SOIL CONSERVATION SERVICE

Document Sample
SOIL CONSERVATION SERVICE Powered By Docstoc
					                                                                                                          398 - 1


                        NATURAL RESOURCES CONSERVATION SERVICE
                                CONSERVATION PRACTICE STANDARD


                                     FISH RACEWAY OR TANK
                                                                   3
                                                     (Ft. and Ft. )


                                                      CODE 398



DEFINITION                                                             through the tank center by means of a
                                                                       standpipe or bottom drain.
A channel or tank with a continuous flow of
water constructed or used for high-density fish                   The raceway dimensions shall be designed
production.                                                       based upon the available water and planned
                                                                  production level.
PURPOSE
                                                                  Water Requirements
   To provide a facility containing flowing
    water of suitable temperature and quality                     Quantity – A water supply of sufficient volume
    for dependable production of fish;                            must be available for the species being
                                                                  produced either by gravity flow or by pumping.
   To manipulate chemical, physical, and                         Generally, this amount would equate to two
    biological factors to enhance fish                            complete water exchanges per hour for a
    production;                                                   raceway length of 80 to 100 ft. The water
   To maintain water quality.                                    volume shall be measured during periods of
                                                                  low flow.
CONDITIONS WHERE PRACTICE APPLIES                                 Quality – Water must be free of harmful
This standard applies to raceways or tanks that                   gases, minerals, silt, pesticides, and other
conduct flowing water to produce fish. It                         contaminants. A water analysis shall be made
applies to earthen channels as well as those                      before design and construction unless previous
channels and tanks constructed of concrete,                       use or experience indicates the quality is
concrete block, timber, rock, fiberglass, or                      satisfactory for the desired species. An
other materials.                                                  example of water quality requirements for trout
                                                                  and catfish are shown in Table 1. Uniquely
CRITERIA                                                          different water quality parameters may be
                                                                  applicable to other species.
General Criteria Applicable to All Purposes
The facility must be designed to provide
protection from flooding, sedimentation, and
contamination by pollutants from outside
sources.
Construction of fish raceways are generally
1. linear channels where water flows in at one
   end and exits at the other end, or
2. circular, rectangular, or oval tanks where
   water enters through nozzles or jets in a
   manner that creates a rotary circulation
   within the tank and discharge typically is


Conservation practice standards are reviewed periodically and updated if needed. To obtain      NRCS, NHCP
the current version of this standard, contact your Natural Resources Conservation Service
State Office or visit the Field Office Technical Guide.                                      September 2009
398 - 2


