TABLE OF CONTENTS

Page

1.0	BACKGROUND	G-1

2.0	OVERVIEW OF URBAN STORMWATER MANAGEMENT ALTERNATIVES	G-7

2.1	Source Control Measures	G-7

2.2	Conveyance Control Measures	G-9

2.3	End of Pipe Measures	G-9

3.0	OVERVIEW OF RURAL STORMWATER MANAGEMENT ALTERNATIVES	G-12

3.1	Source Control Measures	G-12

3.2	Conveyance Controls	G-25

3.3	End of Pipe Controls	G-26

3.4	Summary	G-27

LIST OF TABLES

Table 1	Urban Stormwater Management Alternatives for Shirley's Brook/Watts Creek	G-3

Table 2	Summary of Agricultural and Rural Areas	G-12

Table 3	Summary of Rural Stormwater Management Practice	G-27

LIST OF APPENDICES

Figure 1	Urban Stormwater Management Alternatives

APPENDIX G

STORMWATER MANAGEMENT PRACTICES OVERVIEW

1.0	BACKGROUND

The following is a summary of alternative stormwater management practices used for controlling urban and rural runoff. The information presented is based on the latest literature and on Dillon's experience in the planning, design, construction and operation/maintenance of stormwater management facilities.

The first part describes the current trend in urban developments which advocates the hierarchy of preferred Stormwater Management Practices (SWMP's) as outlined in the updated (Draft) Stormwater Management Practices Planning and Design Manual (MOE, 1998):

i)	Source Controls.

ii)	Conveyance (system) Controls.

iii)	End of pipe Controls.

iv)	Miscellaneous Controls.

Figure 1 summarizes the latest techniques available to control urban runoff. The material was developed for urban area development (residential/industrial/commercial) with the philosophy that source controls be assessed first and end-of-pipe last.

Following a general description of alternative urban stormwater management practices, Table 1 summarizes the various alternatives applicable in the Shirley's Brook and Watts Creek sub- watersheds. The next part of this stormwater management chapter describes the rural stormwater management alternatives, similarly first presenting a general description followed by Table 2, which summarizes the alternatives applicable for the two sub-watersheds.

It is important to note that the ultimate selection of recommended measures is dependent on the tributary-specific and in some instances, the reach-specific characteristics, sensitivities and functionalities present within the study area.

The selection of the appropriate alternative must be based not only on technical consideration such applicability and cumulative effects, but also on acceptability by the public.

Figure 1	Urban Stormwater Management Alternatives

Table 1	Urban Stormwater Management Alternatives for Shirley's Brook/Watts Creek

(4 pages)

Table 1

Table 1

Table 1

2.0	OVERVIEW OF URBAN STORMWATER MANAGEMENT ALTERNATIVES

The following pages describe various stormwater management practices that could provide the protection and rehabilitation measures required within the study area. These SWMP's reviewed consist of both well established and new approaches.

2.1	Source Control Measures

Source controls are on-site measures that control runoff at the source of discharge. This includes all measures which treat the runoff prior to it reaching the conveyance system (storm sewers or grassed swales). In general, this involves ponding and/or infiltration on the developed area surfaces.

Rooftop Runoff

Discharge of the runoff from roof tops can be dealt with by using one or more of the following disposal techniques:

•	Use of a splash pad at the outlet of the downspout prevents erosion and spreads the runoff over the immediate area, whereby the runoff then flows overland to the conveyance system.

•	Cisterns can be used to collect the discharge from roof leaders for later use (ie., water of lawns and gardens) in an underground tank or rain barrels.

•	An additional measure to reduce the potential for downstream flooding and erosion is the use of shallow ponding areas (maximum depth 10 cm) in rear yards or at the rear lot line and should be located at least 4 m from the building to prevent additional discharge into the foundation drainage. Water is detained in the surface ponds until it evaporates or infiltrates. Ponding can be achieved in depressional areas and through the use of raised rear yard catch basins.

•	A soakaway pit is an underground infiltration trench to which the runoff is directly conveyed via the roof leader.

Foundation Drain Disconnection

Pumping of foundation drain discharges to the surface or into soakaway pits, instead of discharging into storm sewers, reduces the risk of basement flooding due to sewer backup and reduces the downstream sewer discharge quantity while increasing infiltration.

Catchbasin Restrictors

Similar to the ponding technique described for roof leader runoff in the previous section, the use of catchbasin restrictors/control orifices in urban storm sewer systems can detain stormwater on parking lots or divert flows on road surfaces, thereby delaying the entry of stormwater into the sewer system.

Lot Control

Typical lot grading standards require a minimum 2 % grade away from the building to ensure adequate drainage. In naturally flat areas, new development lot grading can be reduced to 0.5 % to create greater depressional storage, and promote recharge and evapo-transpiration. This effectively reduces runoff quantity, and with increased detainment and contact with the vegetated surface, provides water quality benefits.

Rooftop Detention

Rooftop hoppers can be raised to provide rooftop detention of stormwater on flat commercial or industrial roofs to reduce the peak flow in the storm sewers. This alternative is more suitable for new developments, rather than for retrofitting. The roof structure must be properly waterproofed and designed for the extra loading.

A maximum ponding depth of 10 mm is permitted before water can flow into roof hoppers. A total storage of 65 mm would provide control for up to the 100 year event.

Porous Paving

Infiltration through road or parking area surfaces has been suggested in the past by using porous pavements. This pavement consists of a thin layer of open-graded asphalt over a crushed-stone base. Since a key major roadway design consideration is maintenance of a dry sub-base for structural stability, porous pavement has no application on heavily traversed roads.

Although it has been applied in many Scandinavian countries, concerns have been raised in Ontario on its suitability in our climate. Requires a pilot study.

