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NRCS reviews and periodically updates conservation practice standards. To obtain the current 

version of this standard, contact your Natural Resources Conservation Service State office or 

visit the Field Office Technical Guide online by going to the NRCS website at 

https://www.nrcs.usda.gov/ and type FOTG in the search field. 

USDA is an equal opportunity provider, employer, and lender.

Natural Resources Conservation Service 

CONSERVATION PRACTICE STANDARD 

IRRIGATION PIPELINE 

CODE 430 

(ft)

DEFINITION 

A pipeline and appurtenances installed to convey water for storage or application as part of an irrigation

water system. 

PURPOSE 

This practice is used to accomplish one or more of the following purposes: 

• Convey water from a supply source to an irrigation system, storage pond, or reservoir 

• Reduce irrigation conveyance water losses by converting from open channel to pipeline 

• Reduce energy use 

CONDITIONS WHERE PRACTICE APPLIES 

This standard applies to water conveyance and distribution pipelines installed above or below ground. 

This standard does not apply to multiple-outlet irrigation system components (e.g., surface gated pipes,

sprinkler lines, or microirrigation tubing). Use NRCS Conservation Practice Standards (CPSs) Irrigation

System, Surface and Subsurface (Code 443), Sprinkler System (Code 442), and Irrigation System,

Microirrigation (Code 441) for these components. 

This practice does not apply to pipelines in systems for animal watering or waste transfer. Use NRCS CPS

Livestock Pipeline (Code 516) to supply animal watering facilities. Use NRCS CPS Waste Transfer (Code

634) to transfer waste material. 

CRITERIA 

General Criteria Applicable to All Purposes 

Ensure that the quantity and quality of the water supply is sufficient for the planned conservation

practice(s) and the system(s) supplied by the pipeline. 

Select pipeline materials suitable for the specific soils, topography, and environmental conditions. 

Design the pipeline to meet all service requirements so that internal pressure at any point, including

hydraulic transients or static pressure, is less than the pressure rating of the pipe. 

Notify landowner and/or contractor of their responsibility to locate all buried utilities in the project area,

including drainage tile and other structural measures. The landowner is also required to obtain all

necessary permits for project installation prior to construction. 
Capacity 

Design sufficient pipeline capacity to convey the design flow rate for the planned conservation practices.

Include reasonable water losses during application or use of the water in the design capacity. 

Friction and other losses 

For design purposes, compute head loss for hydraulic grade line computations using one of the following

equations: Manning’s, Hazen-Williams, or Darcy-Weisbach. Base the equation selection on the given flow

conditions and the pipe materials used. Evaluate and include other head losses (called minor or local

losses) from a change in velocity and direction of flow due to inlet type, valves, bends, enlargements, or

contractions . For pressurized systems, maintain the hydraulic grade line for all pipelines above the top of

the pipeline at all locations for all flows unless specifically designed for negative internal pressures. 

Flexible conduit design 

Design flexible conduits, such as plastic pipe, steel pipe, aluminum pipe, corrugated metal pipe, or ductile

iron pipe, using NRCS National Engineering Handbook (NEH) (Title 210), Part 636, Chapter 52,

“Structural Design of Flexible Conduits,” and the criteria below. 

Plastic pipe (smooth, currugated, or profile wall) 

When operating at design capacity, do not exceed 5-feet-per-second velocity in the full-pipe flow in

pipelines with valves or some other flow control appurtenance placed within the pipeline or at the

downstream end. As a safety factor against surge, keep the working pressure at any point at or below 72

percent of the pressure rating of the pipe. If either of these limits is exceeded, provide measures to

adequately protect the pipeline against transient pressures. 

Smooth wall steel pipe 

Determine the specified maximum allowable pressure using the hoop stress formula, limiting the allowable

tensile stress to 50 percent of the yield-point stress for the material selected. Design stresses for

commonly used steel pipe are shown in 210-NEH-636-52. 

Corrugated metal pipe 

Keep maximum allowable pressure for the pipe at— 

• Twenty feet of head for annular and helical pipe with sealed seams and watertight coupling bands. 

