NATURAL RESOURCES CONSERVATION SERVICE CONSERVATION PRACTICE STANDARD ANIONIC POLYACRYLAMIDE (PAM) EROSION CONTROL
EROSION CONTROL: DEFINITION
Erosion control through application of watersoluble anionic polyacrylamide (PAM).
EROSION CONTROL: PURPOSE
This practice is applied as part of a conservation management system to support one or more of the following:
· Minimize or control irrigation-induced soil erosion.
· Reduce wind and/or precipitation erosion.
EROSION CONTROL: CONDITIONS WHERE PRACTICE APPLIES
· On irrigated lands susceptible to irrigationinduced erosion, excluding peat soils, and where the sodium adsorption ratio (SAR) of irrigation water is less than 15;
· On areas where the timely establishment of vegetation may not be feasible or where vegetative cover is absent or inadequate;
· On areas where plant residues are inadequate to protect the soil surface from wind erosion; and
· On sites where disturbance activities prevent establishment or maintenance of a cover crop;
This standard does not apply to the application of polyacrylamides to flowing, non-irrigation, waters.
EROSION CONTROL: CRITERIA
General Criteria Applicable To All Purposes Changes in management shall be implemented where increases in soil infiltration rates are a result of implementing this practice.
The polyacrylamide (PAM) shall:
· be of the anionic type meeting acrylamide monomer limits of £ 0.05 percent (%),
· have a charge density of 10 to 55%, by weight
· have a molecular weight of 6 to 24 Mg/mole.
· be mixed and/or applied in accordance with all Occupational Safety and Health Administration (OSHA) Material Safety Data Sheet requirements and the manufacturer’s recommendations for the specified use.
· conform to all federal, state, and local laws, rules, and regulations.
EROSION CONTROL: Additional Criteria Applicable To Irrigation Induced Soil Erosion Surface Irrigation
PAM shall be used during the first irrigation and after any soil disturbance (pre-irrigation is considered irrigation) and during later irrigations if soil movement is observed.
Mixed concentrations of PAM shall be added to irrigation water only during the advance phase of a surface irrigation. The advance phase shall be considered the time irrigation starts until water has advanced to the end of the field. Dry or “patch” treatments of PAM shall be placed over an area of the first five (5) feet of furrow.
The resulting concentration of PAM in irrigation water shall not exceed 10 ppm of pure form polyacrylamide, applied on a total product basis.
EROSION CONTROL: Sprinkler Irrigation
The maximum application rate of Polyacrylamide active ingredient shall not exceed four (4) pounds per acre (lb/ac) per single application event.
PAM mixtures will be totally mixed and liquefied prior to injection into the irrigation system.
Injection shall occur on the downstream side of all screens and/or filters and conform to all federal and state chemigation standards.
EROSION CONTROL: Additional Criteria Applicable To Reduce Wind and/or Precipitation Erosion
The maximum application rate of pure form polyacrylamide shall not exceed 200 lb/ac per year. Emulsion batches shall be mixed with pure form polyacrylamide not exceeding 200 pounds per batch.
Application method shall insure uniform coverage to the target area, minimizing drift to non-target areas.
EROSION CONTROL: CONSIDERATIONS
The following relate to the application of the polyacrylamide practice that may enhance, or avoid problems with the practice but are not required to insure its basic conservation function.
EROSION CONTROL: General
PAM application rates may need to be adjusted based on soil properties, slope, and type of erosion targeted.
Where reasonably possible, tailwater or runoff containing PAM should be stored for re-use or recycled on other land areas.
Use of polyacrylamide in combination with other conservation and Best Management Practices will improve erosion control.
EROSION CONTROL: Irrigation Induced Erosion Considerations
Other conservation treatments such as land leveling, irrigation water management, reduced tillage, reservoir tillage, crop rotations, etc. should be used in conjunction with this practice to control irrigation-induced erosion.
PAM may result in an increase in surface irrigation infiltration of up to 60%, with 15% being typical on medium textured soils.
To compensate for PAM changes in infiltration, adjustments in flow rates, time of set, and tillage practices should be considered.
Adjustment from maximum PAM rates and volumes should be considered so long as no visible erosion occurs.
Secondary applications on undisturbed soil may be needed in surface irrigation when sediment or erosion is noted.
Sprinkler systems will likely need multiple applications to achieve a significant erosion reduction.
For sprinkler systems, before and after injecting concentrated liquid PAM (30 to 50% active ingredient) into sprinkler irrigation systems, it is a good practice to pump a surfactant (crop oil) through the injection system (pump, tubing, valves, etc.). Surfactants provide a buffer between
PAM and water so non-flowing PAM does not contact water and form a gelatinous mass that can plug valves and tubing.
For sprinkler injection, the injection pump should be started after water is flowing in the sprinkler system and stopped when the irrigation pump stops.
Applications at the end of the season are discouraged, unless the field has been recently tilled.
EROSION CONTROL: Wind or Precipitation Erosion Considerations
Adding seed to polyacrylamide mixture may provide additional erosion protection beyond the life of the PAM material.
PAM may improve water quality, infiltration, soil fertility, and air quality.
EROSION CONTROL: Safety and Health
Use proper personal protective equipment, e.g. gloves, masks, and other health and safety precautions in accordance with the label, industry, and other federal or state rules and guidelines.
If inhaled in large quantities, PAM dust can cause choking and difficulty in breathing. Persons handling and mixing PAM shall use a dust mask of a type recommended by the manufacturer. PAM solutions can cause surfaces, tools, etc. to become very slippery when wet. Clean liquid PAM spills with dry absorbent material (sawdust, soil, cat litter, etc.) and sweep/collect dry PAM material without washing with water.
EROSION CONTROL: PLANS AND SPECIFICATIONS
Specifications will be developed site specifically for each application. Specifications for this practice will be prepared for each field or treatment unit according to the criteria, considerations, and operation and maintenance described in this standard. Specifications shall be recorded using approved specification sheets, job sheets, narrative statements in the conservation plan, or other acceptable documentation.
EROSION CONTROL: OPERATION AND MAINTENANCE
An Operation and Maintenance Plan must be prepared for use by the landowner or operator responsible for PAM application. The plan should provide specific instructions for PAM applications to insure it is used properly. Plan items may consist of:
· Reapply PAM to disturbed or tilled areas, including high traffic use areas.
· Monitoring advance phases of the irrigation to assure applications are discontinued when runoff begins.
· Equipment is operated and maintained to provide uniform application rates.
· Maintenance of screens and filtering facilities.
· Rinse all PAM mixing and application equipment thoroughly with water to avoid formation of PAM residues.
· PAM is a flocculating agent that may cause deposition in downstream watercourses or other locations when it comes in contact with sediment-laden waters. Downstream deposition from the use of PAM may require periodic cleaning to maintain normal functions.