Code of Maine Rules › 01 - DEPARTMENT OF AGRICULTURE, CONSERVATION AND FORESTRY › 001 - AGRICULTURE - GENERAL › Chapter 565 - Nutrient Management Rules › ATTACHMENTS › Attachment B - Construction and Maintenance of Filter Strips and Vegetated Treatment Area

Current through 2024-29, July 17, 2024
NRCS Codes 393 and 635
Filter Strips and Vegetated Treatment Areas Natural
					 Resources Conservation Service
CONSERVATION PRACTICE STANDARD
FILTER STRIP
Code 393
(Ac)
DEFINITION
A strip or area of herbaceous vegetation that removes
					 contaminants from overland flow.
PURPOSE
Reduce suspended solids and associated contaminants
						in runoff and excessive sediment in surface waters.
										Reduce dissolved contaminant loadings in
						runoff.
										Reduce suspended solids and associated contaminants
						in irrigation tailwater and excessive sediment in surface waters.
CONDITIONS WHERE PRACTICE APPLIES
Filter strips are established where environmentally
					 sensitive areas need to be protected from sediment, other suspended solids, and
					 dissolved contaminants in runoff.
CRITERIA
General Criteria Applicable to All
					 Purposes
Overland flow entering the filter strip will be uniform
					 sheet flow.
Concentrated flow will be dispersed before it enters the
					 filter strip.
The maximum gradient along the leading edge of filter strip
					 will not exceed one-half of the up-and-down-hill slope percent, immediately
					 upslope from the filter strip, up to a maximum of five percent.
Filter strips will not be used as a travel lane for
					 equipment or livestock.
Additional Criteria to Reduce Dissolved
					 Contaminants, Suspended Solids and Associated Contaminants in Runoff and
					 Excessive Sediment in Surface Waters.
The filter strip will be designed to have a 10-year life
					 span, following the procedure in Agronomy Technical Note No. 2, "Using Revised
					 Universal Soil Loss Equation, Version 2 (RUSLE2) for the Design and Predicted
					 Effectiveness of Vegetative Filter Strips (FVS) for Sediment," based on the
					 amount of sediment delivery to the upper edge of the filter strip and ratio of
					 filter strip flow length to length of flow path from the contributing area. The
					 minimum flow length through the filter strip will be 20 feet for suspended
					 solids and associated contaminants in runoff and 30 feet for dissolved
					 contaminants and pathogens in runoff.
http://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=18578.wba
The filter strip will be located immediately downslope from
					 the source area of contaminants.
The drainage area immediately above the filter strip will
					 have a slope of one percent or greater.
Vegetation.
The filter strip will be
					 established to permanent herbaceous vegetation.
Species selected will be-
Able to withstand partial burial from sediment
						deposition.
										Tolerant of herbicides used on the area that
						contributes runoff to the filter strip.
										Stiff stemmed and a high stem density near the ground
						surface.
										Suited to current site conditions and intended
						uses.
										Able to achieve adequate density and vigor within an
						appropriate period to stabilize the site sufficiently to permit suited uses
						with ordinary management activities.
Plant species, rates of seeding (lbs/ac), vegetative
					 planting (plants/ac), minimum quality of planting stock (pure live seed [PLS]
					 or stem caliper), and method of establishment shall be specified before
					 application. Only viable, high quality seed or planting stock will be
					 used.
BPerform site preparation and seeding/planting at a time
					 and in a manner that best ensures survival and growth of selected species.
					 Successful establishment parameters, (e.g., minimum percent ground/ canopy
					 cover, percent survival, stand density) will be specified before
					 application.
Schedule planting dates during periods when soil moisture
					 is adequate for germination and establishment. Seeding will be timed so that
					 tillage for adjacent crop does not damage the seeded filter strip.
Where the purpose is to remove phosphorus, remove (or
					 harvest) the filter strip above ground biomass at least once each year.
The minimum seeding and stem density will be equivalent to
					 the seeding rate for a high quality grass hay seeding rate for the climate area
					 or the density of vegetation selected in current water erosion technology to
					 determine trapping efficiency, whichever is the higher seeding rate.