• Thirty feet of head for helical pipe with welded seams, annular ends, and watertight couplings. 

Smooth wall aluminum pipe 

Determine the maximum allowable pressure of the pipe using the hoop stress formula, limiting the allowed

tensile stress to 7,500 pounds per square inch (psi). 

Rigid conduit design 

Design rigid conduits, such as concrete pipe or plastic mortar pipe, using the criteria below. 

Nonreinforced concrete pipe with mortar joints 

Keep the maximum allowable pressure at or below one-fourth of the certified hydrostatic test pressure as

determined by the test procedure described in ASTM C118-15, “Standard Specification for Concrete Pipe

for Irrigation or Drainage.” Also, keep the maximum allowable pressure at or below the amounts indicated

in table 1. 

Table 1: Maximum Allowable Pressure for Nonreinforced Concrete Pipe with Mortar Joints 

Nonreinforced concrete pipe with rubber gasket joints 

Keep the maximum allowable pressure at or below one-third the certified hydrostatic test pressure as

determined by the test procedure described in ASTM C505, “Standard Specification for Nonreinforced

Diameter (inches) Maximum Allowable Pressure (feet)

6 through 8 40

10 and greater 35

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Concrete Irrigation Pipe with Rubber Gasket Joints.” Also, keep the maximum allowable pressure at or

below the amounts indicated in table 2. 

Table 2: Maximum Allowable Pressure for Nonreinforced Concrete Pipe with Rubber Gasket Joints 

Cast-in-place concrete pipe 

Limit the maximum working pressure to 15 feet above the centerline of the pipe. Use cast-in-place

concrete pipe only in stable soils that are capable of being used as the outside form for approximately the

bottom half of the conduit. 

Reinforced concrete pipe with gasket joints 

Limit the maximum allowable pressure at or belowthe rated hydrostatic pressure for the specified pipe

according to appropriate ASTM or American Water Works Association (AWWA) standards. 

Reinforced plastic mortar pipe 

Design the pipeline to meet all service requirements without a static or working pressure at any point

greater than the maximum allowable working pressure of the pipe used. Include freeboard in the static or

working pressure of pipelines open to the atmosphere. Use 50 psi as the minimum acceptable pipe

pressure rating. 

Support of pipe 

Provide support against external and internal forces for both above and below ground pipelines where

needed. Design the pipe support using 210-NEH-636-52. 

Joints and connections 

Design and construct all connections to withstand the pipeline working pressure without leakage and

leave the inside of the pipeline free of any obstructions that would reduce capacity. 

Use the permissible joint deflection from the manufacturer for the joint type and pipe material used. 

For sloping steel pipe, place expansion joints adjacent to and downhill from anchors or thrust blocks. 

For welded pipe joints, install expansion joints, as needed, to limit pipeline stresses to the allowable

values. 

For suspended pipelines, design pipe loading using 210-NEH-636-52. Include the effects of water in the

pipe, wind, ice, thermal expansion and contraction, and the joints and fittings in the suspended pipeline

design. 

Use similar materials, whenever possible, for joints and connections for metal pipes. If dissimilar materials

are used, protect the joints or connections against galvanic corrosion. 

Depth of cover 

Install buried pipe at sufficient depth below the ground surface to provide protection from hazards imposed

by traffic loads, farming operations, freezing temperatures, or soil cracking. 

Ensure pipelines have sufficient strength to withstand all external loads on the pipe for the given

installation conditions. Use appropriate live loads for the anticipated traffic conditions. Refer to 210-NEH636-52, for procedures to analyze external loads on buried pipe. 

Where it is not possible to achieve sufficient cover or sufficient strength, use a carrier (encasement) pipe

or other mechanical measures to protect the pipe. 

Diameter (inches) Maximum Allowable Pressure (feet)

6 through 12 50 

15 through 18 40

21 and greater 30

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Pressure reduction 

Incorporate pressure reduction in circumstances such as head gain exceeding pressure loss by a

significant amount, excessive line pressures for the type of irrigation system, or excessive static

pressures. 