Slope Stabilization

Slope stabilization and erosion control measures, such as planting and benching, reduce sediment loading to storm drains, and downstream SWMPs and receiving watercourses.

2.2	Conveyance Control Measures

Conveyance control measures provide quantity and/or quality control of stormwater within the conveyance system between the source and outlet.

Grassed Swales

Recent concerns about water quality of urban runoff has resulted in the use of grassed swales instead of conventional curb and gutter, in urban areas. The use of grassed swales detains runoff, reduces sediment and pollutant transport, and encourages infiltration, decreasing runoff volumes.

Outlet Protection

Where there is a potential for erosion (ie., outlets of pipes, steep channel segments, shorelines, etc.), installation of channel or outlet protection using materials such as rip-rap or gabions reduces the likelihood of erosion and the resulting downstream erosion and sedimentation.

Pervious Pipe Systems

Pervious (or perforated) pipe systems located below ground level can be used to convey runoff, allowing water to exfiltrate through the pipe into the adjacent soils, thereby reducing the amount of storm runoff in the storm sewer system, and encouraging infiltration.

2.3	End of Pipe Measures

End of pipe control measures provide quality and/or quantity mitigation at or near the downstream end of the stormwater conveyance system.

Detention/Retention Facilities

Detention and retention facilities, such as dry ponds and wet ponds (which have a permanent pool) can remove a large percent of the particulate pollutants carried by urban runoff. Soluble pollutants and trace metals are more difficult to remove without additional use of biological mechanisms.

Extended detention ponds release water at a slower rate than the influent water and are designed to capture the first flush (4 hour, 25 mm storm) of runoff which usually carries the highest percent of pollutants. In Ontario, all storage facilities, wet or dry, are designed with extended (active) storage. These storage facilities provide sufficient detention to settle suspended solids and remove pollutants. Depending on the design of the pond and the duration of detention, it is possible to achieve a moderate to high rates of removal for particulate pollutants.

Underground Tanks

Underground tanks and large diameter pipes are another form of detention facilities. The purpose of these structures is to store temporarily runoff and release gradually after the peak has passed. Generally, tanks and "super pipes" are used in built-up areas requiring retrofit, where there is insufficient space available to control the runoff above ground. Maintenance costs, especially sediment removal costs can be very high.

Constructed Wetlands

Over the past twenty years, the concept of using natural or constructed wetlands to improve the quality of stormwater effluents has generated significant discussion and research. It is now generally acknowledged that wetland ecosystems have an intrinsic ability to modify or trap and hold contaminants and pollutants. Thus, polluted water flowing through a wetland can be naturally cleansed by a combination of physical, chemical and biological activities. Wetlands, natural or artificial, are one of the most effective SWMPs for water quality enhancement and, in Ontario, are designed to provide extended runoff detention which makes them effective in treatment of highly contaminated waters (ie. spills). When constructed with a sediment forebay which facilitates maintenance, wetlands provide additional sediment removal, further enhancing the water quality benefits. Sediment forebays also improve water quantity control ability. Depending on the level of water quality control, downstream erosion control can also be provided.

Although it often requires more land than conventional wet ponds, the potential benefits from increased nutrient removal makes the wetland alternative attractive.

Infiltration

Selection of the type and location of infiltration facilities requires a good knowledge of soils and groundwater conditions in the sub-watershed.

Standard infiltration basins and trenches reduce the runoff amount entering the receiving system, and increase recharge. Infiltration basins can also be designed with an underground perforated pipe collection network whereby the infiltrated runoff is collected and discharged to the receiving system. This type of SWMP provides water quality benefits, but are ineffective for water quantity control and as such, are suggested as a secondary facility.

The underlying soils should have a percolation rate not less than 15 mm/hr (60 mm/hr is recommended for infiltration basins) and the groundwater table or underlying bedrock should be at least 1 m below the bottom of the basin or trench. Depth of the storage layer should be sized to ensure a 24 to 48 hour drawdown. Pre-treatment of runoff should also be considered (ie., filter strips, oil and grit separators) to minimize the potential for clogging. Basins and trenches should not be located near septic fields.

Filters and Buffer Strips

Filter and buffer strips, often considered as a combination end of pipe/conveyance system, are natural areas (often engineered) that the runoff from small drainage areas (≤ 5 ha) is conveyed through on the way to the receiving system. The vegetation filters pollutants, encourages evapo-transpiration and reduces the velocity of the flow. Buffer strips, which are a larger scale natural area compared to a filter strip provide increased filtering and some infiltration of runoff, thus reducing the amount of runoff and the pollutant concentration in runoff.

Sand filters have been constructed in some jurisdictions in the U.S., where infiltration into the native soils was not possible. Sand filters can take numerous forms and can be constructed both above and below ground. Above ground, they can be incorporated into other SWMPs, such as into swales enhanced with check dams comprised of rock fill; ideally, runoff would back up in the ditch behind the check dam and slowly flow through the self-contained sand filter, which comprises the core of the check dam.

Alternatively, sand filters can be constructed below ground (ie., beneath a ditch or swale invert). In general, the filter area would be excavated and backfilled with layers of sand and gravel. Within the lower gravel sub-layer, a perforated pipe collection system is required, along with a trunk storm sewer to convey filtered water to the surface water receiver.

Oil and Grit Separators

Oil and grit separators were developed for use with drainage areas of less than 5 ha such as, commercial/industrial areas, parking lots and transit stations. Grit and sediment in the runoff entering the separator are settled out and oil is removed through phase separation. Oil and grit separators provide some water quality control with limited detention of stormwater runoff and no quantity control.

General designs include three chamber separators for areas ≤ 2 ha and manhole separators that treat low flows, allowing high flows to bypass the structure.

3.0	OVERVIEW OF RURAL STORMWATER MANAGEMENT ALTERNATIVES

There are a number of isolated agricultural resource and general rural resource areas located within the Shirley Brook and Watts Creek subwatersheds. Table 2 summarizes the approximate locations of the two areas.

