| (a) Technical report. Each project shall be accompanied
by a preliminary engineering report outlining the design of the wastewater
application system. The report shall include maps, diagrams, basis
of design, calculations, and other pertinent data as described in
this section.
(1) Location.
(A) Site map. A copy of the United States Geological
Survey 7 1/2 minute topographic map or equivalent for renewals of
the area which indicates the exact boundaries of the application operation
must be included in the technical report. A map from the 7 1/2 minute
series is required if it is published for the site area.
(B) Site drawing. A scale drawing and legal description
of all land which is to be a part of the application operation will
be included in the technical report. The drawing must show the location
of all existing and proposed facilities to include: buildings, wastewater
application or treatment facilities, effluent storage and tail water
control facilities, buffer zones, and water wells. This drawing must
have an index of wells, adjacent property, and other prominent features.
Ownership of land tracts adjacent to the irrigated land shall be shown
on the site drawing and identified by listing legal ownership.
(2) Geology. The existence of any unusual geological
formations such as faults or sink holes on the wastewater application
site shall be noted in the technical report and identified on the
site map. The conceptual design of the wastewater application system
shall include appropriate engineering considerations with respect
to limitations presented by these features.
(3) Soils. A general survey of soils with regard to
standard classifications shall be compiled for all areas of wastewater
application to the soil. Soil surveys compiled by the United States
Department of Agriculture Natural Resources Conservation Service shall
be utilized where available. Conceptual design aspects related to
wastewater application rates, crop systems, seepage, and runoff controls
shall be based upon the soil physical and chemical properties, hydraulic
characteristics, and crop use suitabilities for the wastewater application
site.
(4) Groundwater quality. The technical report shall
fully assess the impact of the wastewater application operation on
the uses of local groundwater resources. In regard to performing this
assessment, the report shall systematically address subparagraphs
(A) and (B) of this paragraph.
(A) All water wells within a 1/2 mile radius of the
application site boundaries shall be located. If available, the water
uses from each well shall be identified. In addition, aspects of construction
such as well logs, casing, yield, static elevation, water quality,
and age shall be furnished and evaluated in the technical report.
Local groundwater resources below the wastewater application site
shall be monitored to establish preoperational baseline groundwater
quality when monitoring wells are available. Monitoring shall provide
the following analytical determination: total dissolved solids, nitrate
nitrogen, chlorides, sulfates, pH, and Escherichia
coli bacteria.
(B) Groundwater resources serving as sources or potential
sources of domestic raw water supply will be protected by limiting
wastewater application rates. Effluent storage and/or treatment ponds
presenting seepage hazards to these groundwater resources shall be
constructed with adequate liners.
(5) Agricultural practice. The technical report shall
describe the crop system proposed for the wastewater application operation.
This description shall include a discussion of the adaptability of
the crop to the particular soil, climatological, and wastewater sensitivity
conditions that will exist at the wastewater application site. Annual
nutrient uptake of the crop system shall be specified, and crop harvesting
frequencies shall be described within the report.
(b) Irrigation. Irrigation application systems utilize
effluent to supply the growth needs of the cover crop.
(1) Secondary effluent. Land application system operators
who use land accessible to the general public shall provide a degree
of treatment equivalent to secondary treatment standards, as required
by §309.3(f)(1) of this title (relating to Application of Effluent
Sets), prior to application of wastewater to land areas.
(2) Primary effluent. Land application systems may
provide for the application of effluent from primary treatment units
provided that the wastewater application system conforms with the
requirements contained in subparagraphs (A) - (E) of this paragraph.
(A) The wastewater application system shall be designed
and operated to prevent a discharge from entering surface water in
the state, and to prevent recharge of groundwater resources which
supply or offer the potential of supplying domestic raw water.
(B) The land application system shall be designed and
operated to achieve application of effluent without adversely affecting
the agricultural productivity of the land application site.
(C) The economic benefits derived from agricultural
operations carried out at the land application site are secondary
to the proper application of wastewater.
(D) The sewerage system owner shall maintain direct
responsibility and control over all aspects of the sewage pretreatment
and application operations, as well as all aspects of any agricultural
activities carried out on the application site.
(E) The land application system shall contain sufficient
area to provide for normal expansion of the facility service area.
In most cases, the application system shall have a design life of
at least 20 years.
(3) Design analysis. The designing engineers shall
utilize a detailed design analysis of limiting hydraulic and nutrient
application rates, and effluent storage needs, as the basis of the
application system design. All projects shall include the detailed
design analysis described in subparagraphs (A) - (C) of this paragraph.
(A) Hydraulic application rate. A water balance study
shall be provided as a part of a detailed application rate analysis
in order to determine the irrigation water requirement, including
a leaching requirement if needed, for the crop system on the wastewater
application areas. The water balance study should generally follow
the example shown in Table 1 in Figure: 30 TAC §309.20(b)(3)(B).
Precipitation inputs to the water balance shall utilize the average
yearly rainfall and the monthly precipitation distribution based on
past rainfall records. The consumptive use requirements (evapotranspiration
losses) of the crop system shall be developed on a monthly basis.
The method of determining the consumptive use requirement shall be
documented as a part of the water balance study. A leaching requirement,
calculated as shown in Table 1 of this subparagraph, shall be included
in the water balance study when the total dissolved solids concentration
of the effluent presents the potential for developing excessive soil
salinity buildup due to the long term operation of the irrigation
system.
(B) Effluent storage. An effluent storage study shall
be performed to determine the necessary storage requirements. The
storage requirements shall be based on a design rainfall year with
a return frequency of at least 25 years (the expected 25 year-one
year rainfall, alternately the highest annual rainfall during the
last 25 years of record may be used) and a normal monthly distribution,
the application rate and cycle, the effluent available on a monthly
basis, and evaporation losses. An example of an effluent storage study
is shown in Table 3 in Figure: 30 TAC §309.20(b)(3)(B).
Attached Graphic
(C) Nitrogen application rate. Irrigation shall be
limited to prevent excessive nitrogen application. The annual liquid
loading shall not exceed that which would introduce more nitrogen
than is annually required by the crop plus 20% volatilization. Values
of crop nitrogen requirements shall be justified in the design report.
The application rate shall be calculated by the formula in Figure:
30 TAC §309.20(b)(3)(C).
Attached Graphic
(4) Soil testing. Representative soil samples shall
be taken from the root zones of wastewater application sites to establish
preoperational soil concentrations of pH, total nitrogen, potassium,
phosphorus, and conductivity. Sampling procedures shall employ accepted
techniques of soil science for obtaining representative analytical
results. Preoperational soil concentration of the parameters listed
in this paragraph shall be furnished in the technical report. The
project development shall provide for a minimum of one soil test annually
from each wastewater application site for the duration of the application
system design life.
(5) Standard irrigation best management practices.
(A) Screening devices should be installed on all lift
pump suction intakes.
(B) The design of sprinkler irrigation systems should
allow operational flexibility and efficiency and ease of maintenance.
(i) The system should be designed to provide a uniform
water distribution.
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