Inlets 

Design inlets with adequate size for the type of entrance condition to ensure design flow capacity without

excessive head losses. 

Provide measures to prevent the inflow of trash or other materials into the pipeline if these materials would

be detrimental to the pipe capacity or performance of the system supplied by the pipeline. 

For gravity flow inlets with square-edged or gated orifices, vent the nappe created by the inflow at the

orifice entrance. 

Water control structures, stands, Z-pipes, and doglegs are all acceptable inlet devices. When using these

inlets, ensure the removal of entrained air. 

Check valves and backflow prevention 

Install a check valve between the pump discharge and the pipeline if detrimental backflow may occur.

Check valves can cause extreme internal pressures due to water hammer if they close too fast as flow

reversal occurs. “Non-slam” type check valves or solenoid-operated valves may be required. 

Use approved backflow prevention devices (such as a chemigation check valve) on all pipelines in which

fertilizer, pesticides, acids, or other chemicals are added to the water supply. 

Valves and other appurtenances 

Ensure the pressure ratings of valves and other appurtenances equals or exceeds the pipeline working

pressure. When lever-operated valves are used, perform an analysis to evaluate the potential for

surge/water hammer assuming an instantaneous valve closure. 

Stands open to the atmosphere 

Stands open to the atmosphere are used when water enters the pipeline to avoid entrapment of air, to

prevent surge pressures and collapse because of vacuum failure, and to prevent pressure from exceeding

the design working stress of the pipe. Design the stand to— 

• Allow a minimum of 1 foot of freeboard. The maximum height of the stand above the centerline of

the mainline pipeline must not exceed the maximum working head of the pipe. 

• Have the top of each stand at least 4 feet above the ground surface except for surface gravity inlets

or where visibility is not an issue. Equip gravity inlets and stands with trash racks and covers. 

• Limit the downward water velocity in the stand to no more than 2 feet per second. Ensure that the

inside diameter of the stand is not less than the inside diameter of the pipeline 

The cross sectional area of a stand open to the atmosphere may be reduced no less than 1 foot above the

top of the upper inlet. If a reduced section is used, design it to allow discharge of the design flow at no

more than 10 feet per second. 

If the water velocity of an inlet pipe exceeds three times the velocity of the outlet, ensure that the

centerline of the inlet has a minimum vertical offset from the centerline of the outlet at least equal to the

sum of the diameters of the inlet and outlet pipes. 

Construct stands of steel pipe or other approved material. Design the stand base to bear the weight of the

stand when full and to prevent movement or undue stress on the pipeline. 

Ensure that sand traps, when combined with a stand, have a minimum inside dimension of 30 inches and

are constructed so the bottom is at least 24 inches below the invert of the outlet pipeline. Ensure that the

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downward velocity of flow of the water in a sand trap does not exceed 0.25 feet per second. Make suitable

provisions for cleaning sand traps. 

Design gate stands so that their dimensions are adequate to accommodate the required gates. Ensure

that gate stands allow adequate access for gate repair. 

Design float stands so that they are large enough to provide accessibility for maintenance. 

Construct stands so that vibration from the pump discharge pipe does not transfer to the stand. 

Pressure-relief (PR) valves are used as an alternative to stands open to the atmosphere. Ensure that all

PR valves serve the PR function of the open stand or vent for which it is an alternative. 

Stands closed to the atmosphere 

If PR valves and air-and-vacuum (AVR) valves are used instead of open stands, all requirements detailed

in the section above, “Stands open to the atmosphere” apply except as modified below. 

Ensure that the inside diameter of the closed stand is equal to or greater than that of the pipeline for at

least 1 foot above the top of the uppermost inlet of outlet pipe. To facilitate attaching the PR valve and the

air-and-vacuum valve, the stand can be capped at this point. If additional height is required, the stand can

be extended to the desired elevation by using the same inside diameter or a reduced cross section. If a

reduced section is used, ensure that the cross-sectional area is such that it would produce an average

velocity of no more than 10 feet per second if the entire flow were discharged through it. If no vertical

offset is required between the pump discharge pipe and the outlet pipeline and the discharge pipe is “doglegged” below ground, extend the stand at least 1 foot above the highest part of the pump discharge pipe. 