TABLE 2

SUMMARY OF AGRICULTURAL AND RURAL AREAS

Subwatershed No.	Location	Land use scenario
W-1	Nepean, East of Eagleson Rd	Existing only
W-3	Nepean, Headwaters of Watts Creek	Existing and future
W-4	Nepean, Headwaters of Watts Creek	Existing and future
S-1	Western headwaters of Shirley's Brook	Existing and future
S-2	Western headwaters of Shirley's Brook	Existing and future
S-5	Northern headwaters of Shirley's Brook	Existing and future
S-7	Northern headwaters of Shirley's Brook	Existing and future

The following is a description of the various rural stormwater management practices applicable for the study area. The alternatives are presented under the source, conveyance and end-of-pipe headings.

3.1	Source Control Measures

In rural areas the primary concern in controlling stormwater runoff is to protect water quality in downstream receiving systems and groundwater systems. This is often achieved in rural settings through source control measures which are implemented/practiced on-site at the source of discharge. Source controls include all measures which treat the runoff prior to it reaching the conveyance system (ie., ditch, swale or tile drain) or the receiving watercourse.

Disconnection of Illegal Tile Drains

The only area within the two subwatersheds known to have tile drains is in the headwaters of Watts Creek in Nepean, (W-4).

If there are any illegal tile drains located within the study area, disconnecting those illegal tile drains decreases the amount of runoff/waste water entering the receiving system and prevents contamination (ie., bacteria, high nutrient loading).

Various alternatives to direct tile drainage, discussed in the following sections, exist to prevent contamination of stormwater and to contain, treat and/or dispose of contaminated runoff and waste water.

Proper Manure Handling and Storage

There are some annual operations in the study area, but most agriculture is crash crops or pasture. Where manure is handled, steps must be taken to avoid the contamination of surface and groundwater systems through runoff, infiltration, storage overflows and spills adding bacteria and excessive nutrients to the systems. Proper manure handling and storage prevents such occurrences and can improve/ protect water quality, along with providing a number of other benefits. Effective handling and storage systems:

•	Prevent surface water contamination and excessive nutrient loading;

•	Prevent groundwater/water supply contamination; and

•	Provide a valuable source of fertilizer and organic material for soil to improve soil quality, crop yield and reduce erosion.

Manure can be stored and handled as a solid or as a liquid. Common solid manure storage systems and the advantages/disadvantages of each method are:

•	Manure storage with bedding material (manure pack barn): prevents runoff contact, cost-effective (same building used to house livestock), contains odour and bedding promotes composting, but this method requires sufficient headroom in barn to provide 200 or more days of pack storage without removal.

•	Manure moved to covered storage: suitable when existing housing barn does not have pack storage capacity or if it is not practical to pack store with livestock type; prevents runoff contact and contains odour, but is costly (separate structure from housing barn).

•	Manure moved to open manure stack: less costly than covered storage, but requires contaminated runoff storage (larger land area), has high odours from open liquid storage of runoff, requires enclosure (lockable gates/fencing) for safety and can attract flies, other insects, birds and rodents. This method, with the runoff storage area, may be particularly suitable and cost effective when storage of other contaminated waters (ie., wash waters, silo leachate) is necessary.

Liquid manure storage systems are rare in the study area. Like the open manure stack (solid), liquid manure has the advantage of being able to store wash waters and other contaminated waters (additional liquid necessary for liquid storage systems). Liquid storages structures may be open or covered. Open storages can be constructed as a lined earthen pond, an in-ground concrete tank or an above-ground glass lined steel tank. Open storages must be sized to accommodate the manure/contaminated water and precipitation, and thus, require more land than a covered storage, but are usually about half the cost of a cover storage or less. The main disadvantage of open storage is the persistent odour. Covered storages may be in the form of a concrete tank, usually with a reinforced concrete top, or a concrete tank under a slatted barn floor (normally extends outside barn for agitation and manure removal). Covered storages are usually twice the cost of open storages, but have reduced odours during the storage period and require less space. Caution must be used with tanks directly below a barn as toxic and explosive gases may be produced, particularly when manure is agitated for removal. Both types of liquid storage facilities must be enclosed (ie. fenced, locked) for safety.

Stored liquid or solid manure may be use as a fertilizer and organic soil additive. Solid manure, unlike liquid manure, may be composted to produce a more stable material.

Proper Fertilizer Handling and Storage

Proper fertilizer handling and storage can prevent groundwater contamination through leaching and surface water nutrient loading. SWMPs to prevent water quality impacts are as follows:

•	Only store small amounts of fertilizer for short periods;

•	Store in a restricted area in an orderly fashion (clearly labelled to prevent accidents) and maintain storage containers (ie., no holes, punctures or tears);

•	Protect dry fertilizer from weather and store on a solid surface (ie. sealed concrete);

•	Contain and store liquid fertilizer on a solid surface with an adequately sized spill containment area;

•	Store away from wells (at least 90 m suggested);

•	Mix and load on a solid surface with spill containment measures.

Effective Manure and Fertilizer Application

Manure and fertilizers can provide organic matter, nitrogen, phosphorus, potassium and numerous micro-nutrients for crops when properly handled and applied. Mismanaged manure and fertilizer applications can pollute surface and groundwater systems while providing little or nor benefit to the soil or crops.

Important considerations in the application of manure and fertilizers is the amount to apply, the method of application and the time of year.

The amount of manure and/or fertilizer required should be determined based on soil tests, manure tests and determination of the nutrient needs of the crop. Excess components of manure or fertilizer can leach into the groundwater system. Liquid manure applied at a rate in excess of the soils infiltration rate or amounts beyond the storage capacity of the soil can runoff and enter surface water systems.