Additional Criteria
to Reduce Suspended
					 Solids and Associated Contaminants in Irrigation Tailwater and Excessive
					 Sediment in Surface Waters.
Filter strip vegetation will be a small grain or other
					 suitable annual plant.
The seeding rate shall be sufficient to ensure that the
					 plant spacing does not exceed 4 inches (about 16-18 plants per square
					 foot).
Establish filter strips prior to the irrigation season so
					 that the vegetation is mature enough to filter sediment from the first
					 irrigation. A minimum flow length of 20 feet is recommended.
CONSIDERATIONS
General
					 Considerations.
Filter strip width (flow length) can be increased as
					 necessary to accommodate harvest and maintenance equipment.
Filters strips with the leading edge on the contour will
					 function better than those with a gradient along the leading edge.
Seeding rates that establish a higher stem density than the
					 normal density for a high quality grass hay crop will be more effective in
					 trapping and treating contaminants.
When needed, invasive plant species may be controlled
					 through mowing, herbicides, and hand weeding.
Consideration for Reducing Suspended Solids and
					 Associated Contaminants in Runoff.
Increasing the width of the filter strip beyond the minimum
					 required will increase the potential for capturing more contaminants in
					 runoff.
Considerations for Creating, Restoring or Enhancing
					 Herbaceous Habitat for Wildlife and Beneficial Insects and Pollinators
.
					 Filter strips are often the only break in the monotony of intensively-cropped
					 areas. The wildlife and pollinator benefits of this herbaceous cover can be
					 enhanced by the following:
When appropriate, use native grass species that
						fulfill the purpose(s) of the practice while also providing habitat for
						priority wildlife.
										Adding herbaceous plant species (including native
						forbs) to the seeding mix that are beneficial to wildlife and pollinators and
						are compatible for one of the listed purposes. Changing the seeding mix should
						not detract from the purpose for which the filter strip is
						established.
										Increasing the width beyond the minimum required. The
						additional area can increase food and cover for wildlife and
						pollinators.
										Management activities on filter strips (mowing,
						burning, or light disking), should not be done more often than every other year
						with frequency dependent on geographical location to maintain the purpose(s) of
						the practice.
										Management activities should be completed outside of
						the primary nesting, fawning, and calving seasons. Activities should be timed
						to allow for regrowth before the growing season ends.
										Organic producers should submit plans and
						specifications to their certifying agent for approval prior to installation, as
						part of the organic producer's organic system plan.
Considerations to Maintain or Enhance Watershed
					 Functions and Values.
Filter strips may be used to enhance connectivity
					 of corridors and noncultivated patches of vegetation within the watershed,
					 enhance the aesthetics of a watershed, and be strategically located to reduce
					 runoff, and increase infiltration and groundwater recharge throughout the
					 watershed.
Increase Carbon Storage.
Increasing the width
					 of the filter strip beyond the minimum required will increase potential for
					 carbon sequestration.
PLANS AND SPECIFICATIONS
Specifications for establishment and operation of this
					 practice will be prepared for each field or treatment unit. Record the
					 specifications using the implementation requirements document. The
					 specifications will identify at a minimum the following:
Practice purpose(s).
										Length, width (width refers to flow length through
						the filter strip), and slope of the filter strip to accomplish the planned
						purpose(s).
										Plant species selection and
						seeding/planting/sprigging rates to accomplish the planned purpose.
										Planting dates and planting method(s).
										Specific care and handling requirements of the seed
						or plant material to ensure that planted materials have an acceptable rate of
						survival.
										A statement that only viable, high quality, and
						adapted seed will be used.
										Site preparation instructions sufficient to establish
						and grow selected species.
OPERATION AND MAINTENANCE
For the purposes of filtering contaminants and nutrients
					 (phosphorus), permanent filter strip vegetative plantings will be harvested and
					 removed as appropriate to encourage dense growth, maintain an upright growth
					 habit and remove nutrients and other contaminants that are contained in the
					 plant tissue.
Control undesired weed species, especially State-listed
					 noxious weeds.