Use either of the following two alternative designs for stands requiring no vertical inlet offset (when inlet

velocity is less than three times that of the discharge pipeline): 

• Construct the dogleg section of the pump discharge pipe with the same nominal pipe diameter as

that of the pipeline. 

• Install the PR valve and the air-and-vacuum valve on top of the upper horizontal section of the

dogleg. 

Install PR and air-and-vacuum valves on stands with the nominal size pipe required to fit the valves’

threaded inlets. 

Surge tanks and air chambers 

If surge tanks and/or air chambers are required for control of hydraulic transients or water column

separation, ensure that their size meets the water volume needs of the pipeline without the tank/chamber

being emptied, and that the required flow into the pipeline for the calculated pressure drop is met. 

Pressure-relief valves 

Install a PR valve between the pump discharge and the pipeline if excessive pressure can build up when

all valves are closed. If needed to protect the pipeline against pressure reducing valve malfunction or

failure, install PR valves downstream of pressure-reducing valves. 

Manufacturers of PR valves marketed for use under this standard must provide capacity tables that give

the discharge capacities of the valves at the maximum permissible pressure and differential pressure

settings. These tables must be based on performance tests, and must be the basis for acceptance of

these valves and selection of the design pressure setting. 

Set PR valves to open at a pressure as low as practical, but no greater than 5 psi above the pressure

rating or maximum allowable pressure of the pipe. Ensure that the valves have sufficient flow capacity to

reduce the excessive pressures in the pipeline. 

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Indicate or mark the pressure at which the valves start to open on each PR valve. Seal or otherwise alter

adjustable PR valves to prevent changing the adjustment from that marked on the valve. 

Air-release valves 

Five types of air vents/valves commonly used on irrigation pipelines are continuous-acting air-release

valves (CAV), vacuum-relief valves (VR), air-release and vacuum-relief valves (AVR), combination air

valves (COMB), and open vents. Open vents are described in the section “Vents” below. 

Where the accumulation of air occurs during operation, use a CAV at the appropriate location to release

air from the filled pipeline while under pressure. Normal orifice venting diameter is 1/16 to 3/8 inch. 

Use VR valves for relief of vacuum pressures (i.e., negative pressures) due to sudden gate or valve

closure, pump shutoff, or drainage of the pipeline. 

AVR valves can be used for the same requirements described for VR valves. Use AVR valves to release

air from the pipeline on filling prior to the pipe being pressurized. Use AVR valves to alleviate flow

restrictions, air locks, and water surging due to the presence of air within pipelines. Include air valves at all

high points along the pipeline. Install an air valve at least every 2,500 feet on horizontal runs. 

COMB valves have the combined function of all three valves (CAV, VR, and AVR) in one body. COMB

valves can be used for any of the conditions in which a CAV, VR, or AVR is required. 

If needed to provide positive means for air escape during filling and air entry while emptying, install an

AVR, VR, or COMB valve at all summits, upstream and downstream of all in-line valves as needed, at the

entrance, and at the end(s) of the pipelines. Such valves are needed at these locations if the pipeline is

closed to the atmosphere. However, they are not needed if other features of the pipe system, such as

permanently located sprinkler nozzles or other unclosed service outlets, adequately vent the particular

location during filling and emptying operations. Analyze the use of these system features for airflow rate

and the proper use of such features described in the operation and maintenance (O&M) plan. High points

in the pipeline require a CAV unless an outlet is located at that point. 

In addition to the locations described above, place an AVR or COMB valve at changes of grade in

downward direction of flow in excess of 10 degrees to ensure adequate air release during filling. On long

pipelines (i.e., over 2,500 feet), additional AVR or COMB valves may be required to vent the pipe during

filling. 

