| (ii) to maintain sufficient volume to contain rainfall
and rainfall runoff from the design rainfall event without overflow.
The depth for this volume must be at least one vertical foot allocated
within the RCS above the volume required in clause (i) of this subparagraph.
(f) Dewatering system. An irrigation system or other
liquid removal system used by an AFO must be designed to ensure that
the system is capable of dewatering the RCSs on a regular schedule.
RCSs shall be equipped with irrigation or wastewater removal systems
capable of dewatering the RCSs whenever needed to restore the operating
capacity. Dewatering equipment shall be maintained in proper working
order.
(g) RCS embankment and liner design.
(1) For RCSs where the depth of water impounded against
the embankment at the spillway elevation is three feet or more, the
RCS is considered to be designed with an embankment. The pollution
prevention plan shall include a description of the design specifications
for the RCS embankments. The following design specifications are required
for all new construction or the modified portions of existing RCSs.
(A) Soils used in the embankment shall be free of foreign
material such as rocks larger than four inches, trash, brush, and
fallen trees.
(B) The embankment shall be constructed in lifts or
layers no more than eight inches compacted to six inches thick at
a minimum compaction effort of 95% Standard Proctor Density (ASTM
D698) at -1% to +3% optimum moisture content.
(C) All embankment walls shall be stabilized to prevent
erosion or deterioration.
(D) Embankment construction must be accompanied by
certified compaction tests including in-place density and moisture
in accordance with ASTM D1556, D2167, or D2937 for density and D2216,
D4634, D4944, or D4959 for moisture, and D2922-91 or D6938-07 for
moisture and density, or equivalent testing standards.
(E) Additional protection for new or modified portions
of existing RCSs that are constructed with embankments designed to
contain runoff from a drainage area shall be constructed with a spillway
or other outflow device properly sized according to NRCS design and
specifications to protect the integrity of the embankment.
(F) For all new construction or the modified portions
of existing RCSs, each RCS must have a minimum of two vertical feet
of freeboard constructed with materials equivalent to those used at
the time of design and construction between the top of the embankment
and the structure's spillway. RCSs without spillways must have a minimum
of two vertical feet of freeboard between the top of the embankment
and the required storage capacity.
(2) For all new construction and for all structural
modifications of existing RCSs, each RCS must meet the requirements
for lack of hydrologic connection or have a liner consistent with
subparagraph (B), (C), or (D) of this paragraph.
(A) This subparagraph applies to lack of hydrologic
connection requirements. Documentation must show that there will be
no significant leakage from the RCS; or that any leakage from the
RCS will not migrate to water in the state. A permit or authorization
will require documentation of the lack of hydrologic connection certified
by a licensed Texas professional engineer or licensed Texas professional
geoscientist and must include information on the hydraulic conductivity
and thickness of the natural materials underlying and forming the
walls of the containment structure up to the wetted perimeter. If
it is claimed that no significant leakage would result from the use
of in-situ materials, documentation
must be provided that leakage will not migrate to waters in the state.
The operator must at a minimum include maps showing groundwater flow
paths, or that the leakage enters a confined environment. A permit
or authorization will require a written determination by an NRCS engineer,
a licensed Texas professional engineer or a licensed Texas professional
geoscientist that a liner is not needed to prevent a significant hydrologic
connection between the contained wastewater and waters in the state.
(B) This subparagraph applies to RCS liners using in-situ material. In-situ
material is undisturbed, in-place, native soil material. In-situ materials must at least meet the
minimum criteria for hydraulic conductivity, thickness, and calculated
specific discharge, as described in subparagraph (C) of this paragraph.
Samples shall be collected and analyzed in accordance with subparagraph
(E) of this paragraph. This documentation must be certified by a licensed
Texas professional engineer or licensed Texas professional geoscientist.
(C) This subparagraph applies to constructed or installed
earthen liners. Constructed or installed liners must be designed by
a licensed Texas professional engineer. The liner must be constructed
in accordance with the design and certified as such by a licensed
Texas professional engineer. Compaction tests and post construction
sampling and analyses will provide support for the liner certification.