Manure and/or fertilizers should be applied in a manner that provides even distribution and minimal compaction. On bare soil prior to planting, it should be worked into the soil immediately to prevent nutrient losses and removal with runoff. Liquid manure should not be applied to dry, cracked fields without tillage to prevent seepage into drainage systems. As well, cultivation is suggested where preferential flow paths have developed. Manure and/or fertilizers should not be applied closer than 9 m from a surface water source or tile drain inlet.

Timing of manure/fertilizer application can greatly affect the benefits to the crop/soil and the risk to water resources. SWMPs to prevent water quality deterioration are:

•	Apply to fields immediately prior to or at time of seeding and/or early in growing season - do not apply after the main growing season when there is no growth to absorb it;

•	Do not apply manure/fertilizer when soils are saturated (ie., immediately after spring thaw) or to flood prone and high runoff areas;

•	Do not spread manure/fertilizer onto frozen, bare or snow-covered ground during winter;

•	Reduce soil erosion to minimize phosphorus and organic matter loss; and

•	Implement cover crops and residue management practices to cycle nutrients.

Prevention of Livestock Access to Surface Water Resources

Livestock operations are located mainly in or near streams and wetlands in the Shirley Brook watershed in the Klondike and Second Line road area. Unrestricted livestock can destroy shoreline plantings along waterways which protect the banks from erosive forces. Prevention of direct livestock access to surface water resources (ie., ditches, watercourses, wetlands, etc.) will reduce stream bank/shoreline erosion, allowing establishment of vegetation, and decrease downstream sedimentation. In addition, water quality will also be protected/improved by prevention of animal wastes directly entering waterways which can result in nutrient loading and faecal coliform pollution.

To prevent livestock access to surface water resources, fencing is the most economical SWMP; for streams, livestock crossings allow access to lands on both sides. Livestock watering devices, many of which are available at a moderate cost, must be implemented. Information on various options can be obtained from OMAFRA.

Proper Milkhouse Waste Management

There is very little if any dairy operation within the study area. Milkhouse wastes produced at dairy operations include detergents and phosphoric acid used for equipment cleaning, and waste milk (ie., in pipeline system). These wastes, improperly disposed of, can result in downstream nutrient loading, and decomposing milk can result in bacteria which can transmit diseases, decreasing the water quality in the system.

SWMPs to prevent deterioration of water resources due to milkhouse wastes include:

•	Addition of milkhouse waste to manure storage system (discussed in Section 1.2): cost-
effective, but increases volumes of liquid to be applied to fields (though it may be needed to dilute liquid manure systems); suitable for farms with excess existing storage capacity or farms looking at new facilities.

•	Exclusive storage of milkhouse waste in a cover tank, a fenced open tank or a fenced earthen pond; relatively high cost (separate structure from manure storage) and increase application costs; suitable for farms where combination with existing manure storage is not feasible.

•	Treatment of milkhouse waste in a trench and tank system: for small to average operations, less costly than exclusive storage, but may fail if not properly operated; requires suitable soils.

Water Well Protection

Water wells in rural areas should be suitably located away from septic beds and runoff contamination sources (ie., manure storage area, livestock pens, etc.) to prevent groundwater contamination. Measures to maintain water quality include having an adequate cover on the well, regular testing and using caution with potential pollutants in the vicinity of the well.

Proper Disposal of Dead Animals and Hazardous Wastes

A decomposing dead animal carcass can contaminate people directly, surface waters receiving runoff in contact with the carcass and by leaching to surface or groundwater systems. Proper disposal prevents degradation of ground and surface water quality.

Options for disposal are pickup by a licensed collector (preferred) or burying of the dead animal within 48 hours. For proper burial, the carcass must be placed under 0.6 m of earth away from any wells or surface water sources in soils with low permeability (restrict seepage).

Hazardous wastes should be taken to hazardous waste disposal sites as opposed to disposal in on- farm dump sites to prevent water quality impacts. On-farm dump sites can be leaching contaminants to the groundwater system and/or surface systems via runoff.

Proper Fuel Storage

Many rural properties have motor and/or heating fuel storage facilities. Leaking tanks and fuel spills can be a great threat to ground and surface water systems. The potential for fuel leaks can be decreased with the following measures:

•	Have all storage tanks installed and serviced annually by a registered professional;

•	Locate tanks at least 90 m away from wells;

•	Inspect all related equipment regularly and maintain inventory control to help determine if the system is leaking;

•	With above ground tanks, dike the area around the tank to contain spills (at least 110 % of tank volume) and regularly remove rainwater to maintain capacity;

•	With above ground tanks, pump fuel from top of tank; gravity fed tanks are illegal and are prone to leaks around hoses and nozzles; and

•	Have unused underground tanks removed according to regulations.

Proper Silage Storage

Only a few silage storage areas are located in the study area. Under good storage conditions silage poses little threat to ground and surface water resources. Poor storage conditions (ie., poor containment, excess moisture or pressure in the silo) can result in contamination of ground and surface water systems from nutrient rich silage leachate.

To prevent silage leachate contamination of water resources, the following SWMPs should be followed:

•	Store silage at least 90 m from any well and at least 150 m from surface water resources;

•	Have silage storage on impermeable soils (heavy clay) to prevent seepage to the groundwater system;

•	Perform regular inspections of silage storage structure and reline if any cracks are present;

•	Cover storage to prevent excess precipitation; and

•	Have a seepage collection system to contain and prevent spreading of leaks.