For air release, size the AVR or COMB valve to exhaust air from the pipeline at the rate needed to prevent

operational problems with the pipeline, while maintaining the proper operation of the valve. For design

purposes, limit the exhaust pressure differential to 2 psi. 

For vacuum relief, size the AVR, VR, or COMB valves for air entry into the pipeline, ensuring the pipeline

does not collapse due to vacuum created during drainage of the pipeline. For design purposes, limit the

vacuum pressure differential to 5 psi. 

If the required vacuum relief orifice diameter is significantly larger than the required air release orifice

diameter, separate valves may be required to help eliminate excessive water hammer caused when the

air is released too fast from the pipeline. 

Use CAV or COMB valves as needed to permit air to escape while the line is at working pressure. Size

small orifices of these valve types according to the design working pressure and venting requirements

recommended by the valve manufacturer. 

Ensure that the location of the CAV or COMB valves is a sufficient distance downstream from the

introduction of air into the system (under pressure conditions) to allow the air to be collected at the top of

the pipe. Under some circumstances (e.g., pumped system with low pressure or velocity) consideration

should be given to installing vent chambers for CAV or COMB valves. Construct the vent chamber

according to the requirements under the second criteria in the section “Vents” below. 

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In lieu of a detailed design, for the corresponding pipe material below, use the following air valve sizes: 

• For plastic ≤ 50 psi - 0.22 x pipe diameter 

• For plastic > 50 psi - 0.10 x pipe diameter 

• For metal - 0.125 x pipe diameter 

• For concrete - 0.125 x pipe diameter 

Document that the manufacturers of air valves marketed for use under this standard provide dimensional

data or a capacity table based on performance tests, and use these data for the selection and acceptance

of these valves. 

Vents 

Vents that are open to the atmosphere provide for the removal and entry of air and protection from surge.

Use the following design criteria: 

• Ensure that vents have a minimum freeboard of 1 foot above the hydraulic grade line at design

capacity. The maximum height of the vent above the centerline of the pipeline must not exceed the

maximum allowable working pressure of the pipe. 

• Construct a vent chamber to intercept and/or capture air within the pipeline. Ensure that the

chamber intercepts the circumference arc of 75 degrees at the top of the pipe (i.e., a vent chamber

diameter of two-thirds the diameter of the pipeline). Extend the chamber vertically at least one

pipeline diameter up from the centerline of the pipeline. Above this elevation, the vent chamber can

be reduced to a minimum diameter of 2 inches. 

• When an AVR or COMB valve is used instead of a vent, use the above requirements. In addition,

size the reduced section to meet the nominal pipe size required to fit the valve’s threaded inlet. An

acceptable alternative is to install the valve(s) in the side of a service outlet, provided that the

service outlet riser is properly located and adequately sized. If both AVR and PR valves are

required at the location, apply the 10-feet-per-second velocity criterion given under the section

above, “Stands open to the atmosphere,” to the reduced section. 

• Install vent chambers on all open vents and closed vents with air valves when the normal operating

pressure of the pipe is 10 psi or less. 

• Place a vent at the downstream end of laterals, at summits in the line, and at points where the

grade changes more than 10 degrees in a downward direction of flow. 

Outlets 

Appurtenances that deliver water from the pipe system to the field, ditch, reservoir, or surface pipe system

are known as outlets. Ensure that the outlets have adequate capacity to deliver the required flow to— 

• The hydraulic grade line of a pipe or ditch, 

• A point at least 6 inches above the field surface, 

• The design surface elevation in a reservoir, or 

• An individual sprinkler, lateral line, hydrant, or other device at the required operating pressure. 

Design outlets to minimize erosion, physical damage, or deterioration due to exposure. 

Filling 

Ensure that the pipe system has a means of controlling the filling of the pipeline to prevent entrapped air

and excessive transient pressures. 

Filling velocities greater than 1 foot per second in a closed to the atmosphere pipe system (i.e., all outlets

closed) requires special evaluation and provisions to remove entrapped air and prevent transient

pressures. 

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If filling the pipeline at a low flow rate is not possible, design the system for air removal and mitigate

transient pressures at the higher filling rates. 

