The Land Steward’s Guide to Vineyard and Orchard Erosion Control
Sonoma County Department of Agriculture/Weights & Measures 133 Aviation Boulevard, Suite 110, Santa Rosa, CA 95403 Phone: (707) 565-2371 Fax: (707) 565-3850 Website: www.sonomacounty.ca.gov/AWM The Land Steward’s Guide to Vineyard and Orchard Erosion Control | 2
Acknowledgements This Guide was prepared by the Land Stewardship Division of the Sonoma County Department of Agriculture/Weights & Measures. It is a collective creation made possible by past and present staff whose contributions, insights, and perspectives have coalesced into The Land Steward’s Guide to Vineyard and Orchard Erosion Control. It is also a recompilation of existing material from numerous sources. We are deeply grateful to contributors, practitioners, and agencies who shared freely of their expertise and time. We thank the following reviewers for their thoughtful comments:
North Coast Regional Water Quality Control Board Sonoma Resource Conservation District Russian Riverkeeper LACO Associates University of California Cooperative Extension We gratefully acknowledge the previous works of these Resource Conservation Districts (RCD):
Sonoma RCD Goldridge RCD Napa County RCD RCD of Monterey County Marin RCD Upper Salinas – Las Tablas RCD This publication was supported by the U.S. Department of Agriculture’s (USDA) Agricultural Marketing Service through Grant 15-SCBGP-CA-0046. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of the USDA. Contact Sonoma County Department of Agriculture/Weights & Measures 133 Aviation Boulevard, Suite 110, Santa Rosa, CA 95403 Phone: (707) 565-2371 Fax: (707) 565-3850 Email: [email protected] Website: www.sonomacounty.ca.gov/AWM Disclaimer The information provided in this Guide is to assist vineyard and orchard operators on general principles of erosion control. Use of this information does not relieve the user of the obligation to comply with other federal, state, or local laws and regulations, or from liability for damages against the County of Sonoma and its contractors, and agree to indemnify the County of Sonoma and its contractors from and against any claims, suits, or liabilities arising out of activities undertaken based on this material. Cover photo: Jordan Vineyard and Winery, Healdsburg, CA.
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CONTENTS
Acknowledgements 2
Contact 2
Disclaimer 2
Introduction 7
How to Use this Guide 7
The Need for an Erosion Control Guide 7
Erosion of Livelihood 8
Farm Planning and Erosion Control 8
Developing an Erosion Control Plan 9
Chapter 1: General Principles of Erosion Control 13
The Erosion Process 13
Types of Erosion 13
Factors Influencing Erosion 14
Land Use and Land Management Practices 15
Typical Causes of Erosion 17
Chapter 2: Managing Surface Erosion from Cultivated Areas 21
Irrigation 21
Source Controls 22
Treatment Controls 26
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Chapter 3: Managing Sediment Delivery from Roads 29
Roads vs. Avenues 29
Hydrologic Connectivity of Roads 29
Determining the Drainage Break 30
Reducing Hydrologic Connectivity Along Road Networks 30
Road Maintenance Best Management Practices 31
Chapter 4: Managing Stormwater Runoff 36
Runoff Management 36
Best Management Practices for Stormwater 37
Chapter 5: Managing Gullies and Shallow Landslides 40
Gully Formation 40
Shallow Landslides 40
How to Prevent Gullies and Shallow Landslides 41
How to Repair Gullies and Shallow Landslides 42
Bioengineering for Gullies 43
Chapter 6: Pollutant Control – Managing Pesticides 44
Basic Integrated Pest Management Principles 44
Integrated Pest Management Considerations 45
Best Management Practices for Pesticides 45
Chapter 7: Pollutant Control – Managing Nutrients 48
Determining Nutrient Needs of the Plant 49
Fertigation 50
Storing and Mixing Fertilizers 50
Use of Backflow Prevention Devices 51
Establishing Vegetative Barriers to Filter Runoff 51
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Chapter 8: Winterization and Sustainable Maintenance 52
Winterization 52
Riparian Areas and Streams 52
Monitoring and Maintaining Best Management Practices 53
Vineyard Waste 53
Glossary 54
Additional Resources 57
References 61
Image Credits 65
Appendix 1: Best Management Practices Selection Matrix 70
Appendix 2: Surface Erosion Control 71
Cover Crop 72
Straw Wattle/Fiber Roll 75
Mulch 77
Filter Strip 79
Hedgerow 81
Erosion Control Blanket 82
Straw Bale Sediment Trap/Check Dam 84
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Appendix 3: Road Best Management Practices 86
Reshaping the Road Surface 87
Rolling Dip/Critical Dip 91
Waterbar 94
Water Deflector 97
Channel Drain 98
Trash Rack 99
Appendix 4: Stormwater Runoff 101
Vegetated Swale/Grassed Waterway 102
Retention Basin 106
Diversion Ditch 107
Silt Fence 110
Engineered Drainage 112
Energy Dissipater 113
Appendix 5: Gullies 115
Headcut Repair 116
Rock Check Dam 120
Brush Layering 122
Willow Wattle/Wall 124
Live Willow Staking 127
Typicals for Gully Repair 129
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Introduction The Sonoma County Department of Agriculture/Weights & Measures established the Land Stewardship Division (Division) in 2015 to effectively manage several Sonoma County environmental programs and to meet increasing environmental regulations. The Division administers the largest of these programs, the Vineyard/Orchard Erosion and Sediment Control Ordinance (VESCO), a permit process which serves to sustain the agricultural community while protecting water quality, natural resources, and protected species. Through VESCO, the Division is working to assist the agricultural community in meeting State Water Board waste discharge requirements by leveraging ongoing practices designed to protect water quality. To further these efforts, the Division has produced The Land Steward’s Guide to Vineyard and Orchard Erosion Control (Guide). The purpose of this Guide is two-fold: To help landowners and land managers understand erosion processes To describe practices for repairing small-scale erosion problems common to agriculture The Guide has compiled pre-existing information about approaches and techniques for managing runoff from farmland and is intended to be improved upon as science and experience develop better stewardship tools. This Guide is intended to serve as a tool for voluntary, self-implementation of soil and water conservation practices. It is not the intent of this Guide to provide design criteria for engineered structures. If needed, third-party technical assistance in planning and implementation is available through your local Resource Conservation District, the Natural Resources Conservation Service, University of California Cooperative Extension, or any private consulting firm.
How to Use this Guide To properly address runoff, a land manager must understand the fundamental processes of erosion, be able to correctly identify the source of the problem, and then select appropriate repairs. The Guide is designed to assist you with this methodology. Each chapter will cover important information to help you understand the source of your erosion. The appendices will assist in deciding how to effectively rectify the problem, maintain it, and achieve maximum effectiveness.
The Need for an Erosion Control Guide Farms no longer have just a street address; they now have a watershed address. A watershed address represents the growers’ responsibility for eliminating offsite movement of soil, chemicals, and pathogens, therefore eliminating impacts on downstream water bodies, groundwater, and water users. Growers must understand that their farming decisions affect others in the watershed. There are numerous and serious environmental and economic costs of erosion. Erosion problems can include water pollution, loss of soil quality, increased flooding, degradation of habitat and loss of species, impairment of stream ecosystems, decreased groundwater storage, release of carbon, slope failures, and damage to downstream lands and properties, including the time and costs associated with addressing these issues.
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In addition to the harmful environmental impacts, soil erosion takes a huge toll on local and downstream economies. Accelerated accumulation of sedimentation in water impoundments and infrastructure poses unanticipated economic burdens necessitating costly cleanup and dredging programs. For the purposes of this Guide, however, it is the agricultural costs of erosion which warrant attention and action.
Erosion of Livelihood Soil is one of the most critical resources on earth. As natural processes produce only one inch of soil every 500 ENVIRONMENTAL COSTS OF EROSION to 1,000 years, it is also a limited resource which, like Loss of hydrologic and ecosystem function. water, can be depleted and polluted. Initially, it is Loss of habitat. agricultural topsoil which is eroded. Topsoil, laden with the nutrients plants need for growth and the biological Deterioration of water quality. processes needed for health, is being lost at Increased flooding. unprecedented rates, leaving severly degraded and dead soils as the basis for our food production. The loss of soil ECONOMIC COSTS OF EROSION health poses economic burdens and serious crop quality Loss of topsoil. issues to agricultural managers. Dredging reservoirs, lakes, bays, and From an agricultural perspective, a healthy soil ecosystem estuaries. gives crops their vitality, character and quality. Caring for Undermining buildings, bridges, and roads soil is a long-term investment and is essential for the long along creeks. life and productivity of agriculture. Soil protection and Replacement of lost soil nutrients. regeneration is essential to your survival as growers and to all of us as a civilization. Removal of sediment from infrastructure.
Farm Planning and Erosion Control AGRICULTURAL COSTS OF EROSION Regional Water Quality Control Boards (RWQCBs) Reduction in crop yields. throughout California have identified pollutants from Loss of soil nutrients, organic matter, and vineyard and orchard stormwater runoff as detrimental to biodiversity. stream habitats. These RWQCBs are currently developing Increased costs of fertilizers and or have already adopted new General Waste Discharge amendments. Requirements and Waivers of Waste Discharge Increased loss of soil. Requirements (WDRs) for vineyards and orchards to reduce their environmental impacts. These new permits Decreased infiltration rate. will require vineyard and orchard operators to develop and Reduction in water holding capacity. follow Farm Water Quality Plans (Conservation Plans). Preparation of these Conservation Plans will require operators to identify contributing sources of sediment, and nutrient and pesticide pollution, and describe actions to eliminate them, including documented use of Best Management Practices (BMPs).
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Operators will be required to complete a Conservation Plan for each of their sites to demonstrate compliance with the WDRs. The practices described in this document are intended to assist operators in developing and implementing portions of these plans to help comply with WDRs. A comprehensive farm plan for any agricultural operation requires that plans consider site-specific factors such as topography, soils, hydrology, weather, climate, management practices, environmental impacts, regulations, economics, and human aspects. This site-specific farming plan also includes an Erosion Control Plan (ECP) to manage the erosive factors onsite.
Developing an Erosion Control Plan On average, a vineyard on 10% slope with a 200 foot slope length can lose more than five tons of soil per acre per year (Martinson). Successful minimization of this amount of soil erosion can be achieved by implementing an ECP utilizing erosion and sediment control BMPs to prevent soil movement and soil loss. Besides managing erosion, BMPs can enhance project aesthetics, reduce complaints and regulatory agency fines, and eliminate appreciable damage to offsite receiving channels, properties, natural resources, and surface water bodies. Most importantly, an ECP will help retain the topsoil on your property. An ECP can assist you in identifying the erosion sources and potential locations of sediment discharge that could affect the quality of stormwater and irrigation water discharges off your property. The ECP will help you in documenting the management practices you have or plan to implement based on the potential for sediment discharge and erosion from your land. The ECP development must adequately address your operation and must be implemented to address site-specific conditions in order to meet water quality requirements of the Water Boards. Erosion Control Plan Principles BASIC EROSION PREVENTION RULES The most effective management strategy of an ECP is to implement practices that minimize erosion and transport Protect exposed soil. at the source. The secondary strategy is to incorporate Do not concentrate flows; decrease flow practices that encourage deposition of eroded sediment volume and velocity. prior to leaving the site. Decrease deposition offsite. Controlling water flow through and out of your vineyard Retain as much existing vegetation as will greatly reduce transport of soil and contaminants possible. offsite and will preserve your vineyard’s productivity. Encourage infiltration.
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Source Control vs. Treatment Control SOURCE CONTROLS In general, source controls are methods to decrease runoff by protecting the soil surface. Prevention at the Cover crops. source is the simplest and most cost effective technique Mulching. for managing erosion and source controls are the most Erosion control blankets. common BMPs. The only true source control is vegetation, such as cover crops, whose roots anchor the soil and protect it from erosive rainfall impacts. TREATMENT CONTROLS Treatment control BMPs are concerned with removing Vegetated filter strips. pollutants from runoff and preventing their introduction Hedgerows. to the environment. These controls largely use physical Silt fencing. processes to remove suspended particles from runoff. Swales/grassy waterways. Vegetated filter strips are a good example of treatment Straw wattles. control BMPs. Straw bales. An ECP will generally include a suite of source control and Diversion ditches. treatment control BMPs to address site-specific erosion problems. Retention basins. Erosion Control Plan General Guidelines While developing an ECP, incorporate a set of INDICATORS OF SOIL EROSION management objectives for a comprehensive plan that Bare soil. includes strategies that: Road erosion. Assess existing soil conditions and runoff patterns. Exposed roots. Develop a vineyard or orchard layout that minimizes erosion. Small benches of soil behind obstacles. Manage the vineyard or orchard floor to maintain Surface soil crusts. protective vegetative cover. Silty water, sediment deposits. Coordinate efforts to control sources of runoff, Deposits of soil at slope changes. sediment, and erosion with neighboring landowners. Decrease thickness of topsoil. Exposed subsoil. Manage roads and non-cropped areas to reduce runoff and prevent erosion. Visible rills, gullies. Retain eroded sediment and runoff before it leaves Poor plant growth. the property. Algal blooms. Prevent erosion from irrigation practices. Evaluate, adapt, and maintain management goals and recommended practices.
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For BMPs to be effective in controlling nonpoint source pollution, they must be properly designed, sited, installed, and maintained. Proper design includes making sure the selected BMP will achieve the desired result. The BMP should be sited in the best location to achieve maximum pollutant removal and installed in such a manner that it will function properly. BMP structures which are not maintained will most certainly fail. Therefore, maintenance is critical to BMP effectiveness. Generally, a site-specific suite of compatible BMPs working together has proven to be most successful at managing erosion and sedimentation. Throughout the ECP process, keep in mind that prevention of the conditions that lead to runoff and erosion is always cheaper than fixing the physical problems caused by runoff and erosion after the fact. There are numerous templates available to develop an ECP. As always, retain the services of a professional when contemplating engineered solutions. When applied to your operation, the following process will assist you in development and implementation of an effective suite of BMPs. Site Evaluation and BMP Selection Process STEP 1 - ORIENTATION •What does this mean and why does it matter? •Learn about erosion and BMPs.
STEP 2 - EXISTING SYSTEMS •What am I doing and using now? •Inventory and map property and structures, review practices.
STEP 3 - SITE AUDIT •What is working right and what needs to be fixed? •Evaluate site conditions and determine erosional features, note on map.
STEP 4 - SELECT BMPS •How do I fix it? •Develop solutions, schedule repairs, conduct trainings.
STEP 5 - PERMIT RESEARCH •Do I need a permit? Which agencies should I consult? •County/local agencies, state agencies, and federal agencies.
STEP 6 - PREPARE PLAN •Put it all together. •Create timeline to address all items froms steps 3, 4, and 5.
STEP 7 - DOCUMENT SUCCESSES •Prove the plan is working. •Adaptive management: maintain inspection log and record of BMP successes, failures, and changes in management.
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Agricultural operators can better assess and remediate erosion problems armed with a thorough understanding of the process of erosion, professional technical experience, and good judgment. The following chapters will address management measures associated with specific areas of agricultural erosion.
Civilization’s survival depends on treating soil as an investment, as a valuable inheritance, rather than a commodity – as something other than dirt. - D. Montgomery
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Chapter 1: General Principles of Erosion Control The Erosion Process Broadly defined, erosion is a process in which soil particles or other dissolved material are detached from one location and transported and deposited in another location. For purposes of this Guide, erosion refers to an accelerated loss of soil as a result of agricultural activities, in excess of accepted rates of natural soil formation. Agricultural activities such as irrigation, removal of vegetation, and soil disturbance, if not carefully managed, can allow for soil movement, transport and deposition.
Types of Erosion Erosion can be classified into five main types in increasing levels of severity: splash erosion, sheet erosion, rill erosion, gully erosion, and landslide erosion. As water increases in volume and velocity, erosion types grow larger and more difficult and complex to manage. Splash erosion is the first and least severe stage in the soil erosion process and begins with raindrops impacting the unprotected surface of the soil and ejecting or splashing soil particles away from the impact area (rainsplash). If the surrounding soil is unvegetated or sparsely vegetated, saturated, and/or rainfall rate exceeds infiltration rate, surface runoff can occur over large and/or sloped areas, leading to sheet erosion. Sheet erosion occurs when surface runoff has sufficient flow energy to move loosened soil particles by overland flow, sometimes resulting in the loss of a tremendous amount of rich topsoil. Sheet erosion commonly occurs on tilled fields having poorly consolidated soil material with scant vegetative cover. Rill erosion occurs when surface runoff continues unabated across unprotected slopes. As water runs downhill, it gains velocity and force, concentrating into small eroding channels called rills. Gully erosion occurs when uncontrolled rill erosion is allowed to carve deep branching channels in topsoil. Landslide erosion is a mass movement of soil off of unstable areas. Agricultural activities in areas of instability can exacerbate unstable conditions, leading to mass wasting.
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These various types of erosion are driven by two basic physical properties: gravity and momentum. Water naturally seeks the lowest point and increases in speed as it moves downslope. Thus, runoff velocity increases as slope increases. Conversely, as slopes decrease, runoff velocity decreases and runoff volume increases. Concentrated volumes of moving water have tremendous amounts of power and can be difficult to control.
Factors Influencing Erosion All of the following factors are site-specific and, considered collectively, will determine the erosion potential of each property. Precipitation Rainfall amounts and rainfall energy directly affect erosion rates. The Mediterranean climate in California is particularly prone to soil water erosion because of long dry periods followed by heavy bursts of intense precipitation on steep slopes with fragile soils. Water that falls on the land has only two places to go. It can percolate into the soil or run over the soil surface. In big storms that produce intense rainfall, much or most of the rainfall flows over the soil, even with intact drainage systems. Such intense storm events cause serious erosion to unprotected, unvegetated soils. Topography Water seeks the path of least resistance. During and after large storm events, those pathways are easy to identify by observing the flow of runoff and where sediments are deposited. The topography of the site, particularly its slope, will generally determine the natural drainage pattern of runoff. Without careful forethought, any hydromodification of naturally occurring drainage patterns can significantly increase the erosion potential at the site. Vegetation Vegetation anchors soil particles and provides a buffer against the erosive effects of rainsplash. A deeply rooted mix of understory and overstory cover crop plants provide a multitude of benefits, the most important being erosion prevention and filtration of sediments. Retention of residual dry matter also provides protection and inhibits soil movement.
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Soil Type Healthy soils in natural systems increase infiltration, minimize rainsplash, and reduce surface runoff. There are over 70,000 different soil types identified, each with its own unique set of characteristics and erosiveness. And each agricultural site may have numerous soil types. It is extremely important to understand your soil types and how each type responds to water movement and erosion.
Land Use and Land Management Practices Agricultural operations, such as degree of tillage and management of equipment, can compound the effects of soil disturbance which can add to erosion problems. Soil Compaction Healthy soils are well-aggregated. Aggregates are groups of soil particles that bind together strongly to provide pore space for the retention and exchange of air, water, and nutrients. Soil compaction refers to the deterioration of these aggregates due to natural and manmade factors. Without proper pore space, water and air movement through the soil is restricted and the plants are left with a reduced capacity to thrive. In addition, soil compaction has other negative effects, including reducing infiltration and groundwater recharge, concentration of nutrients and pesticides, and increasing quantities of stormwater runoff. The weight of heavy equipment, frequent traffic, and over- saturation of soils can lead to soil compaction. Soils cannot entirely resist the pressure imposed by heavy equipment and tillage implements; however, some soils are more susceptible to compaction. Again, it is important to know your soils. Considerations to reduce soil compaction include lowering field traffic, retaining/adding organic matter, modifying tillage operations, and avoidance of wet or poorly drained soils. Field Traffic Tractors, implements, livestock, and humans can compact soil when traveling across a field. While the severity of this compaction depends on many factors, one pass over a field under poor conditions can cause significant damage. In any given situation, the first pass of a wheel causes 80% of the potential compaction. Equipment with wider tires or tracks helps to spread the weight over a larger area and reduce compaction. Having a central staging area for parking cars and equipment will reduce traffic in the field.