Proper Pest Management

Proper pest management to control weeds, insects and diseases can prevent ground and surface water contamination. Strategies to minimize the risk of water quality impacts include:

•	Use of biodegradable pesticides, (herbicides are counted as pesticides);

•	Reduction in the use of pesticides through:

-	aggressive crop growth to compete with weeds

-	use of cover crops as biological weed control

-	crop rotation

-	rotation of pesticides

-	selective area applications and maintenance of accurate records

-	use of tillage to control weeds

-	herbicide application after crop emergence (rather than soil applied)

-	avoidance of application of herbicides late in season when crop yields will not be affected;

•	Reduce pesticide losses:

-	avoid chemical sprayer loading near wells and surface water

-	do not fill sprayer directly from well or surface water source

-	protect surface water from spraying (ie., maintain a buffer strip between field and surface water resource)

-	avoid spraying prior to heavy rains

-	monitor application rates (follow directions closely) and accurately calibrate sprayer

-	reduce chemical drift by avoiding spraying if winds are higher than 8 km/h and by using a low spray pressure to produce larger drops or high water volumes (170 l/ha or more)

Effective Tillage Strategies

Although most farming practices involve hay and pasture, various tillage strategies could be applicable to conserve soil and improve production while addressing environmental concerns. Strategies range from "no tillage" techniques to carefully planned tilling/ploughing methods, described below, combined with proper residue management and timing to minimize impacts and maximize benefits.

Timing

Ploughing in the spring instead of fall minimizes the time the field is uncovered, thereby reducing runoff and erosion. Also ploughing during wet periods when the soil is saturated can result in soil compaction which also has water quantity and quality impacts.

Residue Management

Residue management is an important part of any tillage strategy to be used. Leaving a portion of the previous year's crop residue on the surface of the field after planting provides numerous water quantity and water quality benefits. These include:

•	reduced chemical loss to water;

•	reduced soil compaction and improved soil conditions;

•	increased infiltration;

•	reduced runoff amounts and velocities; and

•	decreased erosion and downstream sedimentation.

Effective residue management can be achieved through mulch tillage practices and may be employed with conventional tillage (to a degree), conservation tillage, and contour ploughing. Care should be taken to determine the residue levels desired, the appropriate crops and the handling methods to prevent planting delays or reduced crop yields due to poor residue management.

No Tillage/Ridge Tillage

No tillage techniques include any system where the soil is not disturbed between harvesting and planting. An example is ridge tillage where crops are planted on pre-formed ridges with minimal soil disturbance. Inter-row cultivation is done after the crops emerge to control weeds and maintain ridges. No-tillage techniques are best applied where lighter textured soils exist (ie., sands and sandy loams) that tend to be well structured and drained, though it is reported that ridge tillage allows soils to dry quickly and therefore, can be an option for more poorly drained soils.

High levels of residue that accumulate with no-tillage techniques dramatically decrease erosion and improve soil structure, improving infiltration ability and reducing runoff quantity.

Disadvantages are that the success of such methods depends on soil characteristics and high residue levels can slow soil drying and warm-up. In addition, no-tillage offers fewer options for using manure produced on the farm.

Conventional Tillage

Conventional tillage is any system that ploughs most of the crop residue into the soil, leaving less than 30 % of the crop remains on top after planting. This type of tillage is often used where heavy, poorly drained soils exist (ie., clays and clay loams) that need sufficient tillage to allow the soil to dry and warm for planting. Advantages of conventional tillage are that manure can be incorporated easily and specialized or modified machinery is not required.

Unfortunately, the low crop residue levels maintain with this method make soil vulnerable to crusting and erosion, and numerous trips on the fields and working with wet soil can cause compaction. These problems can increase runoff volumes and sediment transport, as well increasing sediment and nutrient loading downstream.

Various field drainage, planting and residue management practices can be incorporated into a conventional tillage system to decrease runoff and erosion, and improve water quality. The following measures are examples of SWMPs, discussed in other sections of this document, that can be employed:

•	Reduce trips over the field;

•	Vary tillage patterns;

•	Use crop rotation techniques and use forages in the rotation or cover crops between regular crops;

•	Reduce tillage intensity and increase residue cover through plow modifications;

•	Implement contour ploughing and contour planting;

•	Use strip crop or buffer strip cropping;

•	Terrace the field to control runoff; and/or

•	Retire areas where there is severe erosion.

Mulch Tillage (Conservation or Reduced Tillage)

Mulch tillage leaves at least 30 % or more of the crop residue on the surface. This is often achieved by methods such as chisel ploughing or discing, which breaks up the soil without completely turning it over.

Mulch tillage provides all the residue management benefits for water quality and quantity, and provides opportunity for manure usage with fewer trips over the field. This method is compatible with most soils with the exception of poorly drained clays and clay loams (ie., suitable for light to medium texture soils). This method may also be combined with other field drainage and planting strategies to maximize benefits.

Disadvantages, as mentioned previously under "Residue Management", are that planting delays or reduced crop yields can result if crop residue is not managed properly. In addition, high residue levels may require planter attachments.

Conservation tillage or reduced tillage are other terms often used for mulch tillage, being that fewer trips are made over the field.

Contour Ploughing

Contour ploughing can be incorporated into any tillage strategy and involves ploughing perpendicular to the slope of the land. This creates a series of dams that retain the water until it can infiltrate into the ground, reducing erosion by up to half during severe storms and decreasing runoff quantities. Combined with contour cropping, vegetation perpendicular to the natural flow path also acts as a filter to remove sediment and trap nutrients further protecting downstream water quality.

Proper Planning of Trips Over Fields

Increased mechanization has resulted in larger and heavier farm equipment. Large, heavy equipment run excessively over fields, especially during wet conditions, can cause soil compaction. This condition reduces the soils ability to hold water and creates numerous other problems. As a result, water quantity and quality control impacted as infiltration is decreased, runoff amounts and velocities are increased, and the erosion potential is greatly increased.