                                                            practice, use the same or similar species to
                                                            those in the surrounding area to help minimize
     Table 1. Water quality requirements                    any visual or aesthetic disruption.
                                          Species           Adequate provisions must be made to protect
     Quality parameter            Trout          Catfish    earth surfaces from wave erosion. Install
                                                            fences as necessary to exclude human,
  Dissolved       Desirable     8 ppm or >     5 ppm or >
                                                            animal, and vehicle traffic to allow for and
   oxygen         Minimum         5 ppm          3 ppm
                                                            maintain the establishment of vegetation and
 Temperature      Desirable      55 – 64         75 – 84    for safety considerations Road surfaces along
    (ºF)          Min./Max.      45 / 70         70 / 90    raceways and the outer perimeter of tanks
                  Desirable      6.5 – 9.0      6.5 – 9.0   shall be treated as needed to provide access
      pH                                                    and reduce erosion. Dikes and levees should
                  Min./Max.      6.0 / 9.5      6.0 / 9.5
                                                            be crowned to provide drainage.
    Carbon       Desirable      2 ppm or <     5 ppm or <
    dioxide      Min.*/Max.      0 / 3 ppm     0 / 10 ppm
                                                            Criteria for Linear Channel Raceways
 *Toxicity varies with dissolved oxygen concentration,
                                                            Channel raceways are generally of two types:
 temperature and pH.
                                                              Concrete or concrete block construction.
                                                              Designed and construct raceways in
Predators. Fences, screens, nets, wires, or
                                                              accordance with current American Concrete
other materials shall be provided as needed to                Institute (ACI). Codes for Structural Concrete
prevent the loss of fish to predators. Traps or               or Concrete Masonry. Where concrete or
other devices that are potentially harmful for                concrete block raceways are installed, the
humans, livestock, or pets shall be placed only               bulkheads or check dams must be of the
in secure locations not normally accessible                   same specification.
except through special effort. A license or
permit from the appropriate state agency may                  Earthen channels constructed with a
be required to perform such activities.                       trapezoidal or parabolic cross section.
                                                              Construct raceways with a trapezoidal or
Waste treatment. Plans for treatment,
                                                              parabolic cross section. Bottom widths
storage, or use of waste generated or caused                  depend on the volume of water available but
by the operation of fish raceways or tanks shall              shall be no less than 4 ft. Side slopes shall
be developed and made a part of the design                    be 1:1 or flatter depending on a saturated
and installation of the practice. Such                        soil slope stability analysis. Side slopes and
components may include the construction of                    bottoms of raceways must be smooth and
waste storage ponds (425), storage structures                 uniform to minimize dead water areas.
(313), treatment lagoons (359), settling basins,
or other facilities. Waste utilization (633) by             Grade. Wherever possible, design and
the spreading of waste on land through                      construct raceways with a minimum bottom
irrigation or hauling is permissible if soils and           grade of 0.5 ft. per 100 ft. The raceway outlet
land resources are available according to a                 will control the water surface grade.
Nutrient Management Plan. Discharges into                   Length. The maximum length of each
streams must meet state standards for the                   raceway section is determined by site
stream, based on size of the operation, and                 topography and need for re-aeration of the
comply with National Pollutant Discharge                    water but should not exceed 100 ft. Depending
Elimination System (NPDES) regulations.                     on water volume and quality, raceway sections
Protection. A protective cover of vegetation                may be constructed in series by installing a
shall be established on all exposed surfaces                bulkhead or check dam at the lower end of
that have been disturbed. If soil or climatic               each section.
conditions preclude the use of vegetation,                  Width. The width of individual raceways shall
other methods may be used for protection                    be selected considering the available water
(Critical Area Planting – 342). When                        supply, harvesting equipment and operating
revegetating the earthen components of this                 and maintenance needs of the system.

NRCS, NHCP
September 2009
                                                                                               398 - 3