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Tillage Operations and Equipment Tillage can create or alleviate soil compaction. By their nature, tillage operations break up soil into smaller particles. While that can aid in reducing compaction, excessive tillage without intensive management, may pulverize soil aggregates, destroying the structure that provides desirable pore space. Tillage also causes oxidation of carbon and destruction of mycorrhizal fungi, the microbes responsible for plant vigor and symbiotic ecosystem services. Wet or Poorly Drained Soils It is critical not to work or drive on soil when it is too wet. When soil is wet, the bonds holding aggregates together are weak and pliable, so they can be more easily destroyed, resulting in compaction. Most operators recognize that driving on a wet field leaves ruts – a visible sign of compaction. The wetter the soil, the deeper the rut will be, and the more the soil compacts.
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Typical Causes of Erosion Erosion can also be caused by other forces such as wind, ice, and tides. For agricultural operations, this Guide will focus on the following typical causes of erosion normally associated with agricultural activities. Any of the following human activities can cause erosion. If two or more elements are present, erosion will increase significantly. Disturbing Existing Drainage Patterns
BEFORE AFTER
Natural drainage flow stabilized over time. Disturbance of existing drainage flow.
Good soil infiltration/percolation. Drainage course altered, flows concentrated.
Reduced soil infiltration/percolation.
Grading or Disturbance of Sloping Land
BEFORE AFTER Unaltered slopes, covered with vegetation Construction on slopes can result in remain stable, buffering surface flow, accelerated runoff and may increase potential permitting excellent soil infiltration. for gullying, slope failure, and downstream Good soil infiltration/percolation. erosion.
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Removing Existing Native Vegetation
BEFORE AFTER Soil protected by native vegetation. Removal of vegetation by grading or other Vegetation roots and coverage promotes means removes protective roots and infiltration and reduces runoff. coverage, thus increasing surface flow and greatly reducing soil infiltration/percolation. Good soil infiltration/percolation.
Disturbance of Erosive Soils
BEFORE AFTER
Well vegetated erosive soils will remain stable Ground disturbance or removal of native during storms. vegetation accelerates erosion of all soils, but Roots and foliage of vegetation provide the effect is more dramatic on highly erosive soils. coverage and soil protection, significantly reducing surface flow and greatly increasing soil infiltration/percolation.
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Improperly Designed Roads
BEFORE AFTER Before road construction or other Improperly designed roads can concentrate development, upland drainage forms sheet drainage. flow until it reaches natural channels. Natural sheet flow is interrupted and flows This condition reduces erosion by spreading are often directed to inadequate drainage out flows instead of concentrating them. ditches which can quickly erode, creating deeper and wider rills and gullies. Soil infiltration is reduced. Construction of Impermeable Surfaces
BEFORE AFTER Soil, covered with vegetation, buffers against Impermeable surfaces result in increased rainfall and reduces surface flow, permitting runoff and increased potential for good soil infiltration. downstream erosion. Cumulative impacts of increased runoff can be significant.
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Improper Use of Vehicles
BEFORE AFTER Soil covered with vegetation buffers against Unmanaged vehicle use can trample rainfall and reduces surface flow. vegetation, compact soil, create ruts, and over time, cause erosion. This natural state is stable. Unauthorized vehicles in streams and river channels add oils and other contaminants.
Improper Construction of Erosion Control Structures
BEFORE AFTER
Poor use of silt fences in small drainage or During storms, improperly used silt fences can channel. cause erosion. Better solution: use proper erosion control Silt fences or improperly placed straw bales in blankets in combination with planting within channel or drainage ditch will accelerate ditch or channel. erosion around and under the silt fence or bales. NEVER use erosion control devices improperly.
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Chapter 2: Managing Surface Erosion from Cultivated Areas Soil is a living ecosystem with complex interactions between soil, water, microbes, mycorrhizae, and other plant and animal life. This web of interactions, when undisturbed, provides an environment that requires few inputs, yet continually yields productive plants. When soils are disturbed, these interactions are broken, and soil loses its ability to perform such functions as infiltration and water holding capacity, recycling of nutrients and minerals, loss of organic matter (particularly carbon), and decreased oxygenation. Good management measures can restore some of these losses. Maintaining good soil organic matter levels helps keep topsoil in place. A soil with more organic matter usually has better structure. Good soil structure allows more water to infiltrate the soil instead of running off the field, taking topsoil with it. Surface residues, such as leaf litter or mowed cover crops, are also important. They leave a rougher soil surface which helps to intercept rainfall runoff and slow down water running over the surface. Leaving surface residual matter is especially important if tilling is a part of your management program.
Irrigation Irrigation practices can contribute to erosional problems. Proper irrigation scheduling to effectively and efficiently deliver water to the crop allows the manager to conserve water resources, minimize or eliminate erosion, and also realize economic incentives of less water usage. The following management strategies, developed on a site- specific basis, can assist in controlling erosion and sedimentation from cultivated areas.
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Source Controls Conservation Tillage Conservation tillage is a generic term that covers any tillage system that reduces losses of soil and water compared with conventional tillage. Conservation tillage is an increasingly common practice in modern agriculture as part of the transition to sustainable or regenerative organic farming. While conventional tillage reorders the entire soil profile, conservation tillage strives to decrease soil disturbance, retain existing vegetation and preserve soil dynamics. Conservation tillage includes no-till (zero- till), minimum till, and reduced till operations. Researchers have found that no-till systems are very effective at preventing soil erosion, especially after heavy rains by maintaining adequate vegetation. Besides reducing erosion, keeping residues on the soil surface also increases water holding capacity, decreases soil temperature, assists in retaining soil carbon, maintains symbiotic mycorrhizae, and protects soil aggregates, all important to health soils. Overall, runoff and soil loss were almost 40% higher under conventional tillage conditions. Additional information regarding conservation tillage can be found at http://extension.psu.edu/plants/crops/soil- management/conservation-tillage. Cover Crops Cover crops serve several important functions in a vineyard or orchard setting. Cover crops are plants that are seeded between vine rows, allowed to establish, and can be mowed, rototilled, or left standing, depending on the beneficial use to which they were prescribed. Maintaining adequate cover crops is one of the simplest and most cost effective methods to reduce surface erosion. Cover crops can help vineyard and orchard operators by performing a number of important tasks: slowing erosion; improving soil health, diversity, and soil organisms; controlling weeds; enhancing nutrient and moisture availability; increasing soil carbon; controlling many pests; and innumerable other benefits to your operation. Because their benefits accumulate over the long-term, cover crops are modest investments which continue to reap rewards years after their installation. There are many types of cover crops including perennial, annual, fast growing, slow growing, overstory, understory, grasses, and forbs. Determining the mix for your operation depends on current and future preferred conditions. A multitude of different cover crop mixes are available containing various species that have the potential to provide a variety of benefits to operators. When selecting a cover crop mix, select a mix that has both tall, fast growing plants for overstory protection and leafy, low growing plants for understory protection. For additional information, watch Discover the Cover at www.youtube.com/watch?v=VHMCJSxQAgo.
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The Importance of Cover Crops
PROTECTING SOIL FROM EROSION
•Foliage of cover crops reduces the velocity of raindrops before they hit the soil surface. The roots of the cover crops bind soil particles together, improving soil structure and water penetration, while anchoring the soil.
IMPROVING SOIL TILTH
•Initially, cover crop roots help aggregate soil particles as fine roots penetrate deep into the soil profile. Cover crops with large tap roots help to create macro pores when the plants die and a void is left from decomposing roots, increasing aeration, water infiltration, and drainage in the soil profile.
IMPROVE AIR AND WATER QUALITY
•Water quality laws require that runoff is free of silt and excess nutrients. Nitrogen formed by legumes is less mobile than soluble nitrogen fertilizers. Cover crops assimilate and stabilize free nutrients in the soil during periods of high rainfall. During dry periods of the year, cover crops help reduce dust, improving air quality. This also helps to reduce the problem of mite infestations, which intensify under dusty conditions.
IMPROVE SOIL FERTILITY
•Besides increasing soil nitrogen, decomposed cover crops increase the soil cation exchange capacity, increasing the soil’s ability to hold and exchange nutrients.
ENHANCE BIOLOGICAL DIVERSITY IN THE ROOT ZONE
•Organic matter is a food source for macro- and microorganisms. Increased biological activity occurs in the soil after the incorporation of organic matter from cover crops. Particularly noteworthy are increases in earthworm populations, soil microbial populations, and mycorrhizal fungi, all good indicators of soil health and improved physical conditions.
HABITAT FOR BENEFICIAL INSECTS
•Cover crops can provide habitat and food for beneficial insects at different stages of their life cycle and help control harmful insects and mites. Growers report reduced leafhopper and mite problems when cover crops are planted in lieu of conventional insecticide applications.
PROVIDE STABLE AREAS FOR HARVEST AND CULTURAL OPERATIONS
•When no-till, sod-forming cover crops are planted, the resulting firmer footing makes vineyard and orchard operations during wet weather more feasible. This can enable harvest, pruning, and spraying during inclement weather.
REGULATE VINE GROWTH
•Cover crops can be used to both invigorate vines (augmenting soil nitrogen from nitrogen-fixing legumes) and devigorate vines (root competition from non-legumes with the vines for nutrients and water). McGourty, 2004
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Mulching Mulching is an effective erosion control technique and is best used in conjunction with cover crops. Mulch is a layer of material applied to the surface of exposed soil used to conserve moisture, improve fertility and health of soil, reduce weed growth, and most importantly in terms of erosion control, provide a protective blanket over bare soil. Mulches are usually, but not exclusively, organic in nature and include straw and wood chips. Mulches can be used in conjunction with cover crops, helping to prevent seeds from washing away and providing a better environment for germination, allowing newly planted seed to become established. Mulches used for ground cover vary in cost, application procedures, and appropriate conditions of use. The two basic classes of mulch include loose mulch and hydraulically applied mulches known as hydromulches. Loose Mulches Straw and wood chips are the most common materials applied as loose mulch. Straw is usually the least expensive mulch available and large areas can be covered with straw using commercial blowers, which break up straw bales and blow the straw onto the soil. Applying straw by hand is also effective, but more expensive due to labor costs. Straw mulch is most effective when applied on modest slopes at a rate of four tons per acre and lasts about three months, usually enough time to establish permanent stabilizing vegetation. Because straw is lightweight, it is easily blown away. Organic tackifiers, compounds used to increase the stickiness of loose mulch, can help reduce this problem. Crimping, a technique using a tractor to partially punch the straw into bare soil, can also help anchor loose mulch to the surface, if soil moisture is available. Wood chips, or shredded woody materials, are ideal for mulching around established vegetation, but should be applied only where no permanent vegetation is planned. As this high-carbon material decomposes, it can remove plant nutrients from the soil through microbial processes, resulting in lower soil fertility.
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Hydromulches Hydroseeding, or hydraulic mulch seeding, is a planting process that uses a slurry of seed and mulch. It is often used on construction sites, but can be effective on any site that would benefit from an alternative process of broadcasting or sowing dry seed and covering with loose mulch. This technique can protect a relatively large area in a very short period of time. Results are quick with high germination rates producing grass growth in about a week. Adding fiber mulch, such as straw, accelerates the growing process by maintaining moisture around the seeds, increasing the rate of germination while simultaneously protecting bare soil from erosion. The hydroseeding slurry is transported in a tank and sprayed over prepared ground. The slurry often has other ingredients including fertilizer, tackifying agents, fiber mulch, and green dye. Manufactured Products There are a wide variety of manufactured products available to protect exposed soils and help manage runoff. These products are made up of a variety of materials such as straw, jute, coconut coir fiber, recycled plastics, etc., and are designed to solve a wide range of erosion issues. For protection of wildlife and ease of maintenance, biodegradable products are recommended. The chief advantage of these products is their uniformity, durability, ease of installation, and longevity. Manufactured products function best when installed properly. Consult manufacturer’s directions for suitability, proper application, and longevity of specific manufactured products. Erosion Control Blankets Erosion control blankets (ECBs) vary widely in composition, price, and suitability. ECBs are a woven product that is anchored to the surface of the soil with metal staples or wooden stakes. ECBs are dimensionally stable, reinforced rolled products made from a variety of organic and synthetic materials, including straw, coconut (coir), and polypropylene nettings. Biodegradable materials are recommended. It is critical that ECBs are installed properly. In general, ECBs are more expensive and labor-intensive to install compared to straw mulch and are more comparable to the costs of hydromulching. Important factors such as slope ratio, duration of use, biodegradability, cost, and effectiveness should be taken into consideration when selecting an appropriate ECB. During installation, good contact between the ECB and soil surface is important to reduce soil bridging and washouts under the ECB. Correct installation is important for long-term erosion control and vegetative establishment. It is critical to make sure the blanket is flush with the soil surface and the top of the blanket is tucked in and the edges are overlapped properly.
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Treatment Controls When it is not possible to prevent 100% of sediments from the farmed areas from entering runoff, an alternative option is to “treat” the runoff to ensure that it is not transported off the property. This is accomplished through the use of perimeter controls including vegetated filter strips, hedgerows, silt fencing, and straw wattles. Vegetated Filter Strips Many of the same species used for cover crops can also be used to establish a vegetated filter strip. Filter strips are gently sloping, densely vegetated areas that filter, slow, and infiltrate sheet flowing stormwater. The erosional benefits of filter strips include capture of pollutants and settling of sediments. The vegetation in filter strips must be dense and healthy to accomplish these benefits. Typically, filter strips are composed of thick, low growing, tough, perennial grasses that can be mowed in the summer but revive with the first fall rains. Trees, shrubs, and native vegetation may be added for aesthetic value. Vineyard avenues can be easily converted to vegetated filter strips. This can be useful on a hillside because the avenues between vineyard blocks can now be used to slow and filter runoff. It is also beneficial for avenues along waterways and drainage ditches. Hedgerows Hedgerows consist of trees, shrubs, grasses, and forbs that surround farm fields. Their many benefits include enhanced weed control, water quality protection, carbon sequestration, erosion control, biodiversity, and increased beneficial insect activity. Like filter strips, they act as a buffer to capture pollutants and allow runoff to infiltrate. Establishing hedgerows requires long-term planning and care to ensure success. This effort includes developing a farm plan; selecting, analyzing, designing, and preparing the site for planting; choosing appropriate plants; and initiating a plan for weed and rodent control. Once established, hedgerows require minimal maintenance while providing multiple benefits.
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Silt Fencing A silt fence is a temporary sediment control device used to protect water quality from sediment in stormwater runoff. Silt fences are made of filter fabric, attached to supporting poles, and trenched into the soil along the contour of the slope. The silt fence temporarily detains sediment-laden water, allowing clean water to pass through while keeping sedimentation behind the fence. Generally used as perimeter control, silt fences are most effective at the bottom of the hill to catch any sediment that might have escaped through other erosion control measures placed uphill. It is important that silt fencing be installed on contour lines to avoid directing or channeling stormwater runoff. Proper installation according to the guidelines is crucial to sediment control success. Maintenance of silt fences before and after every major storm is critical. Straw Wattles Straw wattles, also known as fiber rolls or straw logs, are very effective at moderating surface runoff. A straw wattle consists of wood excelsior, rice or wheat straw, or coconut fibers and is rolled or bound into a tight tubular roll and placed on the toe and face of slopes. Properly installed, they play a number of useful roles by intercepting runoff, reducing its flow velocity, releasing the runoff as sheet flow, and removing sediment from the runoff. Straw wattles may also be used for inlet protection on drainage systems and as check dams under certain situations. There are a wide variety of straw wattle types; some are designed to be reused, while others are designed to biodegrade. In agriculture, biodegradable materials are recommended. Similar to silt fencing, straw wattles have the advantage of being semi-permanent meaning they can be left in place and will continue to function as they decompose, providing benefits beyond the initial season. Besides perimeter control, straw wattles can be used on roads as waterbars or, in some cases, in channels such as swales to slow flows.
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It is essential that straw wattles be placed properly on the site and installed correctly in order to ensure the success of the product. Straw wattles are designed for low surface flows. While they can work well on streambanks, straw wattles should not be used in areas of high water flow. On slopes, wattles should be installed along contours and trenched in. Installation should follow the manufacturer’s recommendations or according to the guidelines in Appendix 2: Surface Erosion Control. Perimeter control should be in place whenever soil is exposed. Vegetated filter strips, hedgerows, silt fencing, and straw wattles are all examples of robust perimeter control.
Straw Bales Straw bales can be used as sediment traps and check dams within disturbed areas and with small drainages. A straw bale sediment trap is a temporary catch basin consisting of a row or more of entrenched and anchored straw bales. Straw bales function by decreasing water velocity and detaining sediment-laden surface runoff long enough for coarser sediments to deposit behind the bales. The decreased water velocity also reduces downcutting in ephemeral channels. There are a number of planning considerations which should be reviewed prior to installation of straw bales.
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Chapter 3: Managing Sediment Delivery from Roads Roads can be a major source of erosion and sedimentation on farmed lands. Essential for farming, roads are corridors not only for vehicles and wildlife, but also for water and sediment. Gravel and native surfaced roads on upland landscapes are significant sources of runoff and sediment to the riparian environment. Compacted road surfaces increase the rate of runoff and road cuts can intercept and bring groundwater to the surface. Culverts at stream crossings can plug, causing erosion of the fill or formation of gullies from diverted streamflow. Roads can adversely impact streams, water quality, and aquatic habitat in several ways, including erosion and sediment delivery, altering hillslope and stream hydrology, and discharging pollutants to streams and water bodies.
Roads vs. Avenues The road network in existing vineyards and orchards can be categorized into two major types: access roads and avenues. Access roads are used to convey workers and equipment to the growing grounds, while avenues are used to maneuver around the growing grounds. Access roads are generally rocked or paved and are often used year round as driveways. In contrast, avenues are usually dirt or grass and are typically used only during growing and harvest periods. Access roads are usually engineered and often include drainage features such as roadside ditches, stream crossings, and culverts, while avenues typically follow the contours of the blocks they transverse.
Hydrologic Connectivity of Roads Roads and their drainage systems are frequently linked with the natural stream network and surface waters of a watershed through surface runoff from both ditches and road surfaces. These roads and road segments are termed “hydrologically connected roads” and the degree of connectedness fluctuates depending on the magnitude of the rainfall during a storm event and how much runoff is produced. A hydrologically connected road or road segment has been defined as any road segment that has a continuous surface flow path to a natural stream channel during a storm event. Road connectivity is typically reported as the total road length or percent of road network that is documented as “connected.” There are many ways that a road can be hydrologically connected to the local stream network. Examples include: Inboard ditches along roadsides that capture hillslope drainage and can route that flow, as well as transported sediments, to the nearest stream crossing on that road. Road surface flows that cause shallow rilling and deliver runoff and sediments to streams. Undirected stormwater runoff from the road surface which can reach a waterway with continuous flow. All of these examples define hydrologically connected roads.
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Determining the Drainage Break Once a hydrologic connection is identified, it is important to determine how much road length is connected to that point. The length of road draining toward the site, either from one or both sides of the point of connection, needs to be measured to determine the total connected road length. The measurement will extend to a point where the slope of the road changes and begins to drain in the opposite direction, away from the hydrologic connection point. This point is known as the drainage break. The road length can be measured by walking up the road to the drainage break while counting steps and multiplying by the length of a step, by using a GPS device to map and measure the route, or by marking the drainage break on a map and using an accurate scale bar to measure the hydrologically connected road length. This exercise needs to be repeated from each hydrologically connected point along a road network. When beginning to map out hydrologic connectivity of a road network, a good rule of thumb is to start from the highest point of the road, the top of the hill, and work downslope. This way, the path of the water is followed as it travels downslope and it can be easier to comprehend the route it takes. Another option is to conduct this assessment during winter rains when the water flow path can actually be seen. If there is a low spot in the road and the drainage exiting the road does not connect to any stream, there is no hydrologic connectivity.