Flushing 

If the sediment load in the water is significant, design the pipeline to provide adequate velocity to move

sediment through and be flushed out of the pipeline. 

If provisions are needed for flushing sediment or other foreign material, install a suitable valve at the

distant end or low point of the pipeline. 

Draining 

Make provisions for the complete removal of water from the pipeline by gravity or other means when— 

• Freezing temperatures are a hazard. 

• The pipe manufacturer requires draining. 

• Draining the pipeline is recommended. 

Ensure that the water drained from pipelines does not cause water quality, soil erosion, or safety problems

upon release. 

Safe discharge of water 

Make provisions for water discharged from valves, especially air valves and PR valves. Place these

valves so that flows from the valves are directed away from system operators, livestock, electrical

equipment, and other control valves or hook-ups. 

Thrust control 

Abrupt changes in pipeline grade, horizontal alignment, tees, or reduction in pipe size, normally require an

anchor or thrust blocks to absorb pipeline axial thrust. Thrust control is typically needed at the end of the

pipeline and at in-line control valves. 

Follow the pipe manufacturer’s recommendations for thrust control. In absence of manufacturer’s data,

design thrust blocks using 210-NEH-636-52. 

Longitudinal bending 

For plastic pipe, base the allowable longitudinal bending for the pipeline on the material type and the

pressure rating. Ensure that the longitudinal bending is in accordance with industry standards or as

described in 210-NEH-636-52. 

Thermal effects 

For plastic pipe, thermal effects must be properly factored into system design. Pressure ratings for pipes

are normally based on a pipe temperature of 73.4 oF. Reduce the effective pressure rating by an

appropriate amount when the operating temperature is higher than 73.4 oF. 

Ensure that values and procedures for pressure rating reduction follow information described in the 210-

NEH-636-52. 

Physical protection 

Ensure that steel pipe installed above ground is either galvanized or protected with a suitable protective

paint coating, including a primer coat and a minimum of two final coats. 

Ensure that plastic pipe installed above ground is resistant to ultraviolet light throughout the intended life

of the pipe or measures taken to protect the pipe from damage due to ultraviolet light. 

Protect all pipes from hazards presented by traffic loads, farm operations, freezing temperatures, fire,

thermal expansion and contraction. Take reasonable measures to protect the pipe from potential

vandalism. 

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Corrosion protection 

Ensure that all metal to metal fittings, such as risers, bends, tees, and reducers, are of similar metals. If

dissimilar metals are used, protect the fittings against galvanic corrosion (e.g., separate dissimilar metals

with rubber or plastic insulator). 

Galvanize bolts used to join galvanized steel, plastic coated, stainless steel, or otherwise protected to

prevent galvanic corrosion. Bolts used to join aluminum, other than aluminum alloy bolts, must be plastic

coated or otherwise protected to prevent galvanic corrosion. 

Provide interior protective coatings when the pH of the water falls outside the ranges shown in table 3. 

Table 3: Ranges in Water pH Values Used to Determine the Need for Interior Protective Coatings 

Unlined steel pipelines can experience corrosion from very pure water (e.g., snowmelt). Provide corrosion

protection if the Langelier Saturation Index is less than -1. 

Galvanized steel pipe can be used when the soil resistivity is greater than 4000 ohms-centimeter (ohmcm). 

Use hot­dipped asphalt or polymeric-coated galvanized steel pipe if the soil resistivity along any part of the

pipeline is between 3000 and 4000 ohm­cm. In addition to the above coatings, provide cathodic protection

for galvanized steel pipe if the soil resistivity is less than 3000 ohm-cm. 

Aluminized steel pipe can be used when the soil resistivity is greater than 1500 ohm-cm and the soil pH is

between five and nine. 

Aluminum alloy pipe can be used when the soil resistivity is greater than 500 ohm-cm and the soil pH is

between four and ten. 

When cathodic protection is required, electrically bridge joints and connecting bands to ensure continuous

flow of current. Place a dielectric connection between the pump and the pipeline and between pipes with

different coatings. 