Freeboard. The minimum difference in                bulkhead between sections and at the exit end
elevation between the water surface in the          to prevent loss of fish. They shall be placed at
raceway and the top of the bulkhead, dike, or       least 6 to 8 in. upstream from the flashboards
levee alongside the raceway is 0.5 ft.              and shall extend at least 6 to 8 in. above the
                                                    expected water level to prevent fish from
Dikes and levees. The minimum top width of
                                                    escaping by jumping. Openings for screens
an earthen dike or levee shall be 6 ft. Side
                                                    shall be designed considering the size range of
slopes of earthen dikes and levees above the
                                                    fish to be separated. The water velocity
designed water surface shall be 2:1 or flatter.
                                                    through screens shall be slow enough to
When the top of the dike or levee is to be used
                                                    prevent impinging of fish against the screen.
for a road, the minimum top width shall be 14
ft. with at least 3:1 side slopes.                  Aeration. Each bulkhead shall be fitted with a
                                                    weir overfall. Flashboards in the opening or
Bulkheads. Structural or earthen barriers
                                                    throat section of the bulkhead may be used for
called bulkheads are to be placed across
                                                    this purpose. The width of the weir or weirs
raceway channels to create shorter sections, to
                                                    should be equal to the bottom width of the
establish and maintain the desired water levels,
                                                    raceway but shall not be less than 4 ft. where
and to provide aeration of the water. In
                                                    flashboards are used to establish the desired
addition to serving as a barrier, they shall have
                                                    water level. Two or more weirs separated by
an opening or throat section that allows
                                                    rigid center sections shall be installed when the
complete drainage to the bottom of the
                                                    width of the raceway exceeds 8 ft. To increase
raceway channel unless other drainage
                                                    aeration as part of the design, arrange a splash
facilities are provided. Bulkheads may be
                                                    board or series of boards to create successive
constructed of earth, concrete, concrete block,
                                                    splashes or place nozzles in the tank above the
rock masonry, steel or other durable metal,
                                                    water surface. The minimum distance from the
treated timber, or a combination of these.
                                                    weir crest to the water level below should be no
Earthen bulkheads are to have a minimum top
                                                    less than 1 ft.
width of 4 ft. and side slopes of 2:1 or flatter.
Structural bulkheads used in earthen raceways
                                                    Criteria for Tank Raceways
must extend at least 24 in. into the sides and
bottom of the channel. Concrete bulkheads           Tank raceways are circular, rectangular, or
shall have a minimum top width of 6 in. and a       oval and are constructed of concrete, metal,
minimum bottom width of 8 in. Openings and          fiberglass, or other suitable material.
cores in concrete blocks shall be filled with       Fiberglass and a variety of similar materials
either concrete or mortar mix. The opening or       commonly referred to as "plastic" tanks are
throat section of bulkheads may be constructed      generally suitable if construction and support
of concrete, concrete block, wood, or metal. It     are sufficient to provide strength and durability.
shall have slots or grooves along the vertical      Noncircular tanks must have an interior
face that allow flashboards and screens to be       dividing wall to obtain proper circulation.
installed.                                          Construct tank raceways shall be constructed
                                                    at locations accessible to water supplies,
Drains. A pipe drain with minimum diameter          management personnel, and feed and harvest
of 6 in shall be provided at the bottom of the      equipment.
bulkhead unless flashboards used to establish
the desired water level can be removed to           Water supply. Water inlets to the tank may be
provide complete drainage. Where possible,          through jets or nozzles or similar devices that
each unit in a series should be constructed so      provide a tangential force to the water in the
that it can be drained independently of the         tank. Submerged nozzles should not be near
other units.                                        the bottom because of the problem of uplift of
                                                    waste particles. The nozzles shall be
Screens. Screens shall be provided at the           positioned so that flow in the tank is
inlet of the system if necessary to exclude wild    counterclockwise to take advantage of the
fish. Screens shall also be placed at each


                                                                                    NRCS, NHCP
                                                                                September 2009
398 - 4


natural tendency for water in North America to       Impacts of cultivated non-native fish on
rotate in this direction.                             endemic fish populations.
Waste removal. Incorporate provisions for            Existence of cultural resources in the
waste removal shall be incorporated in the            project area and any project impacts on
design. Bottom troughs, screens, or center-           such areas.
positioned drain pipe shall be provided as part
                                                     Conservation and stabilization of any
of the tank construction.
                                                      existing archeological, historic, structural,
                                                      and traditional cultural properties.
CONSIDERATIONS
Consider the effect on:                           PLANS AND SPECIFICATIONS
   Water budget, especially on volumes and       Plans and specifications are to be prepared for
    rates of runoff, infiltration, evaporation,   specific field sites and include construction
    transpiration, deep percolation, and ground   plans, drawings, job sheets, construction
    water recharge.                               specifications, narrative statements in
                                                  conservation plans, or other similar
   Downstream flows and aquifers that could
                                                  documents. These documents are to specify
    affect other water uses.
                                                  the requirements for installing the practice,
   Volume of downstream flow that might          such as the kind, amount, or quality of
    cause undesirable environmental, social,      materials to be used, or the timing or sequence
    or economic effects.                          of installation activities including site-specific
                                                  construction details.
   Visual quality of downstream water
    resource.
                                                  OPERATION AND MAINTENANCE
   Short-term and construction-related effects
                                                  Prepare an operation and maintenance plan
    on the quality of the onsite and
                                                  shall be prepared that provides for inspection,
    downstream water.
                                                  operation, and maintenance of vegetation,
   Movement of dissolved organic and             pipes, valves, raceways, tanks, dikes, levees,
    inorganic chemicals downstream and            bulkheads, filtration, and other parts of the
    towards ground water recharge areas.          system.
   Wetlands, riparian areas and water-related
    wildlife habitats.




NRCS, NHCP
September 2009

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:0
posted:10/1/2012
language:Unknown
pages:4