Reducing Hydrologic Connectivity Along Road Networks The key to successful road drainage is to get water off road surfaces as quickly as possible. The less area and time water has to accumulate and coalesce on or along a road, the less opportunity it has to concentrate into large flow volumes and gain erosive force causing erosion damage. The three most important rules for accommodating road runoff are:
Drain and disperse water off the road surface as quickly as possible so it cannot begin rilling the road surface or deepening the inboard ditch. Convey runoff away from the road frequently to prevent large velocity, erosive flows from developing that can create problems at the outfall. Direct runoff to safe locations away from watercourses, private property, and unstable areas.
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It is important to keep these rules in mind when designing, building, and maintaining the structures in a road network. The use and correct placement of drainage structures such as rolling dips, diversion ditches, insloping, outsloping, inboard ditches, ditch relief culverts, waterbars, and stream culverts are worth the initial cost of installation. Modifications and repairs are more costly than the original installation, and damage to the land and nearby streams may be irreversible.
Road Maintenance Best Management Practices Plug Potential Assessing whether or not a culvert installed on a road has a high likelihood to plug can take a practiced eye. It is worth taking the time, however, to conduct such an assessment on a road network so measures can be taken to prevent severe damage that can result from a plugged culvert. A culvert on a road that is designed to transfer streamflow safely through a road bed is a vital part of transportation infrastructure. A culvert that becomes plugged or partially plugged can cause streamflow to back up on the uphill side of a road. If this water gets high enough to enter the roadway, the water can either divert down the road or exit across the road causing serious damage wherever it exits the road surface. When assessing a culvert for plug potential, it is important to get off the road to a place with a good view of the culvert inlet and surrounding area. Some things to note when assessing a culvert:
Is the culvert inlet completely or partially buried? If so, the culvert inlet is in need of cleaning. Pull all sediment and organic debris out of the pipe inlet and clear the area around the inlet. Is the rust or silt line along the inside of the culvert higher than the halfway point? If so, the culvert may be undersized. This evidence shows that the streamflow regularly fills the culvert to the halfway point or beyond which likely means the culvert will not be able to handle significant storm flows. Is there evidence of scour or rafted debris above or around the culvert inlet? If so, this means the stream overwhelmed the capacity of the pipe inlet at some point and either eroded the area above or around the inlet or deposited woody material at that point. Is the pipe inlet crushed or flattened? If the pipe inlet appears to have a decreased capacity for any reason, make sure it is cleared or pulled back open to ensure it can take its full potential of flow.
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There are several things to consider when deciding the appropriate techniques to employ when attempting to decrease culvert plug potential. The primary considerations are time and cost. Replacing an inadequate culvert is expensive and time consuming when the required permitting is considered, but it is also the most effective way to deal with an issue and one that can save considerable time and money in the long run. The quickest and cheapest way to decrease plug potential is to leave the existing potentially inadequate culvert and apply BMPs at and around the pipe inlet.
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Trash Rack The simplest and most effective method to decrease culvert plug potential is the addition of a trash rack to the culvert inlet. This consists of a single post placed in line with the center of the culvert, ideally at an equal distance as the diameter of the culvert. For example, a 24 inch diameter culvert will have the post placed 24 inches in front of the inlet center point. This will act to turn floating sticks and debris to align with the culvert to pass through the inlet or large pieces will raft and settle between the post and the edge of the culvert inlet but maintain a gap in front of the inlet for water to pass through. Do not place a screen or grate immediately over the culvert inlet. This acts as a debris net and will plug your culvert very quickly. Remember that trash racks require maintenance and should be cleaned before and after every storm event. Other than adding a trash rack to the culvert inlet, the best practices are to simply maintain a clean and open inlet and outlet. Make sure that neither side of the culvert is crushed or plugged. Look into the pipe for signs that it is becoming rusted through or separated in the middle. It is recommended to make these checks part of a routine inspection of a road network. These are simple checks that can prevent significant damage to roads and doing so before and after every significant storm event can make a big difference. Diversion Potential Diversion potential is a term used to describe a stream crossing on a road that has the potential to divert the stream out of the natural watercourse and onto the roadway. A diverted stream is one of the most dangerous and erosion-inducing situations that can occur on a road. The diverted streamflow can wreak havoc on the road surface for hundreds of feet and can cause serious damage to the road and features below the road where it finally exits the road surface. This is why it is important to assess a road network for all potential stream diversions and employ simple BMPs to prevent stream diversions from occurring. The goal is to have a road design that would keep the stream within its natural watercourse in the event that the drainage structure at the road was overwhelmed. If the water flows over the road surface and directly back into its natural watercourse, then only the road prism within the crossing is at risk. This is far preferable to the potential of losing much more road and causing significant environmental and structural damage.
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When assessing the stream crossings on a road network for diversion potential, look closely at each individual crossing. This is not an assessment that can be done by looking at a map or satellite imagery. When looking at an individual stream crossing, picture what would happen if the stream culvert or other drainage structure were to plug or become overwhelmed during a storm event. If the streamflow is slowed down or stopped at the culvert inlet and rose to the level of the road surface, would the streamflow simply cross the road, exit down the fill slope, and enter back into its natural watercourse? Or would it enter the road bed and divert down the road? Look for the low spot on the road surface and see if it would serve as a diversion point. Sometimes a clinometer or other gradient measuring tool can be helpful in deducing the direction of the road slope. If the roadway in both directions drains down toward the stream crossing, there is no diversion potential. The water would not escape its watercourse and would stay within its channel. If one of the road directions slopes downward away from the stream crossing, then there is diversion potential. Eliminating diversion potential is not as difficult as it may seem. The easiest way to accomplish this is to create a dip in the road on the downslope side of the stream crossing. This is a similar feature as a rolling dip but we refer to it as a critical dip due to its critical need. The critical dip is designed to prevent water that has entered the roadway from diverting down the road. The critical dip should be deep and wide enough to capture all potential streamflow that could enter the roadway and designed to carry that flow across the road and route it directly back into the natural watercourse. Riprap can be placed at the critical dip outfall to protect the road from incision by the stream. The critical dip is an inexpensive and effective way to protect a road and prevent sedimentation of the local stream network. In the case where the steepness of a road or pavement of a road surface makes it dangerous or too expensive to install a critical dip to prevent diversion, a critical culvert may be installed A critical culvert is usually at least 18 to 24 inches in diameter and is placed in the road fill higher than the existing primary culvert and to the side where the streamflow would likely divert. This pipe is designed to capture flow that is building on the upstream side of the road due to the plugging of the primary culvert and usher it through the road prism and back into its natural watercourse. These pipes are generally not considered a failsafe, but can ease the pressure of rising water above the road and decrease the likelihood of the water overtopping the road until the storm abates.
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Waterbars Waterbars are most commonly built on inactive roads or avenues to divert flowing water from the road surface. They are often used where more expensive techniques, such as rolling dips, are not feasible. As improperly constructed waterbars can do more damage than good, following good planning and installation instructions are key to the effectiveness of this simple BMP. One key to successful sediment control is to deal with water in small amounts. Waterbar spacing, which decreases with increasing slope, is important to consider when planning waterbar use. The distance between bars breaks up the flow into manageable runs. It is important to remember, however, that waterbars need continual maintenance to function properly. Refer to Appendix 3: Road Best Management Practices for more information regarding installation and maintenance of the erosion control methods discussed here.
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Chapter 4: Managing Stormwater Runoff Stormwater runoff can be described as water that flows overland as surface water which has not been absorbed into groundwater nor has evaporated. It occurs when too much rain falls during a storm to be absorbed by the soil through percolation. How well the ground absorbs runoff depends on the amount of precipitation, type of soil/permeability, ground slope, and vegetation. Changes to the ground and area drainage patterns caused by farming practices can effect soil percolation and storm runoff.
Runoff Management ENVIRONMENTAL CONCERNS OF RUNOFF Stormwater runoff is a leading contributor to pollution Movement of pollutants downstream. in waterways. When managing farmland, care should be Disruption/destruction of natural ecosystems. taken to reduce the creation, concentration, and Damage to aquatic ecosystems. contamination of stormwater runoff. Stormwater runoff leaving your site should be clean. Impacts to water chemistry and quality. Decreased dry season flows. In a healthy ecosystem, soils allow infiltration and percolation which will absorb large amounts of Flooding. precipitation. When soils become saturated, sheet flow Erosion by rilling, gullying. will then carry stormwater runoff through established Sediment deposition. drainage channels. However, in an agricultural setting Changes to biodiversity. with altered drainage patterns, this runoff must be managed. Proven strategies for effectively dealing with Elevated flows leading to bank erosion. stormwater include: Lowered groundwater levels. Stormwater dispersion and infiltration. Stormwater retention and infiltration/storage. Stormwater redirection.
Stormwater Dispersion and Infiltration Keeping stormwater dispersed is the easiest and most cost-effective method of preventing impacts from runoff. This approach essentially mimics natural conditions by dispersing runoff over an area to promote infiltration while preventing concentration. Infiltration can be accomplished by incorporating vegetated swales and fiber rolls which assist in directing runoff and promoting infiltration of sheet flow. When conditions allow, this method is especially effective at reducing flow velocity and volume. Filtering of runoff through soil and vegetation removes sediments and other pollutants from reaching watercourses. Swales, vegetated waterways, v-ditches and fiber rolls are typical BMPs used in this approach.
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Stormwater Retention and Infiltration or Storage Excess stormwater can also be channeled via swales or v-ditches to a surface retention basin where the water can be filtered by rock, gravel, and/or plants prior to percolation to groundwater. Generally, the infiltration area is a location that has been specifically identified to allow water to percolate into the soil over time. This approach is highly effective in recharging groundwater but requires substantial space and infrastructure development. Retention basins and swales or bioswales are key components of this approach. Retention basins may also be lined to prevent percolation to unstable areas and instead may outfall to appropriate areas. An important point of note when designing this practice: adequate overflow must be correctly sized and directed to convey concentrated runoff. Properly designed, overflow should only rarely occur during large storm events when saturated conditions exist. Stormwater Redirection Redirection of stormwater is usually accomplished via a system of pipes with inlets and/or v-ditches. The stormwater is collected via pipes and routed to an outfall with an energy dissipation system. Very careful attention to the outfall area is critical. The outfall water should never be directed into the bed or banks of a waterway or onto neighboring properties but should be released outside of appropriate riparian setbacks and in a location and design that minimizes erosion. Subdrains and piped systems that concentrate and redirect flows can have serious impacts on the hydrology of the area and an engineered design is strongly recommended. Permits may also be required.
Best Management Practices for Stormwater The management of stormwater is site-specific depending on soils, slopes, precipitation, and agricultural needs. Each site should be evaluated with those elements in mind and should include professional engineering especially on slopes or when conditions warrant. The following BMPs reflect the most commonly used solutions for stormwater management. Vegetated Ditches and Swales Vegetated swales are open, shallow channels that collect and slowly convey runoff to downstream discharge points. They trap pollutants, promote infiltration, and reduce the flow velocity of runoff. A thick vegetative cover is needed for swales to function properly. Usually, swales require normal landscape maintenance such as irrigation and mowing to maintain efficiency but fertilizers and pesticides should be minimized or eliminated. These structures must be designed to handle peak flows of stormwater. Swales and ditches should follow the topography of the land, be properly spaced, be sized for stormwater runoff volume and for swale storage volume. In conjunction with swales, fiber rolls or wattles are often used upslope to further slow runoff. It is important to have a rock armored outfall for energy dissipation at the end of the ditch/swale if the water is not going into another drainage structure.
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Retention Basins Stormwater can be retained for infiltration, an approach that is highly effective in recharging groundwater and controlling runoff. It can be less practical for agricultural operations as it requires substantial space and infrastructure development. When designing a retention basin, directing runoff through a grass buffer before entering the infiltration structure will assist in removing sediments prior to reaching the basin. The basin will serve as a settling pond for remaining sediments. An important component of this method is adequate overflow. Should the amount of stormwater exceed the available infiltration, the excess water must be conveyed away from the area without causing erosion. This conveyance of concentrated stormwater and its outfall must be properly sited to avoid any impacts downstream. It is recommended that a professional engineer design the retention basin and any conveyance structures. Diversion Ditches A diversion ditch is an engineered channel constructed across slope to intercept and re-route concentrated runoff away from areas that could otherwise be eroded. A diversion ditch can be earthen or rock-lined, and may be vegetated. The diversion is integrated into other natural or engineered drainage, at grade, and with proper energy dissipation. Streamflow conveyance capacity should be calculated to exceed estimated peak discharge following a 100-year, 24-hour storm event.
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Engineered Drainage Many existing agricultural operations have engineered subsurface drainage pipes used to collect surface runoff. Typically engineered by a professional, piped drainage systems convey excess subsurface water via the pipe network away from the vineyard to an appropriate outfall. Engineered drainage (subsurface) systems benefit water quality in two ways: it reduces surface runoff that would otherwise occur and it allows water to be diverted from areas where pollutants may be present. The use of cover crops, vegetated swales, or rocked v- ditches provides a filter for the sediment-laden runoff prior to entering the piped system. Stormwater runoff enters the pipe at a drop inlet. The drop inlets should be spaced such that runoff is captured before it concentrates on the surface and causes erosion. To further filter remaining sediments, all inlets should have a sediment collection collar. After collecting the runoff, the pipe will discharge the water at a surface outlet (outfall). All outfalls should have an appropriately sized energy dissipater. These may include rock riprap, t-spreaders, sediment basins, or a retention basin. Outlets should not be located in stream channels or along the top of a streambank. Maintenance of these structures is critical to their effectiveness. Sediment collars should be monitored after storm events and cleaned as necessary, energy dissipaters re-rocked as needed, cover crops reseeded, and swales and ditches cleaned and properly vegetated or rocked. Piped drainage system design must consider soils, slope, precipitation, and agricultural operations as well as watershed processes. As with all erosion control measures, these systems require regular maintenance to function properly. A professional engineer must be retained for these systems.
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Chapter 5: Managing Gullies and Shallow Landslides Gully Formation A gully is an erosional feature consisting of a deep channel cut into the surface of a soil covered hillside. Gullies are formed by an increase in surface runoff combined with manmade and physical factors influencing the erosional process. Once begun, gully formation will continue unless measures are taken to stabilize the disturbance. FACTORS AFFECTING GULLY FORMATION The concentrated flow of surface water causing gully formation can be the result of a natural process, but is Improper land use. more commonly the result of human modifications to the Forest and grass fires. ground surface or drainage conditions upslope of the gully. Mining. Gullies can be identified by their v-shaped, u-shaped, or Road construction. trapezoidal channels oriented in the downhill direction. Livestock and vehicle trails. These formations are the result of the runoff Precipitation. characteristics of the watershed, drainage area, soil characteristics, alignment, size, and shape of the gully, and Topography. gradient of the gully channel. Soil properties. Gullies cannot be eliminated by tilling. Control measures Vegetative cover. must be determined by the root causes and the Destructive logging. development stage of the gully.
Shallow Landslides A landslide is an abrupt downslope movement of a soil or rock mass. Where a landslide is less than three feet thick, it is considered shallow. Shallow landslides are often caused by weak or loose soils sitting on slopes steeper than 20%. These failures occur when surface soils become saturated, weakening them and making them heavier. Shallow landslides are often the result of ground or drainage disturbance resulting from agricultural development of steep slopes. Unless steps are taken to stabilize the slope movement, landslides can continue to grow, resulting in greater ground and drainage disturbance. Shallow landslides can be identified by a loose pile of soil (slide debris) downslope of a freshly exposed ground surface (scarp) lacking in established vegetation. The scarp is often semi-circular in shape with the arc pointing uphill, and the slide debris is often lumpy, irregularly shaped, and cracked.
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How to Prevent Gullies and Shallow Landslides Preventing land degradation from gullies and shallow landslides begins with identifying areas that already display the characteristic features described above. Observe soil conditions on slopes, especially after rain events, to check for signs of the development of gullies or shallow landslides. Areas already experiencing these conditions are likely to continue expanding until repaired. Gullies and shallow landslides can be prevented from forming by limiting the conditions which cause them. Gullies can be prevented by: HUMAN CAUSES OF LANDSLIDES Avoiding flow concentration. Slowing flow velocities. Excavation of slope or its toe. Construction of a non-erodible drainage system, Loading of slope or its crest. such as a French drain, piped storm drain, or Drawdown of reservoirs. armored channel. Deforestation. Shallow landslides can be prevented by: Irrigation. Stabilizing the area with large vegetation. Drainage alterations. Compacting soils. Directing surface water away from the slide. Draining groundwater and/or surface water by installing a drainage system. Avoiding disturbance of erodible soils and slopes steeper than 20%. In cases where farming will be performed on a slope greater than 20%, or where landslides greater than three feet in thickness develop or are encountered, repair measures should be designed by an engineering geologist, geotechnical engineer, or a civil engineer after a professional geotechnical assessment.
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How to Repair Gullies and Shallow Landslides Gullies and landslides should be repaired only after the source of the problem has been identified and treated. The services of a professional engineer are strongly recommended in order to ensure a successful, permanent solution. There are varying levels of repair cost and effectiveness, so selecting the appropriate repair method depends primarily on the intended land use, and the potentially negative consequences of the gully or landslide formation and growth. Gully and landslide control is one of the most important restorations within a watershed and timing is an essential element. The field work for all structural and vegetative control measures selected should be completed during the dry season. This allows structural work to be completed and installed vegetation time to root prior to damaging rains. Minimal disturbance to the existing landscape should be a primary goal for any restoration technique. Gullies Gullies are typically a symptom of another problem such as a poorly placed culvert or other factor that has concentrated and increased water flows on the land. Once the source of the runoff that caused the gully is identified and treated, the task of repairing the gully remains. If the gully formed in a previously existing stream channel or swale where water naturally flows, your task is to stabilize the headcut and banks of the gully. If the gully formed where water would not naturally flow and you have redirected the runoff to a more appropriate location, the most complete repair would be to restore the natural landform, complete with reseeding and mulching. Gullies can be repaired with several techniques. Bioengineered methods, engineered solutions, or a combination of both have proven effective. Gullies can be prevented from recurring by identifying and correcting the causes of upslope drainage concentration. This is often as simple as collecting surface runoff in a ditch and directing it into an appropriate drainage, in a controlled fashion. Gullies in non-agricultural areas can also be prevented from further growth by armoring the channel with rock slope protection or employing bioengineered structures to trap sediments and vegetate eroded soils. Planting site-appropriate vegetation will provide anchoring root systems to protect the exposed soils. In agricultural areas, the upper surface of the compacted soil can be loosened and amended for planting and root growth, following the recommendations of a geotechnical engineer.
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Landslides The hazard from landslides can be reduced by avoiding construction on steep slopes and existing landslides, or by stabilizing the slopes. Stability increases when groundwater is prevented from rising in the landslide mass by: Covering the landslide with an impermeable membrane. Directing surface water away from the landslide. Draining groundwater away from the landslide. Minimizing surface irrigation. Slope stability is also increased when a retaining structure and/or weight of a soil/rock berm are placed at the toe of the landslide or when mass is removed from the top of the slope. Shallow landslides can be repaired by reconstructing the slope following engineered designs. With geotechnical analysis and oversight, the upper surface of the compacted soil can then be loosened and amended for agricultural use. Shallow landslides in non-agricultural areas can also be repaired by either engineered designs, bioengineered solutions, or a combination of both. It is strongly recommended that a professional geologist or geotechnical engineer design and manage landslide repairs. Due to the complex nature of landslide repair, this Guide does not present BMPs appropriate for landslide repair.
