirements for ultimate
disposal;
(C) sludge storage requirements for each alternative
considering normal operating requirements and contingencies;
(D) transportation of sludge;
(E) land use and land availability; and
(F) reliability of the various alternatives, contingencies,
and mitigation plans to ensure reliable capacity and operational flexibility.
(6) Control of bypassing. Information and data shall
be submitted to describe features (auxiliary power, standby and duplicate
units, holding tanks, storm water clarifiers, etc.) and operational
arrangements (flexibility of piping and valves to control flow through
the plant, reliability of power sources, etc.) to prevent unauthorized
discharges of untreated or partially treated wastewater. An outline
of control measures to prevent unauthorized discharges of untreated
or partially treated wastewater during construction (see subsection
(e)(5) of this section) is to be included.
(c) Final engineering design report. The final engineering
design report shall be submitted with the final plans and technical
specifications. The report shall include calculations and any other
engineering information pertaining to the plant design as may be necessary
in the review of the plans and specifications by the commission. The
report must include how the design of the collection system and treatment
plant will handle the potential loss of graywater as defined in TWC, §26.0311.
This report shall bear the signed and dated seal of the registered
professional engineer responsible for the design. Information should
be included to describe any changes that have been made since a preliminary
engineering report was submitted, along with additional information
as follows.
(1) Collection system (if applicable):
(A) minimum and maximum grades proposed for each size
and type of pipe;
(B) lift stations (also refer to §317.3 of this
title (relating to Lift Stations)):
(i) the operating characteristics of the stations at
minimum, maximum, and design flows (both present and future);
(ii) safety considerations, such as ventilation, entrances,
working areas, and prevention of explosions; and
(iii) means of preventing overflow of raw sewage;
(C) capability of existing trunk and interceptor sewers
and lift stations to handle the peak flow under anticipated conditions
and capability of existing treatment facilities to receive and adequately
treat the anticipated peak flows;
(D) type of pipe proposed and its anticipated performance
under the conditions imposed by the particular wastewater quality
and loading conditions;
(E) the manhole spacing proposed;
(F) areas not served by the present proposed project,
and the projected means of providing service to these areas, including
special provisions incorporated in the present plans for future expansion;
(G) amount of infiltration/inflow existing and anticipated,
its hydraulic effect on the proposed and existing system, and an
abatement plan if applicable, including a:
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