To prevent soil compaction, the following measures should be employed:

•	Avoid working on wet soils;

•	Reduce the number of trips over a field;

•	Keep the weight on individual axles to below five tonnes;

•	Use radial tires for traction (increase surface contact);

•	Use four-wheel drive tractors (better weight distribution between axles);

•	Use good crop rotation practices (include deep rooted plants or cover crops); and

•	Limit traffic to certain areas (ie., use same travel lanes each year).

Effective Planting Strategies

Crop Rotation

Crop rotation is the changing of the crops grown in a given field on an annual basis. This practice preserves soil structure and quality, as tillage depths vary with the crop being planted and different crops return and derive varying nutrients in the soil. This maintenance of the soil reduces erosion potential and improves infiltration ability, reducing the amount of runoff and sediment delivered to the receiving system.

Cover Crops

Cover crops are planted to protect the soil surface and maintain soil structure. These include a variety of grasses, legumes, brassicas and other plants such as buckwheat. Cover crops planted following the annual crop, prior to winter or when a annual crop doesn't cover sufficiently, protect the soil from erosive forces that can result in rill and gully formation and soil loss. Cover crops also reduce runoff velocity and improves infiltration ability, reducing the amount of runoff and sediment delivered to the receiving system.

Contour Cropping

Contour cropping is the practice of planting crops across the slope of the land and usually includes grass field borders. Contour cropping can be combined with other planting and storm water management techniques (ie., strip cropping) to maximize production and environmental benefits.

This method of planting slows and diverts runoff moving down the slope, increasing infiltration, and reducing erosion and runoff quantities. The vegetation perpendicular to the natural flow path also acts as a filter to remove sediment and trap nutrients improving downstream water quality.

Contour cropping can cut typical erosion rates in half and increase yields by 5 to 10 %. Combined with other strategies (ie., no till system) can reduce erosion up to 90 %.

Strip Cropping

Strip cropping uses alternating strips or sections of varying widths planted with crops that have different growth habits (ie., combination of row crops, small grains and forages). This method of planting with the close growing rows of different crops acts as a vegetative filter that traps sediment, reduces runoff amounts, runoff velocities, erosion, soil loss and downstream sedimentation, and results in increased infiltration.

Types of strip cropping include:

•	Contour strip cropping;

•	Field strip cropping;

•	Buffer strip cropping; and

•	Wind strip cropping;

Contour strip cropping combines contour cropping and strip cropping so that the alternating strips of different crops are arranged in bands at right angles to the natural slope of the land. This combination of strategies can increase the allowable slope length guidelines recommended by OMAF and can greatly reduce erosion rates.

Field strip cropping is normally implemented across the slope of the land in uniform strips with grassed field borders to protect against erosion and provide access. This method provides similar benefits to contour strip cropping.

Buffer strip cropping is useful on longer slopes and combines permanent strips of grass or forage to break up the slope. Benefits include reduced soil transport and loss through the increased filtering action of the grass or forage, reduced runoff velocities, erosion and downstream sedimentation, and increased infiltration.

Wind strip cropping is implemented on flatter lands where wind erosion can result in

soil movement and increased sediment transport in runoff. Crops are planted in a similar method to field strip cropping, but are laid out cross-wise to the prevailing wind.

Intercropping

Intercropping is the practice of growing field crops and tree crops at the same time, on the same land, in alternating rows. This method can be used to farm fragile or marginal land. Benefits include improvement soil, decreased runoff velocities and erosion, and increased infiltration.

The main disadvantage of the practices mentioned above, with the exception of crop rotation, is the inconvenience of working fields with varying crops (ie., rows of trees or cover crops between other crops).

Effective Irrigation

An effective and well managed irrigation system must consider:

•	the water holding capacity of the soil;

•	effects on water tables;

•	the amount of water needed by the crop;

•	the irrigation method best suited to the crop;

•	natural forces including forecasted rain and evapotranspiration expectations; and

•	impacts on the water taking source (ie., require permit from MOEE if removing more 50,000 litres/day).

Such measures to properly manage farm irrigation minimizes excess water application which can result in increased runoff, field erosion, downstream erosion and sedimentation.

Effective Field Surface Drainage

Good land drainage is necessary for all farm operations and can reduce the amount of surface runoff by allowing more water to soak into the soil. This subsequently reduces erosion and downstream sedimentation, increase infiltration and prevent flooding; sedimentation due to excessive field erosion can clog drains and ditches resulting in an increase in risk and severity of flooding.

Various methods that can provide effective field drainage are discussed in the following sections.

Tile Drainage and Water Table Management

Underground tile drains are perforated pipes that remove excess water from the soil providing the benefits of good soil drainage. Modern systems have outlet regulated to maintain groundwater levels near the bottom of the crop root zone, providing irrigation and reducing the amount runoff and nutrients/chemicals discharged at the outlet of the tile drain to the receiving system.

As indicated above, tile drains (especially unregulated drains) can increase chemical and nutrient loading in the downstream receiving system, disrupt groundwater systems, and increase the risk of groundwater contamination. In addition, tile drains can increase springtime flooding downstream which can consequently increase in stream erosion and sedimentation, and pose a threat to life and property.

Collection/outlet system components must be inspected regularly and kept clear of debris for efficient operation.

Terraces/Berms (Contour Farming)

Terraces and berms break up long slopes into a series of short slopes through the use of collection system, and often a berm, constructed across slope to collect and remove excess water safely from the field. Collection systems at the base of each short slope may consist of vertical pipe inlets and tile drains or grassed waterways. Spacing depends on slope, soil type, crop types, management and rainfall characteristics.

This type of system allows water on the field to be retained longer, allowing for increased infiltration and decreased runoff, nutrient/chemical loss, erosion and downstream sedimentation.

The main disadvantage is that the initial construction costs are quite high, although crop yields are shown to increase 10 to 15 % and cost recovery can occur in as little as three years. Collection/outlet system components must be inspected regularly, maintained and kept clear of debris for efficient operation.