Bioengineering for Gullies Soil bioengineering techniques such as brush layering, willow walls, or fabric reinforced earth fill can be used to prevent sediment transport and reinforce fresh or repaired slopes. These techniques can be used in combination with hardscape repair techniques, or in place of them as a less invasive approach on slopes. Brush layering is a technique used to reinforce soil slopes and trap sediment by installing dense layers of live brush under compacted soil in flat benches cut into the hillside. Fabric reinforced earth fill is another technique used to integrate live willow brush into the reconstruction of a compacted soil slope. This technique involves blanketing the unstable soil with a layer of filter fabric keyed in at the top of the reconstructed slope. The fabric is covered with a newly constructed slope of compacted soil containing layers of live willow brush. The toe of the fill slope is supported and drained by a layer of rock. For more information on installation of bioengineered solutions, see Appendix 5: Gullies. If the gullies or shallow landslides cannot be repaired with these methods or the consequences can result in damage to property or human health, you should consult with a geotechnical engineer and/or engineering professional to develop a repair design.
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Chapter 6: Pollutant Control – Managing Pesticides Maintaining and improving water quality on agricultural operations is important to the current and long-term sustainability of these ecosystems and an essential component of whole farm planning. Pesticides pose a great risk to soil health and both surface and groundwater quality as a pollutant when they are not used appropriately. This chapter examines BMPs that may be implemented to keep pesticides from polluting surface and groundwater resources. A fundamental prerequisite for improving and maintaining water quality in vineyards and orchards is the implementation of an Integrated Pest Management (IPM) program. IPM is an ecosystem-based strategy that focuses on long-term prevention of pests and their damage through a combination of techniques such as biological control, habitat manipulation, modifying cultural practices, using resistant varieties, and a suite of other techniques including the judicious application of pesticides when necessary.
Basic Integrated Pest Management Principles
THERE IS NO SILVER BULLET
•Over reliance on any single control measure can have undesirable effects, including resistance, resurgence, and replacement.
TOLERATE, DON'T ERADICATE
•Most crops tolerate low pest infestation levels. •IPM seeks to reduce pest populations below levels that are economically damaging rather than to totally eliminate infestations.
TREAT THE CAUSES, NOT THE SYMPTOMS
•IPM requires a detailed understanding of pest biology and ecology so crops can selectively be manipulated to the pest’s disadvantage.
IF YOU KILL THE NATURAL ENEMIES, YOU INHERIT THEIR JOB
•Naturally occurring predators, parasites, pathogens, antagonists, and competitors help keep many pests in check. •IPM strives to enhance impact of beneficial and other natural controls by conserving or augmenting those agents.
PESTICIDES ARE NOT A SUBSTITUTE FOR GOOD FARMING
•A vigorously growing plant can better defend itself against pests than a stressed plant. •IPM takes maximum advantage of farming practices that promote plant health and allow crops to escape or tolerate pest injury.
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Integrated Pest Management Considerations Plants, like animals, have evolved complex defenses against enemies. These defenses can include camouflage, armored outer skins, thorns or spikes or chemical deterrents, or symbiotic relationships that inhibit attack. Such abilities, as with any immune system, are strongest when the plant is healthy. That health is optimal when the needs of the plant are fully met which requires a healthy soil ecosystem with a high carbon content and a diverse and large population of microbes. The first order of business is to practice regenerative agriculture and tend to soil ecosystem restoration and resiliency. Regenerative management addresses overall balance, and dealing with pests is no different. Trellis type, plant material, canopy management, floor management, fertilization, and irrigation are all factors that must be taken into account to prevent, mitigate, or manage pest, weed, and disease outbreaks. IPM management practices include:
Scouting blocks regularly. Maintaining detailed records. Using good sanitation practices. Removing alternate host plants. Controlling dust. Using plant varieties and rootstock resistant to phylloxera and nematodes when planting and replanting. Basing application data decisions on scouting data, pest thresholds and/or risk assessment models. Applying pesticides at lowest effective labeled rate. Best Management Practices for Pesticides The BMPs listed below can help determine the safest placement of storage and mixing facilities to prevent contamination of surface and groundwater or exposure to wildlife:
Establish an IPM program to reduce pesticide use and the potential contamination of surface and groundwater with pesticides. Introduce populations of beneficial insects when appropriate to eliminate the need for applying pesticides. Where feasible and appropriate, use non-chemical control tactics to reduce overall pesticide use. When chemical pest control is necessary, select reduced risk pesticide products to prevent contamination of surface and groundwater with toxic chemicals. Use organic materials when and where conditions allow and are economically feasible. Base application decisions on environmental conditions (wind, rain, temperature, etc.), scouting data, pest thresholds, and/or risk assessment models.
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Operators may use pest traps or traps monitored by the Sonoma County Department of Agriculture/Weights & Measures to determine if there is a need to apply pesticides, which will eliminate unnecessary pesticide applications. Select pesticides with lower risk of runoff or leaching based on pesticide chemistry and site conditions to help prevent any materials from entering adjacent watercourses through runoff and/or soil movement. . The potential for pesticide products to move offsite include soil properties, climate, management practices, physical and chemical properties of the pesticide’s active ingredients, and any adjuvants found in or added to the tank mix. . The likelihood that a pesticide will move in surface water runoff depends on the properties of the active ingredient, such as its soil half-life, adsorption coefficient, and aqueous solubility. . Studies have been completed that evaluate the potential of a pesticide product to move in dissolved form (solution runoff) or with soil (adsorption runoff). University of California Cooperative Extension, Division of Agriculture and Natural Resources categorizes insecticides, fungicides, miticides, and herbicides according to their overall runoff risk and presents these findings in convenient tables. These tables can serve as a valuable resource for selecting pesticide products with a moderate to low risk of runoff. This publication, number 8161, can be found at https://anrcatalog.ucanr.edu/pdf/8161.pdf. Locate pesticide storage, mixing, and loading facilities outside of the flood plain or areas prone to flooding 50 feet from surface waters, and in a manner consistent with labeling and regulations. Wellhead protection prohibits the following within 100 feet of an unprotected (non-bermed) well: . Mixing, loading and storage of pesticides. . Rinsing of spray equipment or pesticide containers. . Maintenance of spray equipment which could result in spillage and contamination. . Application of listed pre-emergent pesticides. Employ procedures to avoid pesticide spills and leakage during all phases of transport, storage, and application. Incorporate secondary containment and impermeable surfaces within site. Provide regular and comprehensive training sessions for applicators and other handlers of pesticide products to ensure they understand and comply with laws, regulations, and procedures meant to eliminate contamination of surface and groundwater with pesticides. Ensure that runoff and sediment containing pesticide chemical residues does not move offsite in water or wind. Use vegetative buffers and/or grassy filter strips downslope of irrigated lands to stabilize soil in the area and help filter pesticide-containing sediment out of stormwater. Use grassed waterways, lined channels, and/or diversions in ditches and channel banks to stabilize soil and prevent sediment particles, which may contain pesticide products, from eroding and moving offsite with drain and stormwater.
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At least once a year, check and calibrate application equipment and/or injectors. This will identify faulty equipment and eliminate the possibility of excessive chemical application, over spray, and/or drift that could adversely affect adjacent waterways. Incorporate a backflow prevention system or air gap so that pesticides cannot enter the water source when filling sprayers. Consult with a University of California Cooperative Extension Farm Advisor or licensed Pest Control Adviser to identify any unknown causes of crop damage in order to determine the correct method of pest control. Agricultural regulatory agencies throughout the state of California are responsible for enforcing laws and regulations pertaining to pesticide use and water quality. These regulations include:
Certain activities are prohibited within 100 feet of a well unless wellhead is protected as required. All pesticide application equipment and service rigs that draw water from an outside source to have appropriate backflow prevention. Groundwater protection areas are identified as an area being vulnerable to the movement of pesticides to groundwater. Certain pre-emergent herbicides listed on the Groundwater Protection List have additional requirements when used in these areas. Restrictions placed on the application of dormant season insecticides. Proper storage of pesticides in a dry, locked enclosure, with posting visible from 25 feet away, located outside of flood plain and riparian areas, away from wellheads, and secured from wildlife. A secondary containment system is recommended in the event of spills. Prepare and keep a Spill Prevention, Control, and Countermeasures Plan onsite. Maintain a supply of appropriate cleanup materials within the storage area.
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Chapter 7: Pollutant Control – Managing Nutrients Nutrients are essential to all plant and animal life. Agricultural crops generally obtain their nutrients through roots or leaves, from the soil, water, and atmosphere. Management of nutrients serves the following functions: It supplies essential nutrients to soils and plants for optimum production. It provides for efficient and effective use of scarce nutrients to minimize waste. It minimizes environmental degradation caused by runoff. It helps maintain or improve physical, chemical, and biological condition of the soil. Proper nutrient management economizes the natural EXCESS NUTRIENT IMPACTS ON ENVIRONMENT process of nutrient cycling to optimize crop growth and minimize environmental impacts. Excess movement of Water quality concerns. nutrients, primarily from runoff and erosion, can Agronomic concerns. contribute to degradation of water quality and create an Air quality concerns. imbalance in the ecosystem by destroying soil carbon and depleting soil organic matter. Inefficient use of resources. The objective of nutrient management is to supply adequate chemical elements to the plants without AGRONOMIC ASSESSMENT TOOLS creating environmental impacts. Some management Soil tests. considerations include improving soil surface structure Plant tests. and promoting greater infiltration to reduce runoff and the loss of soluble nutrients, proper management of Analysis of organic nutrient sources. irrigation, and knowledge of soil types and their leaching Irrigation water analysis. potential and transport. Development of a nutrient budget can be accomplished through the use of readily available assessment tools. In addition, environmental risk assessment tools can provide information on the potential environmental risk associated with nutrient applications and may be used to identify sensitive areas in which nutrient management is critical to protect sensitive resources. Development of a nutrient management plan should include decisions on placement, rate, timing, form, and method of nutrient application within environmental considerations. The effective implementation of the plan requires frequent review of the plan, periodic monitoring of progress, and continual maintenance. A robust nutrient management plan, along with recommended BMPs, will assist growers in meeting Water Board Waiver of Waste Discharge Requirements (WDRs).
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As developed for Region 2, the Water Board WDRs require that BMPs address the following with regard to nutrient management: Employ methodology to determine nutrient needs of the vine and apply only the amount needed. Establish optimal delivery of nutrients to maximize vine uptake and use. Storage and preparation of fertilizers. The use of backflow prevention devices when drawing water from an outside source. Establishing vegetative barriers to filter runoff. Determining Nutrient Needs of the Plant Soil analysis and site assessment will assist in identifying any chemical imbalances or deficiencies in mineral nutrients. Soil samples are typically collected in winter with a small hand-held core over representative areas within the vineyard. Results will drive addition of necessary amendments.
NUTRIENT MANAGEMENT PLAN COMPONENTS IMPORTANCE OF FLOOR MANAGEMENT
Site maps, including soil map. Small root zone to exploit.
Location of nutrient application restrictions Manage soil to provide good root and soil within or near sensitive areas or resources. environment. Results of soil, plant, water, and organic Not just nutrient management, but soil nutrient source analysis. management. Current or planned plant production system Feed the soil to feed the crop. or rotation. Expected yields.
Quantification of all important nutrient sources. FLOOR MANAGEMENT TECHNIQUES Nutrient budget for the complete plant production system. Minimize cultivation – maintain undisturbed root zone. Recommended rate, timing, and methods of application. Divide fertilizer applications to optimize nutrient use. Operation and maintenance of nutrient management plan. Ensure good drainage.
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Fertigation Fertigation is widely used in vineyards and orchards to deliver nutrients efficiently and economically through the irrigation system. When fertigating, the following BMPs should be followed:
Analyze irrigation water for chemistry and existing levels of nutrients. SOIL NUTRIENT MANAGEMENT Assure that fertilizer is kept in the root zone by Best nutrient management practices combine using a soil moisture meter to verify the depth of compost, composted manure, and/or cover application. crops with specific fertilizer applications. Ensure fertilizers are compatible with irrigation Increased organic matter keeps nutrients in water quality and soil chemistry. the root zone and makes fertilizer applications more effective. Use proper injection rates. Legume cover crops can contribute nitrogen. Flush the system in a safe area with clean water following fertigation to avoid leaching. Storing and Mixing Fertilizers
Locate storage facility outside flood plain, outside of riparian areas, away from surface waters and wellheads, and secured from wildlife. Fertilizers should be stored in a dry, locked enclosure and posted as fertilizer storage for fire personnel. Store large drums or bags up off the floor using pallets or similar means. Storage area should have an impermeable floor with secondary containment. Store fertilizers in original containers with labels. Do not use any food or beverage containers to store fertilizers. Mix fertilizers on impermeable surface with secondary containment. Prepare and post a Spill Prevention, Control, and Countermeasures Plan. Keep spill kit in immediate vicinity (absorbent materials, shovel, dustpan, broom, buckets, etc.).
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Use of Backflow Prevention Devices All application equipment used to apply pesticides or fertilizers that draw water from an outside source shall be equipped with an air gap separation, reduced pressure principal backflow prevention device, or a double-check valve assembly.
Establishing Vegetative Barriers to Filter Runoff Vegetative barriers are recommended between the vineyard and waterways or any areas exhibiting erosion. Adequate filter strips or hedgerows consisting of dense vegetation should be established to intercept surface water and filter transported sediment. The recommended width of filter strips is 10 feet to 35 feet, depending on the slope of the draining area. For more information, please visit http://ucfoodsafety.ucdavis.edu/files/26499.pdf.
Vegetation equals erosion control.
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Chapter 8: Winterization and Sustainable Maintenance Winterization Winterization of agricultural areas is critical to the prevention of erosion. Some steps to take to prepare for the wet season include:
Analysis of soil amendments and resulting adjustments needed to improve the health of the soil and mineral balance. Addition of compost and seeding of cover crops in between rows. Composted biochar may be added to provide beneficial carbon and soil structure. Distribution of straw, placement of wattles, and creation of v-ditches to reduce the impacts of stormwater runoff. Collecting displaced soil that has moved and replacing it where needed. Inspection and repair of roads. Clearing culverts, inlets, outlets, and trash racks. Replacing rock at inlets, outlets, and energy dissipaters. Seeding and mulching of avenues and any bare soils. Retain onsite extra erosion control materials such as straw wattles, straw bales, gravel, or geotextile fabric and train vineyard crews on their proper installation. During erosion control failures, train crew on proper repair techniques. Riparian Areas and Streams
Riparian areas should never be used as a staging area where pollutants can be delivered to watercourses. All equipment, trellising, t-posts, fencing or other vineyard materials should be staged at least 50 feet from riparian areas. Inspect streambanks for erosion. If erosion or bank failure threatens, contact your local RCD for assistance. Repair stream crossings. Monitor for sediment delivery.
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Monitoring and Maintaining Best Management Practices It is important to observe the effectiveness of drainage BMPs. Walk the site during and after rain events, observing where runoff is occurring and concentrating, where erosion is occurring, and where sediment is being picked up. Immediately repair any occurring erosion and note on your Erosion Control Plan (ECP) what adaptive measures you are taking. Perform routine BMP monitoring/maintenance as needed:
Remove accumulated debris, litter, and sediment. Stabilize/replace any inlet/outlet structures as needed. Replace non-native vegetation with native species. Repair/replace damaged wattles, bales, or silt fences. Reseed and mulch bare surface areas; irrigate to achieve minimum height standards prior to winter. Inspect and maintain waterbars, water deflectors, and channel drains. Inspect roads drainage areas for signs of erosion. Monitor infiltration capacity of swales and v-ditches. Allowing contaminated storm runoff to leave an operation or to enter streams or wetlands on the operation site may result in serious legal consequences. If despite using these BMPs, cloudy or dirty water is seen leaving the operation during storm events, a design professional experienced with developing ECPs should be consulted for assistance.
Vineyard Waste Dead brush from pruning material and vegetation management projects need to be reduced. Burning and chipping are common methods of reduction, but can cause air quality and fire hazard issues. The Biochar Alternative Biochar is wood waste that is pyrolyzed under low oxygen, high heat conditions. This creates a product that has a tremendous amount of surface area, and this composition is excellent at holding nutrients, moisture, and beneficial bacteria and mycorrhizae. Producing biochar onsite in vineyards may be feasible during removal and replant by burning piles of debris through pyrolysis. Conservation burning (pyrolysis) burns from the top down, with virtually no smoke and leaves a carbon-rich residue which, when composted, may be applied to the vineyard. Conservation burning minimizes air pollution emissions by 85% to 95% while also capturing and conserving about 25% of the carbon in the biomass. The use of biochar has the potential to provide the same or better vine growth with less fertilizer and nutrient inputs, and with less irrigation water. It can also provide long-term carbon benefits.
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Glossary A-Frame Level: Low-tech device used to find contour lines. A-frame levels are economical, simple to construct, do not require water, and can be used by one person. There are numerous videos online for constructing and using an a-frame level. Agricultural Drainage: The natural or artificial removal of stormwater from cropland. Drainage includes the construction, maintenance, repair, replacement, and modification of drainage facilities and other methods of drainage to prepare new land for crop production or to maintain land in crop production. Agricultural Grading: An excavation, fill, or combination thereof to prepare new land for crop production or to maintain land in crop production. Best Management Practice (BMP): Methods or measures designed and selected to effectively control the discharge of pollutants from point and nonpoint source discharges. Bioengineering: Several methods of soil stabilization emphasizing the incorporation of biological materials such as plants, plant parts (e.g. root wads), or a combination of vegetation and inert materials (e.g. brush mats, wattles, fascines, or branch packing/layering). Bunyip Water Level: Low-tech device used to find contour lines. Bunyip water levels are economical and simple to construct. Drainage Facility: A manmade feature intended to collect, direct, or convey stormwater. Drainage facilities include swales, ditches, pipes, culverts, drainage inlets (catch basins), detention/retention basins, and reservoirs. Erosion: The detachment and movement of soil and rock fragments by water or under the force of gravity, which result in the wearing away of the land. When water is the eroding agent, erosional processes include sheet and rill erosion, gully erosion, and channel erosion. Erosion Control Best Management Practices: Vegetation, such as grasses, forbs and wildflowers, and other materials, such as straw, fiber, stabilizing emulsion, protective blankets, etc., placed to stabilize areas of disturbed soils, reduce loss of soil due to the action of water or wind, and prevent water pollution. Fertigation: The injection of fertilizers, soil amendments, and other water soluble products into an irrigation system for delivery to crops. Highly Erodible Soils: For Sonoma County, soils in the Diablo, Dibble, Goldridge, Laughlin, Los Osos, Steinbeck, and Suther soil series or complex as mapped by the U.S. Department of Agriculture. Hillslope Vineyard: An area where grapes are planted on an average slope that is greater than 5%. Hydrologic Connectivity: Having a continuous surface flow path (road ditches, road surfaces, gullies, or other drainage structures or disturbed surfaces) to a natural stream channel during a storm runoff event. Hydromodification: Altering the drainage patterns (away from their natural state) of a site and the flows, beds or banks of rivers, streams, or creeks, including ephemeral washes, which results in hydrogeomorphic or habitat changes. Incision: The progressive lowering of streambed elevation over time, as a result of net erosion.
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Infiltration: The downward movement of water into the soil surface. Infiltration Capacity: The maximum rate at which the soil can absorb water. Integrated Pest Management (IPM): An ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and non-target organisms, and the environment. Invasive Plant Species: Invasive, non-native plants that are not native to, yet can spread to wildland ecosystems and that also displace native species, hybridize with native species, alter biological communities or alter ecosystem processes. Land Disturbance: Any activity or use that changes the physical conditions of land form, vegetation and hydrology, creates bare soil, or otherwise may cause erosion or sedimentation. Land disturbance includes land clearing, soil preparation, grading, vegetation removal, roads, materials staging, or other similar activities. Landowner: An owner or proprietor of land. Nonpoint Source: The Clean Water Act focuses on two possible sources of pollution: point and nonpoint. Point sources refer to discrete discharges, such as from a pipe. Nonpoint refers to everything else, including agricultural runoff. Orchard Properties: The entire parcel or contiguous parcels under the same ownership, where orchard trees are planted on part of the property. Percolation: The flow of water through the soil matrix, and through porous or fractured rock. RCD: Resource Conservation District. Riparian Corridor: Located along the edge of a channel, generally on the floodplain. Characterized by access to and influence of the channel, but not in it. A riparian zone or riparian area is the interface between land and a river system. Riparian habitat is composed of trees and other vegetation and physical features normally found on the streambanks and flood plains associated with streams, lakes, or other bodies of water. Riparian Vegetation: Plant communities contiguous to and affected by surface and subsurface hydrologic features of waterbodies (rivers, streams, lakes, or wetlands) that have one or both of the following characteristics: distinctly different vegetative species than adjacent areas, and species similar to adjacent areas but exhibiting more vigorous or robust growth forms. Sediment: Solid particulate matter, both mineral and organic, that is in suspension, is being transported, or has been moved from its site of origin by air, water, gravity, or ice and has come to rest on the earth’s surface either above or below sea level. Sediment Control Best Management Practices: Practices that trap soil particles after they have been eroded by rain, flowing water, or wind. They include those practices that intercept and slow or detain the flow of stormwater to allow sediment to settle and be trapped.