Liners shall be designed and constructed to have hydraulic conductivities
no greater than 1 x 10-7 centimeters per second (cm/sec), with a thickness
of 1.5 feet or greater or its equivalency in other materials, and
not to exceed a specific discharge through the liner of 1.1 x 10-6
cm/sec calculated using Darcy's Law with the water level at the spillway
depth. Constructed or installed liners must be designed and constructed
to meet the soil requirements, lift requirements, and compaction testing
requirements identified in the permit or authorization. The operator
shall maintain the liner to minimize the percolation of wastewater
through the liner.
(D) This subparagraph applies to geosynthetic liners.
Geosynthetic liners that meet the specific discharge requirements
in subparagraph (C) of this paragraph are acceptable if certified
by a licensed Texas professional engineer. Documentation must be presented
to the executive director for review and approval before putting into
service. Installation of the liner shall be certified by a licensed
professional engineer that the liner and subgrade were completed according
to the manufacturer's recommendations and current standards. Seams
shall be completed in accordance with the manufacturer's requirement.
When wedge weld seams are used, non-destructive seam testing shall
be conducted on the complete length of the wedge weld by standard
air pressure testing. The certification must document compliance with
all of the following standards: ASTM D5888 Storage and Handling of
Geosynthetic Clay Liners, ASTM D5889 Quality Control of Geosynthetic
Clay Liners, and ASTM D6102 Guide for Installation of Geosynthetic
Clay Liners.
(E) This subparagraph applies to liner sampling and
analyses of in-situ material and earthen
liners.
(i) The licensed Texas professional engineer or licensed
Texas professional geoscientist shall use best professional practices
to ensure that corings or other liner samples will be appropriately
plugged with material that also meets liner requirements of this subsection.
(ii) Samples shall be collected in accordance with
ASTM D1587 or other method approved by the executive director. For
each RCS, a minimum of two core samples collected from the bottom
of the RCS and a minimum of at least one core sample from each sidewall.
Additional samples may be necessary based on the best professional
judgment of the licensed professional engineer. Distribution of the
samples shall be representative of liner characteristics, and proportional
to the surface area of the sidewalls and floor. Documentation shall
be provided identifying the sample locations with respect to the RCS
liner.
(iii) For earthen liners, undisturbed samples shall
be analyzed for hydraulic conductivity in accordance with ASTM D5084,
whole pond seepage analysis as described in ASABE Paper Number 034130,
Double Ring Infiltrometer (stand pipe), or other method approved by
the executive director.
(F) A permit or authorization shall include provisions
whereby the executive director may, upon written notice, require the
operator to install a leak detection system or monitoring well(s),
based upon a determination that significant potential exists for the
contamination of water in the state or drinking water.
(G) Documentation of lack of hydrologic connection,
liner, and capacity certifications by a licensed Texas professional
engineer or licensed Texas professional geoscientist must be completed
for each RCS and kept on site.
(h) Manure storage. The AFO operator shall provide
manure storage capacity based upon manure and waste production, land
availability, and the NRCS Field Office Technical Guide or equivalent
standards. When manure is stockpiled, it shall be stored in a well-drained
area with no ponding of water, and the top and sides of stockpiles
shall be adequately sloped to ensure proper drainage. Runoff from
manure storage piles must be retained on site. If the manure areas
are not roofed or covered with impermeable material, protected from
external rainfall, or bermed to protect from runoff in the case of
the design rainfall event, the manure areas must be located within
the drainage area of the RCS and accounted for in the design calculations
of the RCS.
|
| Source Note: The provisions of this §321.38 adopted to be effective April 1, 1987, 12 TexReg 904; amended to be effective September 18, 1998, 23 TexReg 9354; amended to be effective July 15, 2004, 29 TexReg 6652; amended to be effective July 31, 2014, 39 TexReg 5786 |