Inspect the filter strip after storm events and repair any
					 gullies that have formed, remove unevenly deposited sediment accumulation that
					 will disrupt sheet flow, reseed disturbed areas and take other measures to
					 prevent concentrated flow through the filter strip.
Apply supplemental nutrients as needed to maintain the
					 desired species composition and stand density.
Periodically regrade and reestablish the filter strip area
					 when sediment deposition at the filter strip-field interface jeopardizes its
					 function. Reestablish the filter strip vegetation in regraded areas, if
					 needed.
If grazing is used to harvest vegetation from the filter
					 strip, the grazing plan must ensure that the integrity and function of the
					 filter strip is not adversely affected.
REFERENCES
Dillaha, T.A., J.H. Sherrard, and D. Lee. 1986. Long-Term
					 Effectiveness and Maintenance of Vegetative Filter Strips. VPI-VWRRC Bulletin
					 153.
Dillaha, T.A., and J.C. Hayes. 1991. A Procedure for the
					 Design of Vegetative Filter Strips: Final Report Prepared for U.S. Soil
					 Conservation Service.
Foster, G.R. Revised Universal Soil Loss Equation, Version
					 2 (RUSLE2) Science Documentation (In Draft). USDA-ARS, Washington, DC.
					 2005.
Renard, K.G., G.R. Foster, G.A. Weesies, D.K. McCool, and
					 D.C. Yoder, coordinators. 1997. Predicting Soil Erosion by Water: A Guide to
					 Conservation Planning with the Revised Universal Soil Loss Equation (RUSLE).
					 U.S. Department of Agriculture. Agriculture Handbook 703.
Revised Universal Soil Loss Equation Version 2 (RUSLE2) Web
					 site (checked May 2007):
http://fargo.nserl.purdue.edu/rusle2_dataweb/RUSLE2_Index.htm.
M.G. Dosskey, M.J. Helmers, and D.E. Eisenhauer 2008. A
Design Aid for Determining Width of Filter
Strips. Journal
of Soil and Water Conservation.
July/Aug
2008
-vol.
					 63, no. 4.
NATURAL RESOURCES CONSERVATION SERVICE CONSERVATION
					 PRACTICE STANDARD
VEGETATED TREATMENT AREA
CODE 635
(Ac.)
DEFINITION
An area of permanent vegetation used for agricultural
					 wastewater treatment.
PURPOSE
Improve water quality by using vegetation to reduce the
					 loading of nutrients, organics, pathogens, and other contaminants associated
					 with livestock, poultry, and other agricultural operations.
CONDITIONS WHERE PRACTICE APPLIES
This practice applies where:
A vegetated treatment area (VTA) can be constructed,
						operated and maintained to treat contaminated runoff from such areas as
						feedlots, feed storage, compost areas, solid manure storage areas, barnyards,
						and other livestock holding areas; or to treat process wastewater from
						agricultural operations.
										A VTA is a component of a planned agricultural waste
						management system.
CRITERIA
Size the total treatment area for the VTA on both the
					 contributing site water runoff and vegetation nutrient balances.
Water balance is the soil's capacity to infiltrate
						and retain runoff within the root zone. Base the runoff determination on the
						most restrictive soil layer within the root zone regardless of its thickness.
						Use the soil's water holding capacity in the root zone, infiltration rate,
						permeability, and hydraulic conductivity to determine its ability to absorb and
						retain runoff.
										Nutrient balance utilizes the nutrients from the
						waste runoff to meet the nutrient removal requirements in the harvested
						vegetation. Base the nutrient balance on the most limiting nutrient (i.e.
						nitrogen or phosphorus).
Divert uncontaminated water from the treatment area to the
					 fullest extent possible unless additional moisture is needed to manage
					 vegetation growth in the treatment area.
Establish permanent vegetation in the treatment area. Use a
					 single species or a mixture of grasses, legumes, and other forbs adapted to the
					 soil and climate. Select species to meet the current site conditions and
					 intended use. Selected species will have the capacity to achieve adequate
					 density, vigor, and yield within an appropriate time frame to treat
					 contaminated runoff. Complete site preparation and seeding at a time and in a
					 manner that best ensures survival and growth of the selected species.