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Slope: An inclined surface, the inclination of which is expressed as a ratio of vertical distance (rise) to horizontal distance (run) (e.g. 2:1) or as a percentage (e.g. 50%). Calculated as slope% = rise/run. Stormwater: Runoff generated by rainfall. Stream: The term “stream” is commonly understood as a watercourse having a source and terminus, banks, and bed/channel, through which waters flow, at least periodically and supports fish or other aquatic life. This includes watercourses having a surface or subsurface flow that supports or has supported riparian vegetation. Vineyard Properties: The entire parcel or contiguous parcels under the same ownership, where grapevines are planted on part of the property.
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Additional Resources County Agencies Sonoma County Department of Agriculture/Weights & Measures 133 Aviation Boulevard, Suite 110, Santa Rosa, CA 95403 Phone: (707) 565-2371 Website: www.sonomacounty.ca.gov/AWM University of California Cooperative Extension – Sonoma County 133 Aviation Boulevard, Suite 109, Santa Rosa, CA 95403 Phone: (707) 565-2621 Website: http://cesonoma.ucanr.edu Sonoma County Farm Bureau 3589 Westwind Boulevard, Santa Rosa, CA 95403 Phone: (707) 544-5575 Website: www.sonomafb.org
Resource Conservation Districts Sonoma RCD 1221 Farmers Lane, Suite F, Santa Rosa, CA 95405 Phone: (707) 569-1448 Website: www.sonomarcd.org Goldridge RCD 2776 Sullivan Road, Sebastopol, CA 95472 Phone: (707) 823-5244 Website: www.goldridgercd.org Napa County RCD 1303 Jefferson Street, Suite 500B, Napa, CA 94559 Phone: (707) 252-4189 Website: www.naparcd.org Marin RCD PO Box 1146, Point Reyes Station, CA 94956 Phone: (415) 663-1170 Website: www.marinrcd.org
Natural Resource Conservation Service NRCS Santa Rosa Service Center 2150 W College Avenue, Santa Rosa, CA 95401 Phone: (707) 569-1448 Website: www.nrcs.usda.gov
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Regional Water Boards Region 1: North Coast Regional Water Quality Control Board 5550 Skylane Boulevard, Suite A, Santa Rosa, CA 95403 Phone: (707) 576-2220 Website: www.waterboards.ca.gov/northcoast/ Region 2: San Francisco Bay Regional Water Quality Control Board 1515 Clay Street, Suite 1400, Oakland, CA 94612 Phone: (510) 622-2300 Website: www.waterboards.ca.gov/sanfranciscobay/
Water Quality Agriculture Water Quality Alliance (AWQA) Website: www.awqa.org Sediment and Erosions Control Plans (SECP) – Grower Self-Certification Training Website: https://esjcoalition.org/secpSection1.pdf
Growers Associations Sonoma County Winegrape Commission 400 Aviation Boulevard, Suite 500, Santa Rosa, CA 95403 Phone: (707) 522-5868 Website: www.sonomawinegrape.org California Sustainable Winegrowing Alliance 425 Market Street, Suite 1000, San Francisco, CA 94105 Phone: (415) 356-7548 Website: www.sustainablewinegrowing.org Russian River Valley Winegrowers 3210 Woolsey Road, Windsor, CA 95492 Phone: (707) 521-2534 Website: www.rrvw.org Alexander Valley Winegrowers PO Box 248, Healdsburg, CA 95448 Phone: (707) 431-2894 Website: https://alexandervalley.org Sonoma Valley Vintners and Growers Alliance 783 Broadway, Sonoma, CA 95476 Phone: (707) 935-0803 Website: www.sonomavalleywine.com
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Third-Party Systems Landsmart Contact your local Resource Conservation District Website: www.landsmart.org Fish Friendly Farming 550 Gateway Drive, Napa, CA 94558 Phone: (707) 253-1226
Biochar Sonoma Biochar Initiative PO Box 2041, Glen Ellen, CA 95442 Phone: (707) 291-3240 Website: www.sonomabiocharinitiative.org Sonoma Ecology Center 15000 Arnold Drive, Eldridge, CA 95431 Phone: (707) 996-0712 Website: www.sonomaecologycenter.org
Bioengineering Carmel River Watershed Stewardship Manual Website: https://www.rcdmonterey.org/images/docs/publications/carmel-watershed-conservation-manual.pdf Soil Bioengineering Techniques Website: https://conservation-corps.squarespace.com/s/chapter5.pdf Soil Bioengineering for Upland Slope Protection Website: https://directives.sc.egov.usda.gov/17555.wba
Soils Soil Stability Website: https://www.youtube.com/watch?v=9_ItEhCrLoQ Soil Health Principles – Ray Archuleta Website: https://vimeo.com/channels/raythesoilguy Soil Foodweb – Dr. Elaine Ingham Website: www.soilfoodweb.com North Coast Soil Health Hub – Soil Health Initiative Website: http://soilhub.org Guidelines for Managing Biological Fertility of Soil Website: www.soilhealth.com
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Erosion Control and Cover Crop Seed Le Ballister’s Seed and Fertilizer Website: http://leballisters.com Harmony Farm Supply and Nursery Website: www.harmonyfarm.com
Other Resources Western Sustainable Agriculture Research and Education Website: www.westernsare.org Regenerative Agriculture Website: www.regenerationinternational.org Rodale Institute Website: https://rodaleinstitute.org Savory Institute Website: www.savory.global Biodynamic Association Website: https://www.biodynamics.com Rudolf Steiner College Website: www.steinercollege.edu Permaculture Institute Website: https://permaculture.org Agricultural Composting and Water Quality Website: http://smallfarms.oregonstate.edu/agricultural-composting-and-water-quality Quivira Coalition Website: https://quiviracoalition.org Biosol (an organic fertilizer that can also double as a pest deterrent) Website: www.biosol.com Compost Use in Agriculture Website: www.calrecycle.ca.gov/organics/farming Finding Slope/Contour Lines A-Frame and Bunyip Levels Website: www.harvestingrainwater.com/wp-content/uploads/2006/05/Bunyip-water-levels-and-A-frame-levels- Appendix-2.pdfd Video tutorial to construct and use a bunyip Website: https://youtu.be/nAcT_1T25LM
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References Archuleta, Ray. Soil Health Principles. Accessed April 11, 2017. https://www.youtube.com/watch?v=9uMPuF5oCPA. Archuleta, Ray. Soil Stability. Accessed April 11, 2017. https://youtu.be/9_ItEhCrLoQ. Bernier, Paul. Bernier Vineyards. Personal interview. September 14, 2017. Brown, Lester R. Eco-Economy: Building an Economy for the Earth. Earth Policy Institute, 2001. Accessed July 11, 2017. www.earth-policy.org/books/eco/eech3_ss5. California Department of Transportation (DOT). Soil Stabilization Using Erosion Control Blankets. Construction Storm Water Pollution Prevention Bulletin. Vol. 3, No. 8. Accessed July 21, 2017. www.dot.ca.gov/hq/env/stormwater/publicat/const/Aug_1999.pdf. California Regional Water Quality Control Board San Francisco Bay Region (RWQCB). Draft Waste Discharge Requirements for Vineyard Properties Order No. R2-2016-00XX. 2016. California Sustainable Winegrowing Alliance and California Association of Winegrape Growers (CSWA). California Code of Sustainable Winegrowing Workbook. Third Edition. San Francisco, CA. 2012. Central Valley Water Quality Coalitions (CVWQC). Sediment & Erosion Control Plans (SECP): Grower Self- Certification Training. Accessed May 8, 2017. www.svwqc.org/wp-content/uploads/2017/02/Consolidated_SECP_Self_Certification_Curriculum_Binder.pdf. Christensen, Peter. Use of Tissue Analysis in Viticulture. Proceedings of Varietal Winegrape Production Short Course. University of California Davis Extension. March 2005. http://iv.ucdavis.edu/files/24406.pdf. Ecological Society of America (ESA). Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems. Issues in Ecology. Number 2. Spring 1997. Washington, DC. Accessed April 28, 2017. www.esa.org/esa/wp-content/uploads/2013/03/issue2.pdf. Environmental Protection Agency (EPA). National Management Measures to Control Nonpoint Source Pollution from Agriculture. Chapter 4C: Erosion and Sediment Control. Pp. 89-106. July 2003. Accessed May 18, 2017. https://www.epa.gov/nps/national-management-measures-control-nonpoint-source-pollution-agriculture. Eurostat – Statistics Explained. Agri-Environmental Indicator – Soil Erosion. May 2015. Accessed July 12, 2017. http://ec.europa.eu/eurostat/statistics-explained/index.php/Agri-environmental_indicator_-_soil_erosion. Forestry Department of the Food and Agriculture Organization of the United Nations (FAO). FAO Watershed Management Field Manual – Gully Control. 2006. Accessed June 15, 2017. www.fao.org/docrep/006/ad082e/AD082e00.htm. Goldmand, Steven J., et al. Erosion and Sediment Control Handbook. McGraw-Hill, Inc. United States. 1986.
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Groff, Steve. Presentation quote. No-Till Management of Cover Crops. Cover Crop Coaching LLC. Accessed March 17, 2017. https://ag.purdue.edu/hla/fruitveg/Presentations/no-till_cvr6.pdf. Hesselgrave, Barbara. Soil Solutions. Erosion Control: The Journal for Erosion and Sediment Control Professionals. September-October 2017. Pp. 38-47. Horton, Ned. Quivira Vineyards. Personal interview. September 6, 2017. Ingham, Dr. Elaine. Compost Tea in Plant Growing Systems – Vineyard Production. Accessed April 24, 2017. www.environmentcelebration.com/wp-content/uploads/2016/04/Growing-Systems.pdf. Kittredge, Jack. Soil Carbon Restoration: Can Biology Do the Job? Northeast Organic Farming Association/Massachusetts Chapter, Inc. August 14, 2015. www.nofamass.org/sites/default/files/2015_White_Paper_web.pdf. Lancaster, Brad. Bunyip Water Levels and A-Frame Levels. Harvesting Rainwater. Appendix 2. Accessed June 2017. https://www.harvestingrainwater.com/wp-content/uploads/2006/05/Bunyip-Water-Levels-and-A-Frame-Levels- Appendix-2.pdf. Landsmart. Sonoma Resource Conservation District. Chapter 7. Santa Rosa, CA, 2016. Accessed May 23, 2017. www.landsmart.org/wp-content/uploads/2016/04/Chapter-7-Roads_with_data_form.pdf. Long, Rachael F. and Anderson, John H (ANR8390). Establishing Hedgerows on Farms in California. University of California Agriculture and Natural Resources. Publication 8390. April 2010. http://ucfoodsafety.ucdavis.edu/files/26499.pdf. Magdoff, Fred and Van Es, Harold. Building Soils for Better Crops: Sustainable Soil Management. Sustainable Agriculture Research and Education (SARE). Third edition. Handbook 10. Brentwood, MD, 2009. Accessed May 9, 2017. www.sare.org/Learning-Center/Books/Building-Soils-for-Better-Crops-3rd-Edition/Text-Version. Marin Resource Conservation District. Groundwork: A Handbook for Small Scale Erosion Control in Coastal California. Accessed June 2017. www.marinrcd.org/wp/wp-content/uploads/2014/01/Groundwork-A-Handbook-for-Small-Scale-Erosion- Control-in-Coastal-California.pdf. Martinson, Tim. Erosion Control in Vineyards. Cornell University. August 16, 2012. Accessed May 2, 2017. articles.extension.org/pages/65031/erosion-control-in-vineyards. McEnhill, Don and Legge, Robert. Russian Riverkeepers. Personal interview. September 8, 2017. McGourty, Glenn. Cover Cropping Systems for Organically Farmed Vineyards. Practical Winery & Vineyard Journal. September/October 2004. Accessed April 20, 2017. www.practicalwinery.com/septoct04/septoct04p22.htm. Montgomery, David R. Dirt: The Erosion of Civilizations. University of California Press. Berkeley, CA. 2007.
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NRCS, et al. Cover Crop in Organic Systems. March 2014. www.sare.org/learning-center/sare-project-products/western-sare-project-products/organic-conservation- training/cover-crops-in-organic-systems/cover-crops-in-organic-systems. O’Geen, Anthony Toby, et al. Chapter 5: Managing Erosion in Vineyard Blocks and Avenues. University of California, Division of Agriculture and Natural Resources. Accessed July 2017. www.naparcd.org/wp-content/uploads/2014/10/Chapter5_ManagingErosionInVineyardBlocksAndAvenues.pdf. Resource Conservation District of Monterey County (RCDMC). Carmel River Watershed Stewardship Manual: A User’s Guide for Landowners and Residents. January 2013. Accessed June 2017. https://www.rcdmonterey.org/images/docs/publications/carmel-watershed-conservation-manual.pdf. Resource Conservation District of Monterey County (RCDMC). Hillslope Farming Runoff Management Practices Guide. February 2014. Accessed July 2017. https://www.rcdmonterey.org/pdf/rcdmc-hillslope-guide-rvsd-2.11.14.pdf. Rutzinger, M. et al. Climate Induced System Status Changes at Slopes and Their Impact on Shallow Landslide Susceptibility. Accessed May 31, 2017. https://www.uibk.ac.at/geographie/lidar/c3s/c3s.html. Sierra Harvest. An In-Depth Interview with Dr. Elaine Ingham – Keynote Speaker at the Food & Farm Conference. December 13, 2016. Accessed April 24, 2017. https://sierraharvest.org/an-in-depth-interview-with-dr-elaine-ingham-keynote-speaker-at-the-food-farm- conference. Skinkis, Patty. Overview of Vineyard Floor Management. Oregon State University. September 28, 2015. Accessed May 2, 2017. http://extension.org/pages/31597/overview-of-vineyard-floor-management. Southern Sonoma County Resource Conservation District (SSCRCD). Slow it. Spread it. Sink it! A Homeowner and Landowner’s Guide to Beneficial Stormwater Management. Petaluma, CA. July 2010. Accessed Aril 24, 2017. www.sscrcd.org/pdf/Slowit.Spreadit.Sinkit.vfinal.pdf. The Nature Conservancy. California Salmon Snapshots. Accessed June 15, 2017. www.casalmon.org/salmon-snapshots/restoration/garcia-river-1. Upper Salinas – Las Tablas Resource Conservation District (USLTRCD) and San Luis Obispo County Planning and Building Department. Cover Up Story Erosion Control Handbook. July 2005. USDA-NRCS. Land Evaluation and Site Assessment: A Guidebook for Rating Agricultural Lands. Second Edition. 1996. Prepared by James R. Pease and Robert E. Coughlin. Published by the Soil and Water Conservation Society. www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1047455.pdf. US Environmental Protection Agency (EPA). Agriculture Management Practices for Water Quality Protection. Watershed Academy Web. April 29, 2017. https://cfpub.epa.gov/watertrain/moduleframe.cfm?parent_object_id=1362
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US Environmental Protection Agency. BMPs and Management Measures: Structural and Nonstructural. 2011 National Tribal Water Quality Conference. Pojoaque Pueblo, NM. Accessed 2016. https://www.epa.gov/sites/production/files/2015-10/documents/thurs1_02measures_0.pdf. US Geological Survey (USGS). Landslide Types and Processes. Fact Sheet 2004-3072. Accessed June 15, 2017. https://pubs.usgs.gov/fs/2004/3072/fs-2004-3072.html. Weaver, W., Weppner, E., and Hagans, D. Handbook for Forest, Ranch & Rural Roads: A Guide for Planning, Designing, Constructing, Reconstructing, Upgrading, Maintaining and Closing Wildland Roads. Pacific Watershed Associates. Arcata, CA. January 2014. Wiest, Richard L. A Landowner’s Guide to Building Forest Access Roads. Road Construction chapter. USDA Forest Service. Radnor, PA. July 1998. Accessed July 21, 2017. https://www.na.fs.fed.us/spfo/pubs/stewardship/accessroads/construction.htm.
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Image Credits All undocumented photographs are the property of the Sonoma County Department of Agriculture/Weights & Measures. We gratefully acknowledge these additional resources:
Introduction Vineyard erosion https://www.facebook.com/RussianRiverkeeper/photos/a.117218047197.101880.45096072197/101535268451 97198/?type=3&theater
Chapter 1: General Principals of Erosion Control Erosion process wiki.ubc.ca/LFS:SoilWeb/Soil_Management/Soil_Erosion Rainsplash http://teach.albion.edu/jjn10/erosion/ Sheet, rills, gullies https://alanhamr.weebly.com/water-erosion.html Sheet/rill erosion www.missouriruralist.com/regulatory/usda-requires-more-erosion-control-field-gullies Normal/compacted soil https://360yieldcenter.com/plant-health/dont-be-fooled-by-the-dry-harvest-you-might-have-compaction- throughout-your-field/ Typical causes of erosion Upper Salinas – Las Tables RCD. Cover Story.
Chapter 2: Managing Surface Erosion from Cultivated Areas Downward spiral of soil health www.profitproag.net/past-newsletters-list/?email_id=52 Cover crop roots http://www.onpasture.com/2016/09/05/small-grains-as-forage-and-cover-crops/ Vineyard cover crop https://psuwineandgrapes.wordpress.com/2016/06/10/why-should-we-care-about-under-trellis-cover-crops/ Mycorrhizae https://image.slidesharecdn.com/nntc-ccfertility2-140127213146-phpapp02/95/cover-cropping-practices-that- enhance-soil-fertility-13-638.jpg?cb=1390858396
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Hydroseeding application www.wjbrunet.com/blog/top-level-knowledge-about-hydroseeding Erosion control blanket http://www.geosyn.co.uk/product/trinter Wood mulch http://oregonswcs.org/wp-content/uploads/2012/11/Garnier-Vineyard-mulch.jpg Erosion control blanket diagram www.nedia.com/Erosion_control_inst_slopes.html Hedgerow http://baselandscape.com/2014/02/visiting-wsu-and-lecture-on-urban-ag-and-pollinator-habitat/ Silt fence https://www.catalogclearance.com/Silt-Fence-2x100 Straw bales www.cattleyawines.com/annual-ritual-winterization-hillside-vineyard/
Chapter 3: Managing Sediment Delivery from Roads Road reshaping before/after www.pacificwatershed.com/projects/before-after-project-photos?page=3 Plugged culvert http://hurkunderground.com/services/culvert-cleaning Trash rack https://www.napawatersheds.org/app_pages/view/7893 Diversion; critical dip www.pacificwatershed.com/sites/default/files/roadsenglishbookapril2015b_0.pdf Overflow culvert www.pacificwatershed.com/projects/before-after-project-photos?page=1
Chapter 4: Managing Stormwater Runoff Sediment plume http://fmerithewlaw.com/north-carolina-erosion-and-sedimentation-pollution-control-act-and-laws/ Vegetated swale Wine Business Monthly Vineyard drainage pipe www.navarrowine.com/shop/2006-pinot-noir-mendocino
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Chapter 5: Managing Gullies and Shallow Landslides Gully http://www.theimportanceofplantsbiology.weebly.com Bioengineered willow walls http://blogs.egu.eu/geolog/2013/04/11/bioengineering-could-be-the-answer-to-dirt-free-dams Brush layering www.dot.ca.gov/design/lap/landscape-design/erosion-control/plants/brush_layering.html
Chapter 6: Pollutant Control – Managing Pesticides Vineyard spraying www.pressdemocrat.com/news/2248437-181/napa-valley-growers-start-spraying Trapping http://calag.ucanr.edu/Archive/?article=ca.v068n04p153 Row spraying https://www.evineyardapp.com/blog/2015/08/07/pesticide-use-and-their-impact-on-fruits Orchard pest traps www.clorchard.com/pestmanagementa.html
Chapter 7: Pollutant Control – Managing Nutrients Plan components https://cfpub.epa.gov/watertrain/moduleFrame.cfm?parent_object_id=1407 Orchard floor cover https://www.growingmagazine.com/fruits/orchard-floor-care-weed-control/
Chapter 8: Winterization and Sustainable Maintenance Winterized vineyard www.cattleyawines.com/annual-ritual-winterization-hillside-vineyards/ Uncovered soil www.sciencedirect.com/science/article/pii/S0048969717300797 Biochar pyrolysis Courtesy of Ned Horton, Quivira Vineyards, Sonoma County, CA
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Appendix 1: Best Management Practices Selection Matrix Existing images used.