Design the total current required, kind and number of anodes needed, and life expectancy for the cathodic

protection in accordance with NRCS Technical Note (Title 210), Design Engineering, Design Note 12,

“Control of Underground Corrosion” or equivalent method. 

Resistivity measurement requirements for metal pipe 

If risk of corrosion is “high” based on the Cooperative Soil Survey’s Soil Features Report, conduct soilresistivity measurements to determine corrosion protection requirements. For this purpose, make field

resistivity measurements or take samples for laboratory analysis at least every 400 feet along the

proposed pipeline route and at points where a visible change in soil characteristics occurs. If adjacent

readings differ markedly, take additional measurements to locate the point of change. Make resistivity

determinations at two or more depths in the soil profile at each sampling station, with the lowest depth at

the stratum in which the pipe will be laid. Use the lowest value of soil resistivity found at each sampling

station as the design value for that station. 

After excavation of the pipe trench, make a detailed soil resistivity survey as a verification of the final

required cathodic protection. At this time, make resistivity measurements in each exposed soil horizon at

intervals not exceeding 200 feet. Use the lowest value of soil resistivity found at each sampling station as

the design value for that station. If design values for adjacent stations differ significantly, make additional

intermediate measurements. 

Material Water pH

Aluminized steel Less than 5 or greater than 9

Galvanized steel Less than 6 or greater than 10

Aluminum alloy Less than 4 or greater than 10

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Electric fields 

An electric field can develop where a metal pipeline is installed adjacent to an existing metal pipeline. This

situation can adversely affect the new pipeline. Protect the new pipeline from this condition. 

Environmental constraints for aluminum 

Evaluate water quality for aluminum pipeline installations. A copper content in excess of 0.02 parts per

million produces nodular pitting and rapid deterioration of the pipe if water is allowed to become stagnant.

When the copper content exceeds this limit, design the pipeline to allow draining after each use, or avoid

the use of aluminum pipe. 

Provide protection from corrosion for aluminum pipe installed in contact with concrete. 

Environmental constraints for concrete 

Do not install concrete pipelines on sites where the sulfate concentration in the soil or soil water exceeds

1.0 percent. On sites where the sulfate concentration is more than 0.1 percent but not more than 1.0

percent, concrete pipe can be used only if the pipe is made with Type V or Type II cement, with tricalcium

aluminate content not exceeding 5.5 percent. 

Additional Criteria for Reducing Energy Use 

Provide analysis to demonstrate reduction of energy use from practice implementation. 

Calculate the reduction of energy use by comparing the planned average annual or seasonal energy use

to previous operating conditions. 

CONSIDERATIONS 

Additional Considerations for Safety 

Pipelines may present a threat to the safety of people during both installation and operation. Consider

safety as follows: 

• Address trench safety in design and during construction. 

• Provide protection for people from inlets of pipelines and open stands. 

• Provide protection for people from water blowing from PR, air-release, and other valves. 

• Determine the existence or nonexistence of underground utilities prior to construction. 

• Install a locate wire or safety tape above a buried pipe for future reference. Survey with GPS to

mark grade and alignment changes. 

Additional Considerations for Economics 

Economics can be a major factor in pipeline design, as follows: 

• Select pipe based on lifetime energy requirements, as well as initial costs of materials. 

• Select pipe material based upon expected life of practice. 

• Consider hydropower applications as alternatives to use of pressure reduction valves or reduced

pipe diameter to induce friction loss. 

Additional Considerations for Water Quality and Quantity 

Consider the effects of an irrigation pipeline on water quality and quantity when designing an irrigation

pipeline. Consider the effects— 

• On the water budget, especially on infiltration and evaporation. 

• On downstream flows or aquifers that would affect other water uses or users. 

• On potential use for irrigation management. 

• Of installing a pipeline on vegetation that may have been located next to the original conveyance. 

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• Of installing the pipeline (replacing other types of conveyance) on channel erosion or the movement

of sediment and soluble and sediment-attached substances carried by water. 