Select vegetation that will withstand anticipated wetting
					 or submerged conditions. Harvest vegetation as appropriate to encourage dense
					 growth, maintain an upright growth habit, and remove nutrients and other
					 contaminants that are contained in the plant tissue.
Design the VTA based on the need to treat the runoff volume
					 from the 25-year, 24-hour storm event from the agricultural animal management
					 facility. Infiltrate a portion or the entire volume of the design storm, based
					 on management objectives. Unless discharge is permitted by applicable
					 regulations, store the non-infiltrated portion of the design volume for
					 utilization or treatment.
Exclude all livestock, including grazing, from the
					 VTA.
Apply discharge into and through vegetated treatment area
					 as sheet flow. To encourage sheet flow across the treatment area, provide a
					 means to disperse concentrated flow, such as a ditch, curb, gated pipe, level
					 spreader, or a sprinkler system. Complete land grading and install structural
					 components necessary to maintain sheet flow throughout the treatment
					 area.
Limit the natural or constructed slope of the VTA from 0.3
					 to 6 percent. The minimum entrance slope to the VTA is 1 percent.
Use NRCS Conservation Practice Standard (CPS) Code 632,
					 Waste Separation Facility, to pretreat influent with waste separation (i.e.,
					 settling basin) to reduce organic loading and nutrients to levels that are
					 tolerated by the VTA and to prevent excessive accumulation of solids in the
					 treatment area.
Utilize inlet control structures to control the rate and
					 timing of inflow during normal operations and to control inflow as necessary
					 for operation and maintenance.
Locate VTA outside of floodplains. However, if site
					 restrictions require location within a floodplain, provide protection from
					 inundation or damage from a 25-year flood event, or larger, if required by
					 regulation.
Install VTA where the water table is either naturally deep
					 or artificially lowered so that the infiltrated runoff does not mingle with the
					 groundwater at the bottom of the root zone. Subsurface drainage within the VTA
					 is not allowed. Subsurface drainage may be used to lower the seasonal high
					 water table to an acceptable level provided the subsurface drain lines are at
					 least 10 feet away from the VTA boundary.
Unless soil moisture can be maintained to prevent drying
					 and cracking, do not plan infiltration areas where soil features such as
					 cracking will result in preferential flow paths that transport untreated runoff
					 from the surface to below the root zone.
Ensure that appropriate erosion control measures and sheet
					 flow control measures (i.e., gravel or rock spreaders) are adequately addressed
					 over the entire length of the VTA.
MAINE DESIGN CRITERIA
For the purposes of this standard, the following
					 definitions apply:
-Intermittent or Perennial Stream: Any stream with a
					 watershed greater than 100 acres.
-Sensitive Habitat: Rare or Exemplary natural communities
					 or ecosystems as designated by the Maine Natural Areas Program or the U.S. Fish
					 and Wildlife Service (USFWS), a pond or a fully functioning forested wetland as
					 determined by the State Soil Scientist (SSS) or representative.
A VTA shall not be located within 300 feet of an
					 intermittent or perennial stream or other sensitive habitat when used for any
					 of the following:
Treats runoff from a structure that services more
						than 15 animal units
										Treats runoff from a composting facility that
						contains carcasses, offal, or meat scraps This includes, but is not limited to
						runoff from heavy use areas, waste storage facilities, compost facilities or
						silos.
If there are no other feasible means to address an existing
					 water quality resource concern, exceptions can be made to the above criteria by
					 the State Conservation Engineer (SCE).
All VTA's, regardless of number of AU served, shall
					 use the following criteria based on water balance to size the
					 VTA:
No VTA shall be wider than 60 feet. No flow length
					 shall be greater than 100 feet. Therefore, no VTA shall be greater than 6,000
					 square feet.
To encourage sheet flow, provide retention of peak runoff,
					 and allow for settling of incidental particulates, each VTA shall have a
					 retention area prior to Level Lip Spreader. The retention area has to meet the
					 same separation distances as the treatment strip. Use Table 1 to size the
					 retention area.