Appendix 2: Surface Erosion Control Orchard cover http://centralvalleyfarmscout.blogspot.com/2016/12/weighing-benefits-of-cover-crops-in.html Vineyard cover crop www.ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=20500 Crimp mulch https://www.codot.gov/programs/environmental/water-quality/documents/CDOT%20Pocket%20Guide% 20122211.pdf ECB diagram www.co.la-crosse.wi.us/departments/land%20con/docs/Erosion%20mat%20Installation%20on%20slopes.pdf Hedgerow https://www.pacifichorticulture.org/articles/hedgerows-as-habitat-a-resource-guide/
Appendix 3: Road Best Management Practices Typical drawing #9; road surface shapes; rolling dip image; critical dip image; typical drawing #19a; trash rack image; typical drawing #3 www.pacificwatershed.com/sites/default/files/roadsenglishbookapril2015b_0.pdf Critical dip typical #1c http://naparcd.org/wp-content/uploads/2014/10/1c_Typical_Upgrade_Critical_dip.pdf Waterbar photo www.clearwaterforestconsultants.com Waterbar typical http://naparcd.org/wp-content/uploads/2016/06/21_Typical_Upgrade_Waterbar.pdf Water deflector photo https://www.na.fs.fed.us/spfo/pubs/stewardship/accessroads/construction.htm Water deflector typical https://www.na.fs.fed.us/spfo/pubs/stewardship/accessroads/construction.htm Channel drain photo https://www.na.fs.fed.us/spfo/pubs/stewardship/accessroads/construction.htm Channel drain typical https://www.na.fs.fed.us/spfo/pubs/stewardship/accessroads/construction.htm
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Appendix 4: Stormwater Runoff Vegetated swale photo https://stellaloufarm.com/tag/swales/ Typical www.vwrrc.vt.edu/swc/documents/html/Draft_VA%20DCR3.htm Silt fence https://kpi-fibc.com/SiltFencing.htm Energy dissipater https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices_-_Outlet_energy_dissipation Rock outfall typical www.transportation.alberta.ca/content/doctype372/production/erosionappc.pdf
Appendix 5: Gullies Check dams www.riverlink.org/wp-content/uploads/2014/01/CH-3-2CheckDams.pdf Brush layering http://icem.com.au/bioengineering-project-in-bac-kan-vietnam-sees-early-success/climate-change-1/ Brush layering diagram http://textarchive.ru/c-2858223-pall.html Willow wall www.kennebecasisriver.ca/wattle.html Live staking photo https://www.uwsp.edu/cnr-ap/UWEXLakes/Pages/resources/WiLakeshoreRestorationProject/techniques.aspx Live staking typical www.adfg.alaska.gov/index.cfm?adfg=streambankprotection.staking
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Appendix 1: Best Management Practices Selection Matrix SURFACE EROSION PRESENT CONDITIONS SUGGESTED BMPS
Bare soil Cover crops Soil movement Straw wattles Straw mulch Visible rills or gullies Straw bales Ponding water Vegetated filter strips Hedgerows Erosion control blankets ROADS PRESENT CONDITIONS SUGGESTED BMPS
Runoff/erosion of the road Reshaping the surface Plugged culverts Rolling and critical dips Waterbars Overflowing ditches Trash racks Scouring around culverts and outfalls Proper maintenance Vegetate and/or mulch avenues STORMWATER RUNOFF PRESENT CONDITIONS SUGGESTED BMPS
Ponding on roads/avenues Vegetated swale Soil movement Retention basin Diversion ditch Sediment deposition/plumes Silt fence Impacts to water quality Engineered drainage Energy dissipater GULLIES/LANDSLIDES PRESENT CONDITIONS SUGGESTED BMPS
Mass wasting Bioengineered structures Gully formation Headcut repair Check dam Slumping/sloughing of hillslope Engineered repair AGRICHEMICALS PRESENT CONDITIONS SUGGESTED BMPS
Excessive vigor or poor growth of crop Integrated Pest Management Pest/weed infestations Nutrient Management Plan Water quality protection Disease outbreak Plant, nutrient, and soil analysis Agrichemical runoff Agrichemical storage/mixing facility
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Appendix 2: Surface Erosion Control
COVER CROP
STRAW WATTLE
MULCH
FILTER STRIP
HEDGEROW
EROSION CONTROL BLANKET
STRAW BALE
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Cover Crop Grasses, legumes, forbs or other herbaceous plants established in vineyards and orchards to provide seasonal or year round ground cover for conservation purposes. Cover crops:
Prevent sheet and rill erosion. Improve water infiltration. Increase nitrogen fixation and organic matter in soil. Manage crop vigor. Provide habitat for beneficial insects. Design Considerations The entire development site should be seeded and maintained as a permanent, non-tilled cover crop. The site should also be straw mulched in critical areas prior to the rainy season. Reseeding and fertilizer should be applied to establish 85% ground cover with an average height of 6 inches or more prior to the rainy season. Use a seed mix to provide overstory (tall, fast growing plants) and understory (low growing broadleaf plants). Vineyard avenues should be maintained in cover crops. Choose species compatible with your crop and management goals. Require adequate rainfall or irrigation. Avoid using species that are on local weed lists or are hosts to Pierce’s disease. Avoid tilling too early in the spring or late in the fall; allow cover crop to set seed before tilling or mowing. Minimize tillage practices if slopes are greater than 5%. After mowing, do not remove residual dry matter. Minimize or alleviate strip spraying. Non-competitive cover crops can be established under vines or mulch bare soil under vines. Check site after each rain event. ADVANTAGES DISADVANTAGES (CAN BE MITIGATED)
Prevent erosion Depletion of soil moisture Improve soil ecosystem Potential decrease in availability of nutrients Enhance biological diversity in root zone Increased weed problems Habitat for beneficial insects Attraction of arthropod or rodent pests Regulate vine growth Potential danger of frost damage Decrease in water use/water costs Most disadvantages can be mitigated by plant selection and management methods.
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Installation Guidelines Areas to be seeded should be scarified to a depth of four to eight inches and smoothed to provide reasonably firm surface. If hydroseeding is used, a tackifier shall be applied at a rate of 75 pounds to 100 pounds per acre. In non-tillage orchards, care should be taken not to till too deeply where tree roots may have grown near the surface. Apply soil amendments as needed. For large seeded mixes with legumes, inoculate with appropriate rhizobial bacteria at rate of about eight ounces of inoculum per 100 pounds of seed. Seed can be broadcast or drilled in. In established perennial cover crops, supplemental seeding may be needed every two to five years. On slopes, apply mulch to provide temporary soil protection until seed germinates. If fall rains are not expected, light irrigation will hasten germination. A cover crop should be established within the limits of all land disturbance. The following seed mix application rates are proposed: . For vineyard blocks, rate of 80 pounds per acre. . For heavy use avenues, rate of 40 pounds per acre. Apply mulch. The type of mulch used shall be one of the following: . Straw mulch at 4,000 pounds per acre. . Wood fiber mulch at 2,000 pounds per acre. Maintenance Depending on desired outcomes and management goals, mowing or incorporation into soil will be required. Mowing or incorporation should be delayed until the cover crop has lignified but seeds are not yet viable. Incorporation of the cover crop (if desired) can be accomplished by disking or light ripping the plant material into the soil. Check after each rain event. Reseed bare areas as needed. Typical Vineyard Mixes
PERMANENT COVER CROP EROSION CONTROL HEAVY USE AVENUES Barley – 45% Creeping red fescue – 50% Bluebunch wild rye – 40% Blando brome – 25% Perennial ryegrass – 30% California brome – 33% Crimson clover – 15% Hard fescue – 20% California meadow barley – 27% Rose clover – 15% Zorro fescue – 8%
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Optimizing Cover Crop Objectives
OBJECTIVE PRACTICE COVER CROP OPTIONS WEED MANAGEMENT Increase legume seed rate by 100% to 200%, normal non-legume Sudan grass, buckwheat, seeding rates are adequate in most cases if the cover crop provides rye, oats, and legume-grass 100% ground cover in approximately 30 to 40 days after planting. mixes To ensure rapid cover crop establishment, prepare seedbed, ensure good seed to soil contact, and irrigate if needed. Planting with a drill with close spacing between seed lines (i.e. six to seven inches) is ideal to ensure an even stand, however where broadcasting methods are used, seeding rates should be approximately 50% greater than for a drilled cover crop. Maintain high percentage cereal or forb in cover crop mixtures (i.e. 50% to 75% of solo stand). BIOLOGICAL NITROGEN Use solo legume or mixed stands with high legume seeding rate Vetch species, clovers, FIXATION (80% to 100% of solo legume stand). Reduce cereal seeding rate winter peas, fava beans, (0% to 30% of solo cereal stand); inoculate legumes unless same cowpeas, and black medic Rhizobia species is already well established in soil. For maximum nitrogen release, terminate legumes at early flowering. In stands with low percent legume, the risk of nitrogen immobilization from mature cover crops is minimal when cover crop biomass contains at least 25% legume. ORGANIC MATTER Optimize cover crop biomass at termination; maintain high cereal Consider high biomass CONTRIBUTION or forb seeding rate (50% to 75% of solo stand); terminate as late cereals that frost kill (i.e. as possible without delaying planting (i.e. late flowering); minimize Sudan grass, spring oats, tillage; rotate to perennial cover crops when possible; consider etc.). Mixes work well too: high biomass cereals that frost kill (i.e. Sudan grass, spring oats, ryegrass, rye, lana vetch, etc.). Eliminate bare ground fallow. medic, sweet clover, brome, fescue, and barley ENHANCE BENEFICIAL Use broadleaf species (legume or forb) that supply nectar, consider Vetch species, red and INSECTS beneficial insect blends; allow strips or whole fields to flower crimson clover, phacelia, especially when nectar and pollen sources are scarce (i.e. spring). and buckwheat California-specific plant lists, technical notes, and implementation guides be found at Xerces’ Pollinator Conservation Resource Center. REDUCED TILLAGE/ Minimize tillage during cover crop establishment and termination; Clovers, cowpeas, rye, CONTROL EROSION relay seed at establishment; at termination consider roller ryegrass, and barley crimpers, flail mowing, strip tillage and undercutting; terminate late in cover crop development but before viable seed is formed. PLANT PATHOGEN Ensure that cover crops do not serve as alternative hosts to key soil Radish, mustards, rye, AND NEMATODE borne pathogens in crop rotation. Some cover crops are known to sorghum sudan hybrid, MANAGEMENT reduce soil borne fungal and nematode pathogens in some clover species, and barley rotations. REDUCED Select species with robust rooting ability to break up compaction Radish, sorghum-sudan COMPACTION and open channels to support root growth of subsequent cash hybrid, and sweet clover crops. Radishes that are winter killed often will leave open channels at the surface which improves infiltration, surface drainage, and soil warming.
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Straw Wattle/Fiber Roll Straw wattles are fiber filled mesh tubes that are an excellent short-term solution to controlling erosion, reducing sedimentation, and slowing stormwater runoff. Straw wattles help to stabilize slopes by shortening slope length and slowing, spreading and filtering overland flows. Design Considerations Straw wattles will provide temporary erosion protection on slopes after vegetation removal and/or soil disturbance. Cloth rolled or biodegradable fabric wattles are recommended; non-biodegradable netting is lethal to wildlife and requires removal and disposal after useful lifespan. Common applications for straw wattles include: . Erosion control and stormwater management on short slopes (less than 3:1) and hillsides. . Streambank restoration and revegetation. . As sediment traps around drainage structures. Correct installation is crucial to straw wattle effectiveness. Fail quickly, extremely heavy when saturated, and labor intensive. Not for use in high surface flow areas. Labor intensive as they require good ground contact and anchoring by trenching, backfilling, and staking. Installation Guidelines Excavate a three inch to six inch deep trench along the contour of slope where the wattle will be placed and perpendicular to sheet flow. Place wattle in the trench along the contour. If an engineer does not determine contour lines, reference Finding Slope/Contour Lines under Additional Resources. Using 2 inch by 2 inch by 24 inch wooden stakes, drive stakes through the wattle and into the ground so the stake is at least six inches in the ground and about two inches above the wattle. Put five stakes in each 20 foot long wattle. Toe stakes at 45 degrees to anchor the ends. Tightly overlap ends and stake to prevent any spaces between wattles. Run wattle ends upslope to prevent end-run of runoff and sediment. Recommended spacing: . 10% to 20% slopes = 60 feet . 20% to 50% slopes = 30 feet . Greater than 50% slopes = 10 feet Installation video: https://youtu.be/2fQzXSkkDg4.
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Maintenance Inspection is recommended to ensure that fiber rolls remain firmly anchored in place and not crushed or damaged by equipment traffic. Monitor wattles during and after storm events; remove accumulated sediment. Replace split, torn, unraveled, or damaged wattles. If removed and not replaced, dispose of collected sediment and fill trenches.
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Mulch Mulching is the spreading of a layer of straw, wood chips, or other suitable material over the soil surface. Mulching is intended to provide temporary protection while permanent vegetation becomes established. Benefits include weed suppression, promotion of vegetation establishment, erosion protection, and improvement of soil conditions. Design Considerations Mulch is suitable for application to recently disturbed soil surfaces and disturbed slopes. Key areas will be field perimeters, vineyard avenues, and steep slopes requiring cover. If using herbicides to control weeds, mulching under vines is recommended. Mulch on slopes may need to be secured using a tackifier or by crimping with heavy equipment (if adequate soil moisture is present). If soil moisture is lacking, biodegradable tackifiers can be applied to secure mulch. Apply mulch to large or small areas that have been previously seeded for grass or cover crop establishment. Apply mulch to bare soil in anticipation of a rain event. Use mulch sparingly around trees planted in clay or otherwise poorly draining soils. Mulch is intended to provide temporary protection. If using straw, use certified weed-free straw. Seed rich native grass straw may be an alternative in certain conditions. Not for use in channels or inundation areas. Apply straw mulch by hand in windy conditions. Installation Guidelines Seeded Areas
Seed disturbed soil with the appropriate mix of native grasses and forbs for the site prior to mulching. Apply straw mulch at roughly 4,000 pounds per acre or wood chips at 2,000 pounds per acre. Anchor the straw on slopes by using a dozer to punch straw up and down the slope if soil moisture is available. If soil is dry, apply an organic tackifier to anchor mulch.
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Orchard Areas
Apply mulch in four foot diameter around trees. Mulch helps retain soil moisture so monitor irrigation applications. Maintenance Inspect the site prior to and following large storm events to ensure that mulch is in place and serving its purpose. Reseed and replace mulch as needed. Monitor effectiveness and modify management practices as needed. (RCDMC 2013)
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Filter Strip Filter strips are areas of grass or other permanent vegetation which intercept contaminants from runoff. They provide a buffer between agricultural operations and waterbodies. Benefits include settling of sediments, infiltration of runoff, capture of pollutants, and decrease in velocity of runoff. The larger the width of the filter strip, the greater the water quality benefit. Filter strips can also be an aesthetic means of stabilizing field border soil and can also serve as forage, turnrows and headlands, and field access avenues. Design Considerations Most effective and useful on areas with less than 10% slopes with sheet or uniform shallow flow. Can serve as riparian corridor buffers. Filter strip should be minimum 25 feet to 50 feet in width; as slopes increase, filter strip width increases. Maintain 85% vegetative cover. Runoff should be the form of sheet flow. Installation Guidelines Should be designed to accommodate anticipated flows, slope, and soil type for maximum benefits. Width should be determined by a technical professional. Install on approximate contour. The seedbed should be prepared with tillage and smoothing. Soil amendments should be applied if needed. If legumes are included in mix, inoculate with rhizobial bacteria prior to planting. Broadcast or drill seed. Mulch the seeded area for soil protection and moisture retention. Light irrigation may be required. Protect from compaction.
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Maintenance Mow filter strip grasses several times a year to promote dense vegetative growth. For ground nesting wildlife, avoid mowing during nesting periods. Inspect and repair after storm events. If used as grassy avenue, reseed bare or disturbed areas. Exclude vehicles from filter strips during wet periods. Maintain original width and depth to maintain management benefits. When accumulated sediment decreases the filter strip effectiveness, restoration is required.
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Hedgerow Hedgerows are rows or groups of trees, shrubs, perennials, and grasses that are planted along field edges or other unused areas around a field. Hedgerows consisting of native plantings require minimal maintenance once established and provide numerous benefits. Benefits include reduced wind and soil erosion, improved soil permeability, weed suppression, increased wildlife and beneficial insect habitat, filtration of surface water, prevention of pollutant migration, and increased biodiversity. Design Considerations Appropriate between fields, along fence lines, adjacent to roads and ditches, and next to streams and creeks. Site selection is important: . Need irrigating for the first three years. . Site cannot be subject to flooding/inundation. . Not suitable for equipment use. Plant palette must be carefully selected to: . Avoid attracting pests, disease, or harmful wildlife. . Adapt to local field site conditions such as soil type, shade, competition, and herbicide drift. Plan for weed and rodent control. Cost and labor can be high during installation but will drop significantly each year. Installation Guidelines Site selection should consider access for construction and maintenance, site conditions, and surrounding land uses. Carefully plan and design the hedgerow considering the size, types of plants desired, and planting layout. Plant selection should consider species well adapted to the soil and climatic conditions of the site. Site preparation – the site should be disked to provide a good seedbed for the seeds and plants. Planting rates and irrigation will depend on site-specific conditions and desired outcomes. Incorporate a weed and rodent control plan. Maintenance Once established, hedgerows outcompete most weeds but will require yearly maintenance. Grasses should be mowed, grazed, or burned every couple of years to maintain vigor. In general, a good time to mow is after July, post nesting season. Monitor the hedgerow for pests and rodents. Irrigate as needed, especially during drought. (ANR8390)
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Erosion Control Blanket Erosion Control Blankets (ECBs) can be effective in minimizing the erosive effect of rainfall when used to cover bare or newly planted soil. Their use stabilizes the soil to protect new plantings and reduces the potential for introducing sediment into runoff. The main purpose is to provide initial erosion protection until the desired permanent vegetation becomes established and can provide long-term protection. Design Considerations Erosion control blankets can be applied on any slope where the soil has been disturbed and when slope is too steep (3:1 or greater) for straw mulch to be effective. Coir should be installed over straw mulch over seed on all slopes 2:1 to 3:1. Effective for soil stabilization on steep to moderate slopes and drainage ditches or swales that are to be planted or seeded. Increase water infiltration into soil. Protect seed mixes from being eroded. Increase retention of soil moisture and reduce erosion. Excellent short and long-term temporary erosion control when properly installed. Ensure full contact between soil and ECB. Remove clods, rocks, vegetation, and debris. Should not be used where final vegetation will be mowed. Biodegradable materials only; no removal necessary.