Diversions

A diversion is a grassed channel with a supporting ridge on the lower side that is constructed across the slope at the bottom of a field to intercept drainage. This technique can be consider as a combined source/conveyance control and is particularly useful where terraces cannot be implemented due to the topography or because the land upslope is owned by someone else. This type of structure diverts runoff to where it can be safely conveyed to the outlet. This prevents additional runoff and erosion on downslope fields, and provides some water quality and quantity benefits to the runoff in the system through detainment and filtering of runoff which encourages infiltration and sediment removal.

Windbreaks, Shelterbelts and Natural Fencerows

Windbreaks and shelterbelts are bands of trees and shrubs established to shelter crops, livestock, buildings and soil, and to control snow accumulation. Natural fencerows are the volunteer growth of trees and shrubs around old fences and field borders. These SWMPs reduce wind speeds near the ground, preventing wind erosion and soil loss. This in turn, reduces particle transport in runoff and the subsequent sediment loading of receiving systems.

Windbreaks and shelterbelts should extend beyond what is being protected and are often established in a series at right angles to the prevailing or troublesome winds.

A rule of thumb is to place these bands of trees every 100 to 200 m depending on the height of the trees. More details on suitable tree species and design can be obtained from local Conservation Authorities, the Ministry of Natural Resources, and OMAF Best Management Practices publications.

Disadvantages of windbreaks, shelterbelts and natural fencerows are lost acreage, maintenance requirements, potential for delayed crop drying, potential for harbouring nuisance animals and weeds near fields or pastures, and that they may conflict with tile drains.

Marginal/Fragile Land Retirement

Marginal and fragile lands are often composed of steep slopes, knolls, and/or floodplains. Fragile lands are easily damaged by traditional farming methods which results in excessive erosion, loss of productivity and downstream water quality impacts due to sedimentation. Marginal lands may be poorly drained, extremely stony, or steep and are not profitable to farm.

Reforestation of marginal or fragile lands protects and improves the soil, and reduces runoff velocities resulting in increased infiltration and decreased erosion. As well, it may produce valuable forests and natural areas. Retirement of marginal or fragile lands to reforestation has no land use or environmental disadvantages, but can present a moderate establishment cost if not subsidized.

3.2	Conveyance Controls

Conveyance control measures provide quantity and/or quality control of stormwater within the conveyance system between the source and outlet. Potential methods are described in the following sections.

Grassed Swales/Waterways and Roadside Ditches

Grassed swales and waterways are broad, shallow channels protected from erosion by grass cover. They may serve to convey water for farm terraces and diversions, between contour rows or entering a rural area from other lands. As well, grassed swales and waterways may be constructed with tile drains along the sides to improve drainage. The use of grassed swales and waterways detains runoff, reduces sediment and pollutant transport, and encourages infiltration, decreasing runoff volumes.

To provide measurable water quality benefits, the contact between the runoff and the grassed surfaces should be maximized. Therefore, grassed swales should be shallow (0.5 m), with flat side slopes (2.5:1) and a wide bottom (0.75 m or greater). Velocities should be kept below 0.5 m/s. On farms, these waterways must be shaped to allow easy crossing by farm machinery, while being large enough to handle heavy rains without damage. Crop rows should enter the waterway at right angles.

In areas with access or driveway culverts, the culvert can be raised to act like a check dam. This allows for increased infiltration and settling of sediment and pollutants in the ponded area created by the check dam. This also minimizes velocities within the waterway, thereby preventing scour and erosion. Such culverts should be underdrained when raised to prevent a permanent pool from developing in the waterway over time.

Drop Pipe Inlets/Rock Chute Spillways

Drop pipe inlets (large pipes) and rock chute spillways (channel constructed of rock underlain with filter cloth) can be used to safely convey water down steep slopes or drops. Such structures prevent erosion of the steep area and provide rapid drainage without backwater accumulation and flooding of upstream fields or rural areas.

These types of structures do not reduce or detain runoff entering downstream systems and do not provide additional water quality benefits.

Channel/Outlet Protection

Where there is a potential for erosion (ie., outlets of pipes, chutes or tile drains, steep swale/channel segments, shorelines, etc.), installation of channel or outlet protection using materials such as rip-rap reduces the likelihood of erosion and the resulting downstream sedimentation.

3.3	End of Pipe Controls

Sediment/Water Control Basins

Control basins allow water to pond and be released slowly. This allows for particle settling and reduced downstream erosion, flooding and water quality impacts. Control basins for rural use are generally quite small and can be simply constructed by building short earthen embankments across the drainage path to detain the water. They are useful where other runoff and sediment control measures are not practical.

The outlet may consist of a perforated riser pipe structure (if there is sufficient runoff volumes) or an overflow. Size is determine based on the area being drained and the runoff characteristics. The basin and the outlet must be inspected regular and cleaned out periodically to prevent sediment accumulation and re-suspension.

The disadvantages are that control basins do not prevent erosion and soil loss in the field at the source or prevent effective nutrient/chemical loading of the receiving system.

Filter and Buffer Strips

Filter and buffer strips, often considered as a combination end of pipe/conveyance system, are natural areas (often engineered) protect the receiving system from surrounding land uses. The vegetation filters pollutants, encourages evapo-transpiration and reduces the velocity of the flow. Buffer strips, which are a larger scale natural area compared to a filter strip provide increased filtering and some infiltration of runoff, thus reducing the amount of runoff and the pollutant concentration in runoff.

These strips are useful around ponds and wetlands, and along ditches/swales, watercourses and shorelines to intercept overland sheet flow. Generally, the vegetated strip filters the sheet flow prior to it being discharged to the receiving stream or drainage swale. They also serve as an erosion protection measure to prevent loss of the slope upon which they are located.