Retention areas shall not be more than 60 feet long and
					 should not be less than 6 feet wide. Maximum retention area width can be up to
					 10 feet wide to accommodate maintenance equipment needed to clean out the
					 retention area. Use NRCS Conservation Practice Standard (CPS) Code 632, Waste
					 Separation Facility, as needed, to pretreat influent with waste separation
					 (i.e. settling basin) to reduce organic loading and nutrients to levels that
					 are tolerated by the VTA and to prevent excessive accumulation of solids in the
					 retention area. NRCS CPS Code 629, Waste Treatment shall also be followed when
					 treating silage leachate.
Table 1: Volume of Retention Area
Impervious surface use
Area of impervious surface used to calculate
								VTA size (y) Units = sq. ft.
Volume of retention area prior to sheet flow
								release (V) Units = cu. ft.
Animal feedlot
Area where animals have access
V = 0.125y
Silage storage
Area where silage is stored
V = 0.125y
Cull potato storage
Area where potatoes are stored
V = 0.125y
Manure storage
Area where manure is stacked
V = 0.125y
Compost amendment storage
Area where amendments are stacked
V = 0.125y
Composting
Area for composting
V = 0.06y
TREATMENT STRIP SITING
					 CRITERIA
Consult with a Resource Soil Scientist to locate proposed
					 VTA's and determine if any modifications are needed to meet separation
					 distances and soils criteria.
*
SOIL PERMEABILITY:
The design shall be based on the most restrictive soil
					 layer within the root zone. The
Maximum Permeability
in the root
					 zone shall be less than or equal to
2.0 in/hr
,
UNLESS:
1. A natural or constructed barrier within the soil profile
					 mitigates the potential of ground water contamination. In Maine, a natural
					 barrier would be a dense substratum such as a glacial till hardpan or heavy
					 marine or lacustrine sediment that results in a seasonally perched water table.
OR
2. Greater than or equal to
18 inches
of loamy
					 fine sand or finer soil material (permeability < 2.0 in/hr) exists over soil
					 material with permeability > 2.0 in/hr such as sand or gravel.
OTHER VTA SITE/SOIL CHARACTERISTIC
					 REQUIREMENTS:
Minimum Depth to Bedrock: 18 inches
										Minimum Depth to Seasonal High Water Table: 15
						inches
										Slope Range: 1 - 6 percent
SETBACKS FROM RESOURCE CONCERNS:
Wells: 100 feet
										Receiving Surface Water: 100 ft. < 15 animal
						units, 300 ft. > 15 animal units OR carcass/offal/meat composting
										Public Water Supply: 300 feet
										Other options or modifications, such as ROOFED AREAS,
						will be necessary if the above unsuitable conditions exist in potential
						treatment areas. See NRCS CPS 367, Roofs and Covers for details.
Use Table 2 to size the vegetated treatment area based on
					 soil type.
Table 2: Vegetated Treatment Area Size Based on Soil
					 Type
SOIL / PARENT MATERIAL TYPES
SOIL PERMEABILITY RANGE
SIZE RATIO OF IMPERMEABLE SURFACE (y) TO VEGETATED
								TREATMENT AREA
1. COARSE LOAMY & SANDY GLACIAL TILLS
2. COARSE SILTY SEDIMENTS
3. COARSE SILTY ALLUVIAL DEPOSITS
0.6 - 2.0 in/hr
1 : 1
FINE LOAMY AND SILTY GLACIAL TILLS
0.2 - 0.6 in/hr
1 : 1.5
FINE SILTY SEDIMENTS
0.06 - 0.2 in/hr
1 : 1.8
ADDITIONAL CRITERIA FOR DOSING SYSTEMS
Distribute the effluent over the VTA through sprinkler
					 irrigation or other pressure dosing system. Match the application rate of
					 sprinkler nozzles to the most restrictive soil infiltration rate or other
					 factors to prevent effluent from discharging from the VTA.
CONSIDERATIONS
Direct contaminated effluent to a waste storage facility
					 during excessively wet or cold climatic conditions.