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Installation Guidelines Prepare soil before installing erosion control blankets (ECBs), including any soil amendments; seed the area.
Begin at the top of the slope by anchoring the ECBs in a six inch deep by six inch wide trench with approximately 12 inches of ECB extended beyond the upslope portion of the trench. Backfill and compact the trench after stapling. Apply seed to compacted soil and fold remaining 12 inches portion of ECB back over seed and compacted soil. Secure ECB over compacted soil with a row of staples/stakes spaced approximately 12 inches apart across the width of the ECB. Roll the ECBs down or horizontally across the slope. ECBs will unroll with appropriate side against the soil surface. All ECBs must be securely fastened to soil surface by placing staples/stakes in appropriate locations as shown in the manufacturer’s instructions. (Reference figure 1 in diagram). The edges of parallel ECBs must be stapled with an approximately two inch to five inch overlap, depending on ECB type. (Reference figure 2 in diagram). Consecutive ECBs spliced down the slope must be placed end over end (shingle style) with an approximate three inch overlap. (Reference figure 3 in diagram). Staple through overlapped area, approximately 12 inches apart across entire width of the ECB. (Reference figures 4 and 5 in diagram). Secure ECB with 12 inch to 18 inch staples or two by four length ripped stakes. Stakes are preferred for biodegradability. *NOTE: In loose soil conditions, the use of staple or stake lengths greater than 12 inches may be necessary to properly secure the ECBs. (DOT) Maintenance Monitor before, during and after storm events. Remove sediment deposits when deeper than two inches. Repair or replace all damaged materials. Recompact/repair all soil washout areas.
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Straw Bale Sediment Trap/Check Dam A straw bale sediment trap is a temporary catch basin consisting of a row or more of entrenched and anchored straw bales. The purpose is to intercept and detain small amounts of sediment to prevent transport from the site. Straw bales function by decreasing water velocity and detaining sediment- laden surface runoff. Design Considerations Only for short duration and small drainage areas; tend to fill to capacity after small storms and may blow out in large storms. Ponding above the bales can occur rapidly due to low flow through rate of the bales. Overtopping and bypass of the bales can cause significant damage to the site. Should be used on nearly level ground and placed at least 10 feet from the toe of any slope. The barrier should be placed on contour. Straw bales should never be used in streams or in swales where washout is possible. Straw bales should not be used in areas that prevent the full and uniform anchoring of the barrier. Bales have a short period of usefulness not to exceed three months. Bales should be placed with the twine or cord on the side, not the bottom of the bale. Provide good access for cleanout of sediment during maintenance. Installation Guidelines Smooth construction area to provide a nearly level zone. Excavate a trench to the proper dimensions. The trench should be long enough that the end bales are somewhat upslope of the sediment pool to ensure that excess flows go through and over the bales and not around the bales. Place each bale end to end in the trench so the bindings are oriented around the sides. Anchor the bales by driving two 36 inch long, 2 inch by 2 inch hardwood stakes through each bale at least 18 inches into the ground. Drive the first stake toward the previously laid bale to force the bales together. Wedge loose straw into any gaps between the bales to trap sediments. Backfill and compact excavated soil against the bales to ground level on the downslope side and to four inches above ground on the upslope side.
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Maintenance Inspect after each storm event. Remove sediment buildup after it has accumulated to half the original capacity. Repair any damages immediately.
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Appendix 3: Road Best Management Practices
RESHAPE ROAD SURFACE
ROLLING AND CRITICAL DIP
WATERBAR
WATER DEFLECTOR
CHANNEL DRAIN
TRASH RACK
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Reshaping the Road Surface Roads and their associated ditches, cutbanks, fill slopes, and stream crossings impact the natural drainage patterns of the landscape. Roads along riparian areas may result in sediment delivery to streams, a major environmental concern for water quality. Road surface design can significantly address and minimize erosion and sediment pollution from roads. The construction, reconstruction, and maintenance of roads are important and complex subjects beyond the scope of this Guide. It is recommended that you consult the Handbook for Forest, Ranch & Rural Roads prior to any road construction or modification. Professionally engineered roads and avenues are recommended. This Guide covers a few important techniques that, if properly implemented, can result in multiple benefits including: Reduced annual maintenance. Reduced erosion. Reduced sedimentation to water courses. Improved drainage. Improved reliability. Reduced costs. Design Considerations Outsloped, insloped, and crowned roads have site-specific requirements. It is critical to properly design road surfaces to minimize erosion of the roadbed, ditch, cutbank, and fill slopes, while minimizing sediment delivery to streams. Berm removal is one of the simplest, most effective methods of controlling water on road surfaces. Storm-proofing roads by dispersing surface drainage prevents sedimentation, water diversion, or failure of road structures. Rocked roads and avenues are preferred; if rock is impractical, roads and avenues must be vegetated. Disconnect roads and avenues from streams. Do not outfall directly to a watercourse or unstable areas. Maintenance regime is critical. Installation Guidelines A professional engineer or rural road erosion control specialist should be consulted when reshaping roads.
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Maintenance Install waterbars before wet weather. Restrict vehicular travel after installation. Clear debris from culverts and ditches: repair as needed, remove sediments, and leave vegetation growing in ditches to provide filtration and prevent erosion. Remove berms. Seed and mulch exposed areas. Reshape areas and maintain as needed throughout winter. Check drainage structures for proper function. Install and clean trash racks. Prohibit use of wet avenues during the rainy season. Immediately address any erosive areas.
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Rolling Dip/Critical Dip Rolling dips are smooth, angled depressions constructed in the roadbed. They are designed to drain road surface runoff away from the roadbed as quickly as possible. Unlike waterbars, rolling dips are meant for active roads. Rolling dips are usually used on outsloped roads to drain road surface runoff to the outside of the road. While they may be used for insloped or crowned roads, the goal of effective drainage is to disperse rather than collect and concentrate road runoff. A critical dip is similar to a rolling dip. Critical dips are located at a culverted stream crossing and are designed to act as overflow structures to prevent stream diversions. Critical dips should be built where stream diversion potential is high. These structures should be built on the down gradient side of the crossing to avoid compromise of the culvert or road fill. Dips should be used on low and moderate grades, and may be used on high or low traffic conditions. Design Considerations Not used on steep grades (greater than 12%). Not to be installed along curves. Need occasional repair or reshaping. Usually built perpendicular to the road alignment, with a cross slope of 3% to 5% greater than the road grade. Rolling dip spacing, effect on hydrologic connectivity, and factors influencing discharge points are best determined by a professional engineer or a rural roads erosion control specialist.
Installation Guidelines Construction involves vegetation grubbing and removal, rough grading, final grading, and compaction to excavate and construct the dip; installation of riprap as needed in the dip across the road and also along the downslope surface of the road. A professional engineer or rural roads erosion control specialist should be consulted when reshaping roads.
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Waterbar Waterbars are low relief mounds that disperse runoff from the road before it becomes sufficiently concentrated to cause erosion. This BMP may reduce hydrologic connectivity of a road segment when properly installed and maintained. Waterbars are used to direct runoff to a well vegetated area or sediment basin and for very low traffic roads or seasonal roads only. Waterbars should break up slope length, diverting water to vegetated areas. Design Considerations Typically installed on sloped roads or avenues. For unsurfaced seasonal roads with little/no traffic and/or no wet season use. Not for use on high traffic roads. Driving over a waterbar destroys its effectiveness. Discharge to a stable area, on downslope side of access road or right of way. Never discharge to a watercourse. 2% to 4% maximum gradient is recommended. High maintenance. Inspect after each rain event or more often as needed; repair damages immediately after rain events. Waterbars should not be more than 100 feet apart or 50 feet apart for steeper slopes. Install at 30 degrees to 45 degrees angle to the road alignment.
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Installation Guidelines Start at the top of the road. If more than one waterbar is planned, properly space waterbars Waterbar Spacing according to Waterbar Spacing table. ROAD GRADE SPACING The waterbar should be placed at an angle of 30 degrees to 45 degrees, relative to the road, to allow for runoff to drain from the 2% 250 feet inlet, through the trench, and into the outfall or vegetation. 5% 135 feet Dig the trench six inches to 12 inches deep below the surface of the 10% 80 feet road, and extend it beyond both sides of the road to prevent runoff 15% 60 feet from bypassing the waterbar. The trench may be deeper for roads 20% 45 feet that are steeper or that will be closed for the season. Use the excavated soil to create the downslope berm. 30% 35 feet
The uphill end of the waterbar should extend beyond the inboard ditch of the road and into an earthen berm to fully intercept any ditch flows. The outflow end of the waterbar is to be fully open and extended far enough beyond the edge of the road to safely disperse runoff onto a rocked outfall or vegetated area. After construction, seed and mulch the entire surface of the waterbar.
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Water Deflector A water deflector is a low cost, low maintenance method to deflect surface water from roads. The deflector is simply a piece of rubber belting fastened between treated timbers. Deflectors are installed and function in the same manner as waterbars, though deflectors can withstand higher traffic use. As with waterbars, runoff is deflected to an outfall or vegetated area. Design Considerations Works well on low volume and low maintenance roads. Belts bend to let vehicles pass, but diverts water off the road. Can be used on grades over 10%. Heavy equipment can damage the integrity of the belts and destroy the ability of deflectors to divert water. Discharge water to a stable area on downslope side of access road or right of way. Never discharge to a watercourse. Low cost, low maintenance. Installation Guidelines Start at the top of the road. If more than one deflector is planned, properly space deflectors according to Waterbar Spacing table. Nail the belting to two inch by eight inch boards on either side of the belt to keep it straight and hold it in the ground. The deflector should be placed at an angle of 30 degrees to 45 degrees, relative to the road, to allow for runoff to drain along the belt and into the outfall or vegetation. Dig the trench deep enough for the deflector below the surface of the road, and extend it beyond both sides of the road to prevent runoff from bypassing the deflector. Place the deflector in the trench with three inch to six inch of the belt above the road surface. Use the excavated soil to backfill the deflector. Compact soil. The uphill end of the trench should extend beyond the inboard ditch of the road and into an earthen berm to fully intercept any ditch flows. The outflow end of the deflector is to be fully open and extended far enough beyond the edge of the road to safely disperse runoff onto a rocked outfall or vegetated area. After construction, seed and mulch any exposed surfaces.
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Channel Drain Channel drains (open top/pole culverts) can be used in place of waterbars or water deflectors, are inexpensive and easy to install. These drains capture runoff and divert it to a rocked outfall or vegetated area away from the road. Design Considerations Require regular maintenance. Easily filled with sediment and rendered ineffective within a short period of time when not maintained. Not recommended for crossing streams. Should not be used in lieu of culverts. Installation Guidelines Install drains flush or just below the road surface and angled at 30 degrees to 45 degrees downgrade. More maintenance may be required as the angle approaches 10 degrees. 30 degrees to 45 degrees is often recommended but this adds length to the drain. Upper end will be the same grade as the side ditch and extend into the toe of the upslope bank. The outlet will extend beyond the road surface with adequate riprap or other material to dissipate water velocity to prevent erosion of fill material. Spacing is the same as for broad-based drainage dips. Use is limited to low water flows and to roads located on flat ground with minimal fill.
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Trash Rack Debris racks (trash racks) and debris deflectors are structural methods that protect culverts from plugging with debris and causing potential stream diversion. A trash rack may be installed where large organic debris could be mobilized in the channel causing a plug at the culvert inlet. Many different designs exist for various applications so trash rack design will be site- specific. Any design chosen should protect the inlet from plugging and maintain flow at or near the centerline of the channel. Designs that could divert flow into the streambanks upstream of the inlet should be avoided. Design Considerations Do not install trash racks near culvert inlets in fish-bearing streams or debris will accumulate and restrict fish passage. Trash racks require regular maintenance to ensure adequate conveyance and hydraulic capacity during storm events. Applicable in drainages where larger debris is present and the possibility for mobilization is high. Use where flows are not predicted to exceed design capacity but where plugging is a concern. Not recommended for culverts with an elbow. Installation Guidelines Install center to the culvert inlet and at a distance up channel of the inlet that is equal to the diameter of the culvert. A t-post trash rack can be used for any culvert less than or equal to 30 inches in diameter. The vertical post should extend at least one culvert diameter above the streambed. Culverts larger than 30 inches should be assessed for size of transported bedload to determine appropriate material needed for a single post. (Landsmart 2016) Maintenance Clear debris after storm events. Replace damaged rack immediately.
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Appendix 4: Stormwater Runoff
VEGETATED SWALE
RETENTION BASIN
DIVERSION DITCH
SILT FENCE
ENGINEERED DRAINAGE
ENERGY DISSIPATER
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Vegetated Swale/Grassed Waterway Vegetated swales or grassed waterways are designed to treat runoff through soil and plant-based filtration and infiltration that removes pollutants through natural processes. Swales are natural or constructed channels, typically broad and shallow in shape, that are planted and continuously maintained with low- growing grassy cover to convey surface water runoff at a non-erosive velocity to a stable outlet. Design Considerations Require a thick vegetative cover to function properly. Soil composition/type should be considered; performance is boosted by addition of compost to underlying soil. Susceptible to failure if not properly maintained. May not be effective or may erode if flow velocities are high. Cannot treat large areas (larger than five acres); use multiple swales for large areas. Should not be used in areas of slope instability. Maintenance is low; occasional mowing, irrigating and sediment removal may be required. Pesticides and nutrients can impair vegetation. If ponding is observed, grading may be required to restore positive drainage. Longitudinal slope should be between 2% to 4%. Installation Guidelines Calculate stormwater runoff volume and swale capacity. Determine overflow/outflow location. Do not outfall directly to a creek or stream. Dig on contour. See Additional Resources on locating contour lines. Excavated soil is placed on downhill side of the ditch, forming a berm. Seed and mulch until vegetation establishes. Where conditions warrant, additional erosion protection, rock lined channels or check dams may be used. Not for use in high flow areas. Protect area from compaction.
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Maintenance After establishment, maintain dense vegetation, reseeding and irrigating when necessary. Control undesirable weed species. Remove sediment and mow after the rainy season. Inspect and repair after storm events; reseed disturbed areas. Do not use fertilizer or spray swale vegetation when using swales for water quality.
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Retention Basin A retention basin is an engineered structure whose purpose is to capture and detain sediment laden runoff or other debris for a sufficient length of time to allow pollutants to settle out. Basins help reduce the volume, intensity, and sediment load of stormwater runoff by slowing the water down, allowing more water to infiltrate, drop out most of the sediment load and deliver better water quality leaving the field. Design Considerations Runoff is generally directed to the retention basin via a series of subsurface pipes. Basins must be appropriately sized, installed and maintained to be effective at pollutant control. Select a location for the basin that is sufficiently removed from streams to prevent overflow from delivering sediment. The overflow outlet must have an energy dissipater and not directly outfall to a watercourse. Exposed areas should be vegetated to promote filtration of runoff and provide cover from rainfall. Installation Guidelines An engineering professional should be retained to design the pipe and basin system taking into account site-specific conditions such as soil type, topography, and hydrology. The capacity of the basin shall equal the volume of sediment expected to be trapped at the site during the planned useful life or intended maintenance interval of the basin. To reduce construction costs and save space, most basins are designed to be cleared out annually. Basins should have a protected inlet. Outlet pipe should be carefully sized and anchored or spillway designed to appropriate size. Pipelines should be designed with a minimum velocity of 1.4 feet per second to prevent sediment from collecting inside the pipe. The pipe should have an anti-seep collar to prevent seepage from degrading the compacted fill surrounding the outlet. The riser should be anchored in concrete. At least one foot of berm height (freeboard) should exist above the top of the riser. An emergency spillway should be designed that is lower than the majority of the berm and appropriately anchored with rock or concrete to withstand the erosive force of overflow. Berm and basin bank slopes should not exceed 2:1. Maintenance Maintenance practices including removal of sediments and debris and vegetation management should be performed regularly, but especially before and after storm events.
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Diversion Ditch Constructed erosion control diversion ditches will collect runoff from agricultural facilities and discharge runoff to a safe and stable outlet. Purposed uses include:
Break up concentrations of water on long slopes. Collect or direct water. Intercept surface flow. Control erosion and protect water quality. Minimize potential entry of sediment to surface waters. Spread stormwater runoff to multiple low-discharge locations. Provide temporary or long-term erosion protection on newly-developed or redeveloped farmland. Design Considerations Diversions that protect agricultural land shall have a minimum capacity for the peak discharge from a 10- year frequency, 24 hour duration storm. The outlet conditions, topography, land use, cultural operations, and soil type shall determine the location of the diversion. A combination of practices may be needed to prevent damaging accumulations of sediment in the channel. Each diversion must have a safe and stable outlet with adequate capacity. The diversion outlet may be: . A grassed waterway. . A lined waterway. . A vegetated area. . A grade stabilization structure. . An underground outlet. . A sediment basin. . A rocked energy dissipater. . A level spreader. . A combination of these practices. Runoff water is to be spread, retained, or filtered at the outlet of the ditch. The outlet must convey runoff to a point where outflow will not cause damage. Diversion ditches must not be located in a wetland without a permit. Diversions should not be used below high sediment producing areas.
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Installation Guidelines Determine ditch capacity and channel stability. Minimum depth and width can be determined by following the procedures in the National Engineering Handbook, the Engineering Field Handbook, or the Agricultural Research Service Agricultural Handbook. It is recommended to utilize professional engineering services for design. The channel may be parabolic, v-shaped, or trapezoidal with 2:1 side slopes. The diversion side slopes are based on stability and access requirements for maintenance. Stabilize side slopes with seed and mulch or line with rock. The top of the constructed ridge at any point must not be lower than the design depth plus the specified overfill for settlement. If movement of sediments into the channel is a problem, include extra capacity for sediment accumulation in the design and instructions for periodic removal. Diversions incorporating an outfall must include energy dissipaters. Install vegetative outlets before diversion construction to ensure establishment of stable vegetative cover in the outlet channel. Maintenance Inspect periodically, especially following significant storms. Promptly repair or replace damaged components as necessary. Maintain existing vegetation. Redistribute sediment as necessary to maintain the capacity of the diversion. Prevent equipment within the channel.
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Notes: 1. Flowline slope shall be 2% - 4%. 2. Diversion ditches shall be seeded, mulched, and covered with jute netting which shall be securely anchored in place.
Install trash rack
Original ground
12” riser Rock slope protection around drop inlet only
Cutoff collar PE storm drain
Notes: 1. Flowline slope and diversion ditches shall be 2% - 4%. 2. Diversion ditches shall be seeded, mulched, and covered with jute netting which shall be securely anchored in place.
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Silt Fence A silt fence is a temporary linear sediment barrier of permeable fabric designed to intercept and slow the flow of sediment-laden sheet flow runoff. Silt fences allow sediment to settle from runoff before water leaves the site. Design Considerations Appropriate applications: . Below the toe of exposed and erodible slopes. . Downslope of exposed soil areas. . Around temporary stockpiles. . Along streams and channels. . Along the perimeter of the project. Not effective unless trenched and keyed in to a marked line at the base of the silt fence. Not intended for use as mid-slope protection on slopes greater than 25%. Must be maintained. Must be removed and properly disposed. Not for use below unstable slopes or landslides. Not for use in streams, channels, drain inlets, or anywhere flow is concentrated; sheet flow only. Not used to divert flow. High failure rate on slopes longer than 50 feet. Slope of area draining to the fence shall be less than 1:1. Limit to locations suitable for temporary ponding or deposition of sediment. Life span generally limited to five months to eight months depending on site conditions. Multiple silt fences can be used for longer slopes and larger projects. Installation Guidelines Layout the fence line parallel to contour. Silt fences should be at least three feet from the toe of a slope. Dig a trench 12 inches to 24 inches wide and 12 inches deep. Bottom of the fence shall be keyed-in a minimum of 12 inches; the bottom 12 inch should be placed in the trench in an “L” shape with a six inch horizontal flap and a six inch vertical rise. The last eight feet to 10 feet of the fence should be turned up slope at 45 degrees. Stakes shall be spaced at a maximum of eight feet and be positioned on the downslope side of the fence. Maintenance Inspect during and after every storm event. Repair gaps, tears, and other damage. Remove accumulated sediment.