A filter strip is often combined with a level spreader which is placed perpendicular to the flow and acts like a weir. The spreader may be engineered using such a material as concrete or it may take the form of an earth berm over which the water is conveyed as sheet flow to maximize the contact area with the vegetation. The spreader and filter strip should be designed to result in a 50 to 100 mm flow depth through the vegetation during a 4 hour, 10 mm storm. Storage behind the spreader is determined based on the level of control desired.

Vegetative strips should be at least 10 to 20 m wide with a 1 to 5 % slope, the flatter the better. Wider filter strips are required where slopes exceed 5 %.

Disadvantages are lost acreage, potential for harbouring nuisance animals and weeds near fields or pastures, and that they may conflict with tile drains.

3.4	Summary

Table 3 summarizes the rural stormwater management alternatives applicable for the study area.

TABLE 3

SUMMARY OF RURAL STORMWATER MANAGEMENT PRACTICE

SWMP	Benefit	Suitability
Disconnection of Tile Drains	•	decreased runoff quantity to receiving system; increased infiltration

•	runoff detainment

•	decreased risk of surface water contamination (ie., bacteria, excess nutrients)	•	retrofit applications only applicable in one area
Proper Manure Handling and Storage	•	decreased runoff quantity to receiving system

•	decreased risk of ground and surface water contamination (ie., bacteria, excess nutrients)	•	storage can be costly to construct and land consuming, depending on the size of the operation and method best suited to the farm

•	depending on method used, can cause persistent odours

•	liquid storage facilities can present health and safety hazards

•	retrofit or new development
Proper Fertilizer Handling and Storage	•	decreased risk of ground and surface water contamination	•	retrofit or new development

•	requires dry, solid area for storage and adequate spill containment
Effective Manure and Fertilizer Application	•	decreased risk of ground and surface water contamination (ie., bacteria, excess nutrients)	•	requires organization, planning, and soil and manure testing
Prevention of Livestock Access to Surface Water Resources	•	reduced stream erosion and sedimentation

•	decreased risk of surface water contamination (ie., bacteria, excess nutrients)	•	very limited use in the study area

•	requires installation of some type of watering device

•	may require construction of a stream crossing to allow livestock access to lands on both sides of water

•	retrofit or new development
Water Well Protection	•	decreased risk of groundwater contamination (ie., bacteria, excess nutrients)

•	requires adequate location away from pollution sources and regular testing

•	retrofit or new development
Proper Disposal of Dead Animals and Hazardous Wastes	•	decreased risk of ground and surface water contamination (ie., bacteria, chemicals)

•	decreased health risk
Proper Fuel Storage	•	decreased risk of ground and surface water contamination

•	decreased health risk	•	requires proper storage facilities with spill containment and regular inspections

•	retrofit or new development
Proper Pest Management	•	decreased risk of ground and surface water contamination	•	requires organization, planning, and record keeping
Effective Tillage Strategies	•	decreased runoff quantity to receiving system; increased infiltration

•	runoff detainment

•	decreased risk of surface water contamination (ie., chemicals, excess nutrients)

•	reduced erosion and downstream sedimentation	•	requires organization, planning, and record keeping

•	may require specialized or modified equipment
Proper Planning of Trips Over Fields	•	decreased runoff quantity to receiving system; increased infiltration

•	runoff detainment

•	reduced erosion and downstream sedimentation	•	requires organization and planning
Effective Planting Strategies	•	decreased runoff quantity to receiving system; increased infiltration

•	runoff detainment

•	reduced erosion and downstream sedimentation; improved water quality	•	requires organization, planning, and record keeping

•	depending on strategy implemented, can create some inconvenience in working fields due to trees between crops or alternating rows of different crops
Effective Field Surface Drainage	•	decreased runoff quantity to receiving system; increased infiltration

•	runoff detainment

•	reduced flood risk

•	reduced erosion and downstream sedimentation; improved water quality	•	can be costly to construct, depending on method chosen, design and field area

•	collection/outlet system components requires regular maintenance to prevent sediment accumulations
Windbreaks, Shelterbelts and Natural Fencerows	•	reduced wind erosion and downstream sedimentation	•	results in decreased acreage

•	may delay crop drying, harbour nuisance animals and/or conflict with tile drains
Marginal/Fragile Land Retirement	•	decreased runoff quantity to receiving system; increased infiltration

•	runoff detainment

•	reduced erosion and downstream sedimentation	•	can involve moderate cost if reforestation is implemented, but water quantity and quality benefits will be increased, along with value as a forested natural area
Grassed Swales/

Waterways and Roadside Ditches	•	potential for decreased runoff quantity to receiving system; increased infiltration

•	runoff detainment

•	reduced erosion and downstream sedimentation: improved water quality	•	can increase mosquito breeding

•	results in decreased acreage

•	retrofit or new development
Drop Pipe Inlets/Rock Chute Spillways	•	reduced erosion and downstream sedimentation	•	can involve moderate construction costs

•	retrofit or new development
Channel/Outlet Protection	•	reduced erosion and downstream sedimentation	•	can involve moderate construction costs

•	retrofit or new development
Sediment/Water Control Basins	•	can provide water quantity control

•	potential for downstream erosion control

•	potential for spill control

•	improved water quality due to settling	•	can involve moderate construction costs

•	potential for sediment re-
suspension

•	can increase mosquito breeding

•	requires regular maintenance to prevent sediment accumulation/clogging

•	results in decreased acreage

•	retrofit or new development
Filter/Buffer Strips	•	potential for decreased runoff quantity to receiving system; increased infiltration and evapo- transpiration

•	runoff detainment

•	erosion protection and reduced downstream sedimentation; improved water quality	•	moderate cost to establish

•	results in decreased acreage

•	may require regular maintenance to prevent sediment accumulation

•	retrofit or new development

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