• On the movement of dissolved substances into the soil and on percolation below the root zone or to

ground water recharge. 

• Of controlled water delivery on the temperatures of water resources that could cause undesirable

effects on aquatic and wildlife communities. 

• On wetlands or water-related wildlife habitats. 

• On the visual quality of water resources. 

Additional Considerations for the Environment 

Base pipe material selection on exposure considerations (such as soil resistivity, pH, sunlight, and traffic).

Soil texture, resistivity, pH, moisture content, redox potential, and depth are important soil properties to be

aware of for pipelines and in reducing soil limitations related to corrosivity or packing of soil material. Refer

to soil survey information of the area, and onsite soil investigations should be considered during planning. 

The Langelier Saturation Index and related indices may be a factor in determining type of material to use

for a pipeline. 

Pipelines installed below the ground surface should have a soil plan describing soil reconstruction of

disturbed soil during and after pipeline installation so original soil productivity is restored after pipeline

installation. Appropriate vegetation should be established to stabilize disturbed areas that will not be

cropped. 

PLANS AND SPECIFICATIONS 

Prepare plans and specifications for irrigation pipelines that describe the requirements for applying the

practice according to this standard. Include, at a minimum, in the plans and specifications— 

• A plan view of the layout of the pipeline. 

• Profile of the irrigation pipeline if not parallel to the ground surface with a uniform minimum depth of

cover. 

• Pipe material and sizes. 

• Pipe joint requirements. 

• Site-specific construction specifications that describe in writing the installation of the irrigation

pipeline. Include the specification for leak testing of the irrigation pipeline. 

• Depth of bedding, embedment, and backfill requirements. 

• Thrust block design. 

• Location and sizing of— 

• PR valves. 

• Continuous-acting air-release valves. 

• Vacuum-relief valves. 

• Air-release/vacuum-relief valves. 

• Combination air valves. 

• Open vents. 

• Disposal requirements for excess soil material. 

• Vegetative establishment requirements. 

• Location of utilities and notification requirements. 

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OPERATION AND MAINTENANCE 

Develop an O&M plan for each pipeline system installed. Ensure that the plan describes the required

actions so that the pipeline system performs adequately throughout its expected life. 

Include procedures for— 

• Draining the pipeline. 

• Marking crossing locations. 

• Valve operation to prevent pipe or appurtenant damage. 

• Appurtenance or pipe maintenance. 

• Recommended operating procedures, as needed within the O&M plan. 

Include the procedure to monitor any cathodic protection systems. 

Describe the filling procedure, which details allowable flow rates and appurtenance operation at the

various phases of the filling process, to ensure safe filling of the pipeline. Use flow measuring

appurtenances such as flow meters or weirs, or other means (e.g., number of turns of a gate valve) to

determine the rate of flow into the pipeline system. Provide this information to the operator, and

incorporate it in the O&M plan as appropriate. 

REFERENCES 

ASTM C118-15. 2015. Standard Specification for Irrigation Pipe for Irrigation or Drainage. ASTM

International. West Conshohocken, PA. 

ASTM C505-15. 2015. Standard Specification for Nonreinforced Concrete Irrigation Pipe with Rubber

Gasket Joints. ASTM International. West Conshohocken, PA. 

ASTM F1668-16. 2016. Standard Guide for Construction Procedures for Buried Plastic Pipe. ASTM

International. West Conshohocken, PA. 

USDA NRCS. 2005. National Engineering Handbook (Title 210), Part 636, Chapter 52, Structural Design

of Flexible Conduits. Washington, D.C. https://directives.sc.egov.usda.gov/

USDA NRCS. 2017. National Engineering Handbook (Title 210), Part 645, Chapter 15, Pipe. Washington,

D.C. https://directives.sc.egov.usda.gov/

USDA NRCS. 1971. Technical Note (Title 210), Design Engineering, Design Note 12, Control of

Underground Corrosion. Washington, D.C. https://directives.sc.egov.usda.gov/

-CPS-12

NRCS, NHCP

430

September 2020R