Additional nutrient and infiltration design guidance in
					 Vegetated Treatment Systems for Open Lot Runoff, (Koelsch, et. al.,
					 2006).
Provide more than one VTA to allow for resting, harvesting
					 vegetation, and maintenance, and to minimize the potential for
					 overloading.
If impervious area requires more than 6,000 square feet of
					 vegetated filter area for treatment, then consider installing multiple filter
					 areas and divide impervious area flow accordingly.
Provide additional storage in the basin collection area to
					 minimize or eliminate discharge into the VTA during rainfall events. Delay
					 application until rainfall has ended to improve infiltration and nutrient
					 uptake.
To maximize nutrient uptake, use warm and cool season
					 species in separate areas to ensure that plants are actively growing during
					 different times of the year.
Supplement water as necessary to maintain plants in a
					 condition suitable for the treatment purpose.
Consider suspension of application to treatment area when
					 weather conditions are not favorable for aerobic activity or when soil
					 temperatures are lower than 39° F. When soil temperatures are between
					 39° F and 50° F, consider reducing application rate and increasing
					 application period while maintaining a constant hydraulic loading rate.
Manage the VTA to maintain vegetative treatment
					 effectiveness throughout the growing season. Time the harvest of the VTA plants
					 so vegetation can regrow to a sufficient height to effectively filter effluent
					 late in the growing season.
Install a berm around the lower end of the VTA to contain
					 excess runoff that may occur.
Effluent from the VTA may be stored for land application,
					 recycled through the wastewater management system, or otherwise used in the
					 agricultural operation.
Install fences or other measures to exclude or minimize
					 access of the VTA to humans or animals.
Install a pumping system at the bottom of the VTA to either
					 recirculate the effluent to the top of the VTA or transfer to a waste storage
					 facility.
PLANS AND SPECIFICATIONS
Prepare plans and specifications that describe the
					 requirements for applying the practice to achieve its intended use. As a
					 minimum include:
Critical construction perimeters, necessary
						construction sequence, vegetation establishment requirements, retention area
						and level spreader mechanism requirements, associated practices and agronomic
						nutrient removal.
										Plan view showing the location of all components of
						the VTA.
										Details of the length, width, and slope of the
						treatment area to accomplish the planned purpose (length refers to flow length
						down the slope of the treatment area).
										Herbaceous species, seed selection, and seeding rates
						to accomplish the planned purpose
										Planting dates, care, and handling of the seed to
						ensure that planted materials have an acceptable rate of survival.
										Site preparation sufficient to establish and grow
						selected species.
OPERATION AND MAINTENANCE
Develop an operation and maintenance plan consistent with
					 the purposes of the practice, its intended life, safety requirements, and the
					 criteria for its design. Include the following items as appropriate:
Inspect and maintain retention and spreader area to
						ensure that sheet flow loading is maintained for the VTA.
										Inspect and repair treatment areas after storm events
						to address gullies, reseed disturbed areas, and prevent concentrated
						flow.
										Control undesired weed species, especially
						state-listed noxious weeds, and other pests that could inhibit proper
						functioning of the VTA.
										Exclude livestock from VTA.
										Apply supplemental nutrients and soil amendments as
						needed to maintain the desired species composition and stand density of
						herbaceous vegetation.
										Maintain or restore the treatment area as necessary
						by periodically grading or removing excess material when deposition jeopardizes
						its function. Reestablish herbaceous vegetation.
										Routinely dethatch or aerate a treatment area used
						for treating runoff from livestock holding areas in order to promote
						infiltration.
										Conduct maintenance activities only when the surface
						layer of the VTA is dry enough to prohibit compaction.
										Monitor all treatment areas to maintain optimal crop
						growth and environmental protection.
REFERENCES
USDA/NRCS, National Engineering Handbook, Part 651,
					 Agricultural Waste Management Field Handbook.
Koelsch, R., B. Kintzer, and D. Meyer. (ed.) 2006.
					 Vegetated Treatment Systems for Open Lot Runoff - A Collaborative Report. USDA,
					 NRCS.