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Engineered Drainage Engineered subsurface drainage pipes can be designed and installed to collect surface runoff. When soil infiltration capacity is exceeded, surface runoff enters the drainage pipes at drop inlets installed flush with the ground surface in vine rows. The inlets are spaced close enough to capture runoff before it becomes sufficiently concentrated to cause erosion. The pipes discharge to surface outlets through energy dissipaters which capture any sediment. Design Considerations Cost-effective in settings with a permanent field configuration and should only be planned and implemented with guidance from a qualified professional. Must be designed with a safe downstream outlet. Pipes can be solid or perforated. If perforated pipe is used, then filter fabric and drainage rock also are installed to avoid sediment being entrained into the pipe. Prior to implementation, a professional engineer should determine that storm runoff would not increase as a result of pipe usage and that the outfall does not discharge into an unstable area. Installation Guidelines Installation must follow engineered plans developed by a professional. The trench should be dug deep enough that normal farming practices and replanting the vineyard in the future will not harm the pipe. Once solid pipe is placed in the trench, concrete collars should be installed around the pipe, and it should be covered with native material and compacted to 90%. Perforated pipe installation differs in that filter fabric and drain rock are installed in the trench to avoid sediment from entering into the pipe. Inlets should have sediment traps, be surrounded by a vegetated buffer, or have a physical barrier such as straw wattles installed in order to prevent migration of sediment into the piped system. Outlets must be stable for anticipated design flow conditions from the underground outlet. All outlets must have animal guards to prevent entry. Maintenance Inspect after storm events to ensure all structures, including outlet, remain clear. Repair or replace any damaged structures. Repair any eroded areas. Remove accumulated sediment from sediment collars at inlets.
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Energy Dissipater An energy dissipater is a structure at the outlet of a culvert or drain which reduces the velocity of water after it leaves the drain. This is very important for protecting the slope below the outlet from erosion. Design Considerations All pipe outfalls should have scour protection to minimize sediment delivery downstream. The size of the dissipater is dependent on the size of the pipe. Rock protection can be easily added to existing pipe outfalls. Do not outfall the pipe directly into a creek. Rock riprap is usually the most effective dissipater for drainage outlets. Rock should be properly sized to withstand flows and remain in place. Rock should be placed by hand to form an evenly lined depression. There should be no spaces between the rocks. Filter fabric placed between the rock and the ground will increase stability of the dissipater. Should not be used to change the direction of outlet flow. Installation Guidelines Calculate outlet velocity. Determine riprap apron length and median size for slope and volume (velocity). Construct riprap apron at 0% grade for the specified length and width. Use appropriately sized rock and fill in any gaps with smaller rock to prevent incising or scouring. Line with geotextile or filter fabric before placing stones. Rock upslope near outlet to prevent scour. Maintenance Inspect during and after storm events to see if any erosion around or below the riprap has taken place or if stones have been dislodged. Immediately repair to avoid further damage. Clean out the dissipater as necessary when approximately half of the space is filled with sediment and debris.
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Appendix 5: Gullies
HEADCUT REPAIR
ROCK CHECK DAM
BRUSH LAYERING
WILLOW WALL AND WATTLE
LIVE WILLOW STAKING
TYPICALS FOR GULLY REPAIR
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Headcut Repair The sharp break in slope gradient at the top of the gully is the headcut. Stabilizing the gully head will at least prevent the gully from growing. Design Considerations Always determine the cause of a gully before attempting repair. Restrict access and use of the area until repaired. Stop the downcutting by treating any minor contributing headcuts and/or constructing grade stabilization structures, such as willow walls or check dams, across the floor of the gully. Professional advice is strongly recommended before installing grade control structures. Consider raising the floor of the gully. This can be accomplished with bioengineered willow walls or check dams. Slope the banks of the gully back to a stable angle. This will allow vegetation to become established. If possible, plant the gully banks with native vegetation. Installation Guidelines Get professional advice for any headcut greater than three feet in height. Shape the headcut by pulling back to an angle of repose and smoothing the soil surface. Protect the new soil surface with one of the methods described on the next page.
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Methods to Protect New Soil Surface
TYPE OF HEADCUT REPAIR GULLY ACTIVITY* WATERSHED DRAINAGE AREAS COMMON REASONS FOR FAILURE SHAPING AND Low to moderate 1 to 5 acres Poor germination rate due to late REVEGETATION, or early seeding or incorrect seed HERBACEOUS COVER mixture; mulch or fabric does not WITH FABRIC stay in place; slope too steep. SHAPING AND Low 1 to 5 acres High flows tear out plants; REVEGETATION, OTHER insufficient water in dry season; TREES AND SHRUBS slope too steep; animal damage. Best used after headcut is stabilized with other methods. SHAPING AND Low to high 1 to 5 acres Sprigs planted upside down, too REVEGETATION, sparsely, not deep enough or too WILLOW SPRIGS late; sprigs too small; site too shady; insufficient water in dry season; slope too steep; animal damage. WATTLES Low to moderate 1 to 5 acres Site too shady; insufficient water in dry season; animal damage. SHAPING WITH BRUSH Moderate to high 1 to 10 acres Anchoring not secure; site too MATTRESS OR BRUSH shady; insufficient water in dry LAYERS; WILLOW WALL season; animal damage. ON SHAPED OR VERTICAL SURFACE SHAPING AND ROCK Moderate to high Any size Rock too small or too uniform; no filter under rock; rock not tightly placed; slope too steep. SHAPING AND ROCK High Any size Rock too small or too uniform; slope too steep; no filter under rock; rock not tightly placed. *Low – Headcut is shallow (less than two feet deep) and does not grow noticeably during heavy rainfall. Banks are gently sloped and mostly covered with grass, tree roots, or other vegetation. *Moderate – Headcut is shallow, but expands noticeably during winter storms. Banks are gently sloped and mostly covered with vegetation with occasional steep areas of raw, exposed soil. *High – Headcut is more than two feet deep and moves rapidly uphill during heavy rainfall. Banks are steep with little vegetation.
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Shaping and Revegetation with Herbaceous Cover In shallow gullies with low flow velocities and good sun exposure, perennial grass forms a strong, dense mat that withstands high flows. Seed mixtures that contain several kinds of grasses are recommended because they provide long-term protection and a backup in case one kind of seed doesn’t perform well at the site. Using native grass species supports native wildlife and creates a small reserve for these plants to spread into neighboring areas. Protect the seed with mulch and a natural fiber blanket. You can also try sedge and rush plugs planted 12 inches apart. Shaping and Revegetation with Other Trees and Shrubs Rooted native trees and shrubs can also be planted in headcuts and other gully points, but they are not recommended for active gullies until the headcut has been stabilized with other techniques. Since trees and shrubs are best planted during the rainy season, they won’t have a chance to grow strong root systems before storm flows, and unlike willows, you can’t bury 75% of their length and expect them to live. Coyote brush (Baccharis pilularis) is excellent for droughty sites, and sedges (Carex spp.) and dogwood (Cornus sericea) where appropriate for shady sites. Use coconut mats to protect exposed soil. Shaping and Revegetation with Sprigs Willow sprigs are an effective and inexpensive way to armor active headcuts and gully banks in small gullies, but they require soils that stay moist through the dry season. In fact, by absorbing and using water, they can help dry out an oozing headcut. Remember that willows need a sunny site to thrive. Dogwood cuttings can be used in shady areas. Willow Wattles, Brush Mattress, Brush Layering, or Willow Wall with or without Shaping These techniques, described in Chapter 5: Managing Gullies and Shallow Landslides, are excellent candidates for headcut repair. Willow wattles or fascines are best in small gullies that drain less than five acres; brush mattresses and brush layering can be used in larger gullies that drain less than 10 acres. We recommend consulting with NRCS, a local RCD, county staff, or a professional designer to help select the best method and adapt it to your site. Shaping and Rock Slope Protection Rock is commonly used to armor headcuts and nickpoints of large and highly active gullies. Unlike purely vegetative repairs, it remains in the landscape and fixes the gully in place. However, there are times when rock is needed to halt severe erosion. Seek professional assistance before using rock to repair a headcut and make sure to check if you need permits. Rock must be carefully sized and installed to stay in place during storm flows. The two most common causes of failure are piping and rock movement. Piping occurs when water finds a void between the soil and the rock layer and proceeds to wash away the soil underlying the riprap. Varying rock size and adding a layer of gravel or filter fabric below the rock allows water to percolate through without moving the soil. Filter fabric is easy to transport and install, but it can inhibit vegetation from becoming established between the rocks. Generally, filter fabric is recommended for slopes steeper than 2:1 (two feet horizontal run for a one foot vertical rise) and gravel for gentler slopes.
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Big storms can wash away the most carefully installed rock, but you can substantially reduce the chances of failure by following these guidelines: Slope the headcut back at a gentle angle. A 3:1 is best; 1:1 is minimal and should be used only on slopes less than two feet tall. Use angular, not rounded, rock. Lock large rocks tightly together with smaller ones. Placing rock is like putting together a jigsaw puzzle—you have to search through the pile to find the right rock for each spot. You should be able to walk on the rock-covered surface without wiggling individual rocks. Use dense rock. Riprap should have a minimum specific gravity of two and one-half, which means that a cubic foot of rock weighs two and one-half times one cubic foot of water. Do not use concrete chunks as they have a much lower specific gravity and can be toxic to wildlife. Size the rock according to the flow velocity. Look at neighboring drainages with similar flow velocities and see what size rock stays in place. Bigger is always better. Check the rock work frequently during the first two to three winters. If you see any cavities, rearrange the rocks securely, or pack them tightly with stones or flexible, leafy brush. Shaping, Rock Riprap, and Woody Plants Willow sprigs or other trees and shrubs planted between rocks add both wildlife value and stability to headcut repairs. The sprigs are best driven into the headcut repairs first and the rock placed around them carefully. Gravel works best under the rock instead of filter fabric when adding plants, although willow sprigs can be poked through fabric on the sides of the headcut. Diverting Flow Diverting the water from a gully can be an effective but risky way to reduce headcutting. This method is best used when the gully has clearly been caused by channeled drainage, as in the case of a road culvert focusing the runoff from a wide area into a narrow channel. Because rain and groundwater will collect in the gully even if the major flow has been rerouted, the headcut will still require armoring, although it need not be as sturdy as without the diversion. Diversion alternatives include the following:
Redistributing the runoff to better match natural runoff patterns. An example is the outsloping of ranch and forest roads to allow water to drain evenly off the entire road surface instead of through a few culverts. Reference Chapter 3: Managing Sediment Delivery from Roads of this Guide. Redirecting the runoff to a different area. Extreme care must be taken with this method because it can recreate the same problem in a new spot. It should be used only when no other options are available and then with good professional advice. The runoff should be directed to a stable area, either a natural rock outcrop or an energy dissipater. (Marin RCD) Other Complimentary Options Brush Check Dams Maintenance Inspect and monitor continuously for any sign of expansion or recurrence.
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Rock Check Dam A temporary grade control structure or dam constructed across a swale, drainage ditch, gully or area of concentrated flow. Check dams minimize the erosion rate by reducing the velocity of the stormwater. Professional advice is strongly recommended before installing grade control structures. Design Considerations For use in small, open drainage channels. Not for use in streams. For temporary or permanent swales or ditches in need of protection during establishment of vegetation. Should be designed using two cubic feet per second. For flows exceeding two cubic feet per second, check dams should be used in conjunction with other BMPs. Used to stop the downcutting of gullies. Dam height should be 24 inches maximum measured to center of the check dam. For rock check dams, drainage area shall not exceed two acres. For straw bale check dams, drainage shall not exceed one acre. Side slopes shall be 2:1 or flatter. The check dam shall be pyramid shaped to withstand scouring. Two or more check dams shall be used for drainage areas greater than one acre. Installation Guidelines Stone check dams should be constructed of graded size two inch to ten inch stone. Construct check dams perpendicular to the flows. Mechanical or hand placement shall be required to ensure complete coverage of the entire width of the ditch or swale and that the center of the dam is lower than the edges. The center of the dam must be at least nine inches lower than the outer edges. Maximum spacing between dams should be such that the toe of the upstream dam is at the same elevation as the top of the downstream dam. Most check dams require a spillway. Professional advice to determine spillway size is recommended. Provide an energy dissipater at the downstream end of the structure. The top of the check dam must be level. Key all check dams into the banks and bottom of the gully, swale, or ditch.
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Maintenance Periodic inspection is required. Sediment shall be removed when it reaches a depth of half the original dam height or before. If the area is to be mowed, check dams shall be removed once final stabilization has occurred. If not permanently stable, check dams may remain in place. After removal, the area beneath the check dam shall be seeded and mulched.
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Brush Layering Brush layering is the placement of layers of live vegetated cuttings (willow, mulefat, cottonwood, etc.) in between layers of soil. The layers are created in benches, which can require significant soil movement depending on the scale of the project. Brush layering can provide multiple benefits to failing or unstable slope. The cuttings reinforce the soil structure and root growth provides soil stability; the external growth of the cuttings serve to trap sediment and debris; and the vegetation provides erosion protection and wildlife habitat. Design Considerations Often used to stabilize slopes, including slumps, roads and streambanks. Recommended for slopes up to 2:1 in steepness. Slopes should not exceed 20 feet. Harvest and manage live cuttings following guidelines on Live Staking and Pole Planting. Install brush layers as soon as the species selected for live cuttings goes dormant. Dries excessively wet sites. Works where the toe of the slope is not disturbed. Can be installed on an existing or filled slope. Installation Guidelines Live material should be one-half inch to two inches in diameter and long enough to reach the back of the bench and still protrude from the bank. Side branches should remain intact. Mix easy-to-root species such as willow, dogwood, and cottonwood. Begin by excavating a bench along the contour at the base of the slope. Make the bench two to three feet wide and angled back into the slope 10 degrees to 20 degrees so that the outside edge is higher than the inside. Place three to five layers (20 to 25 branches per yard) of live cuttings on the bench so that the bases of the cuttings are at the inside edge of the bench and the growing tips extend from the outer edge about one foot. Backfill the bench and live cuttings with the soil excavated from the next bench. Be sure to compact the backfilled soil to ensure maximum contact between the soil and the live cuttings. Space benches three feet to five feet apart depending on the slope. The steeper the slope, the closer the spacing. Seed and mulch the bare soil between the benches after all of the brush layers have been installed.
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Install an irrigation line with emitters every one foot along the top of each brush layer. Control or divert water to prevent exposed soil from eording. Irrigate once per week or until winter rains begin. Additional irrigation the follwing summer will result in better establishment. Maintenance Replace plant failures as needed. Irrigate as needed to aid plant establishment and recruitment.
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Willow Wattle/Wall Willow wattles are long, cylindrical bundles of live cuttings that can be used for both streambank protection and to reduce erosion, aid drainage, and improve infiltration and stability of upland slopes. In streamside situations, wattles placed at the toe of the streambank can help protect against bank erosion as well as capture sediment. On upland slopes, wattles break the slope length into short runs which regulates runoff, improves infiltration and reduces erosion. As cuttings become established, they serve to further stabilize the slope and provide wildlife habitat. Design Considerations Well suited for streamside and upland slopes. When installed for steambank stabilization, will require sustained flows through the dry season to ensure establishment. They can be installed in several rows up an eroding slope where slumping or sloughing is occurring due to overland flows. Protects slopes from shallow slides (one foot to two feet in depth). Requires soil moisture or regular precipitation during the growing season. Causes minimal site disturbance when properly installed. Offers immediate protection from surface erosion. Enhances conditions for colonization of native evegetation. Serves to facilitate drainage. Installation Guidelines Harvest the cuttings according to the guidelines for pole planting and soak the cuttings for at least 24 hours. Tie together the live cuttings into bundles of 10 feet to 30 feet in length and six inches to eight inches in diameter. Be sure that the cuttings alternate in orientation and that the tips are staggered throughout the length of the wattle. Tie the wattle together with twine every two feet. Taper the ends of the wattle in case it will be joined to another one during installation. Perform any slope repairs or regrading prior to wattle installation. Dig a shallow trench on the contour approximately 10 inches wide and 10 inches deep. Excavate trenches up the slope at three foot to five foot intervals. Where possible, place one or two rows over the top of the slope to break up sheet runoff. Place the live wattle into the trench. Dig the next trench as the wattle is placed in the one below and use the excavated soil to partially cover the wattle.
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Place moist soil along the sides and top of the wattles. The tops should be slightly visible when installation is complete. Place long straw and annual grasses or install erosion control fabric between the rows if the soil is loose. Drive dead stout stakes directly through the live wattle every two feet to three feet. Leave the stakes flush with the installed wattle. Install live stakes on the downslope side of the wattle. Tamp the live stakes below and against the wattle between the previously installed stout stakes, leaving three inches to protrude above ground. Backfill the area behind the wattle forming a small bench. Maintenance Protect sprouting plants from grazing and herbicide. Irrigate as needed until established. Sprouting willow may need to be pruned to minimize potential flow obstruction. Inspect regularly for damage from animals, weather, or other sources. Check for sprouting success and replant areas as needed.
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Willow Wall
Brush Check Dam
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Live Willow Staking Live staking involves the insertion of live, rootable vegetative cuttings into the ground. When correctly prepared and placed, the live stakes will develop a root system and vegetated shoots. Willow and cottonwood are the most commonly used for live staking. The root system serves to stabilize soil, protecting it from erosion. The shoots serve to reduce velocity of flows and provide sediment deposition. Design Considerations Live stakes can be added to hard structures like riprap to provide soil stabilization. Live stakes need to be planted in an area where roots will have year-round access to water or where irrigation can be provided during the dry season for the first three to five years. Though they can be used alone, live stakes are often combined with other biotechnical practices. Live stakes can be useful in upland areas to stabilize eroding gullies and small slumps. Installation Guidelines Harvest
Stakes should be harvested during the plant’s dormant season (typically November through April). Stakes should be cut from straight, healthy two year old to five year old branches or trees. Do not clear cut a harvest stand; choose and cut select branches while leaving two-thirds of the stand. Try to harvest from the immediate area where planting; if not feasible, harvest from a stand in similar conditions. Harvest stakes that are one-half inch to two inches in diameter and three foot to four foot lengths. Make clean cuts and avoid splitting ends. Large anvil-style loppers work best. The butt ends need to be trimmed to a 45 degree angle and the tops need to be cut flat. This allows for easy bud identification and ease of planting. Trim all lateral stems from the stakes as flush as possible. Storage
Keep the stakes wet. Soak in water for 24 hours to one week. Tie stakes together into easy to manage bundles. Completely submerge the bundles in water (pond, creek, etc.).
The Land Steward’s Guide to Vineyard and Orchard Erosion Control | 128 Planting Create a pilot hole using a small sledge hammer to drive three foot to four foot concrete stake into the ground. Insert the butt end of the stake (with 45 degree cut) into the pilot hole using a dead blow hammer. Insert the stake so that 80% of its length is below ground. Trim the top if it becomes smashed or split during planting. Tamp the soil around the stake and water heavily. Plant stakes every one foot to three feet. Maintenance Protect new growth from grazing and herbicide. Monitor the site for animal, weather, or other damage. Irrigate as needed until established. Monitor sprouting success and replant as needed.
Prepare planting hole with rebar Shovel installation method
Create a small Cut and trimmed depression to live willow collect water branch .5” to 1.5” in diameter Cutting and 10” to 18” in length
Buds Soil must be firmed around live stake to avoid air pockets and drying out. Trim if more than two buds are above ground. The Land Steward’s Guide to Vineyard and Orchard Erosion Control | 129
Typicals for Gully Repair Rock Slope Protection to Prevent Gully Erosion The Land Steward’s Guide to Vineyard and Orchard Erosion Control | 130
Fill Cover Slope Construction for Gully Repair
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Soil Embankment for Shallow Landslide Repair