Planning and Development - Lot Grading
Lot Grading
The Town of Slave Lake’s Property Drainage Bylaw and the Land Use Bylaw require that all residential, commercial, industrial and institutional properties are graded by the Town’s Development Standards and Procedures.
The Town’s Development Standards and Procedures are intended to provide a uniform and consistent foundation of design for those parties interested in developing land within the Town of Slave Lake.
The Lot Grading Policy establishes the processes for all lot grading within the Town and includes compliance procedures.
Lot Grading
Flooding caused by heavy precipitation, melting snow, or runoff may pose problems for all properties. Older and newer houses and residential, commercial and industrial developments may risk flooding if proper precautions, i.e. lot grading, are not taken. The Town encourages all builders and homeowners to take preventive measures to avoid flooding. It has set out drainage and lot grading standards under the Town of Slave Lake’s Development Standards and Procedures.
Purpose
The Purpose of Lot Grading is to provide proper drainage away from buildings for the benefit of property owners. The Purpose of the Property Drainage Bylaw is to regulate drainage on private and public lands.
Lot grading shapes the earth to allow surface water runoff to flow away from building foundations and follow a pre-designed drainage path. Lot Grading:
- directs surface drainage away from structures, helping to prevent basement flooding;
- provides for controlled surface drainage discharge points and rate-of-flow entering public roads and storm sewer systems; and
- minimizes infiltration of surface water entering the sanitary sewage system.
Lot Grading Tips:
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Flood Prevention
Every year, millions of litres of water flow into the municipal drainage system from residential rooftops and indoor plumbing. Most people don’t think about how the water is collected or where it goes. It’s a different matter when a torrential storm comes, the drainage system falters, or there is water in the basement.
Water damage from flooding is inconvenient and costly. Fortunately, there are many things you can do to reduce your risk. Prevention and maintenance are the keys. Looking at your home now and fixing any problem areas before the next major rainstorm can save you a lot of grief.
The Guide to Flood Prevention contains information that can help you identify problem areas and adequately upgrade, repair or maintain your property’s drainage system. This booklet is filled with practical drainage tips and projects that you can do yourself.
Details of various projects, relative costs, and degrees of difficulty are provided throughout. Even if you prefer to hire a professional, this booklet offers knowledge and insights that may help you make a more informed choice. You should get three quotes and ask for references, especially if unfamiliar with the company or individual.
Home Drainage System
In any Town, private and public drainage systems work together to channel and move sanitary and stormwater safely away from homes and neighbourhood streets. The private system is the responsibility of residential, commercial, and industrial property owners. The municipality, in this case, the Town of Slave Lake, owns and operates the public system.
The Sanitary Sewer Main handles all water disposed of inside the home. Water from showers, toilets, sinks, dishwashers, washing machines, and floor drains is channelled to a pipe under your basement floor. This pipe is connected to a larger sanitary sewer pipe under the street or the back lane.
The Storm Sewer Main deals with roof and surface water from rainfall or snowmelt. Sloped lawns and driveways direct water from the roof and the ground to the street or the back lane. Where is the water discharged to?
Water that seeps through the ground is collected by weeping tile located at the bottom of your home’s foundation. The weeping tile is typically connected to a sump pump, which sends excess water to the surface. It is not permitted, within the Town of Slave Lake, to connect a weeping tile directly to a sewer pipe under your basement floor (see Figure 1). Instead, the weeping tile should be connected to a sump pump, directing water back onto the surface.
PUBLIC (TOWN) DRAINAGE SYSTEM
The sanitary sewer main collects sewage and “grey water” and sends it to the Town of Slave Lake’s Lagoons for processing.
We have seven (7) sewage lagoons in Slave Lake. A sewage lagoon is a large pond into which the sewage and effluent from the sewage system flows. The sewage and effluent are broken down by bacteria in the lagoon. The sun and wind also play an essential role in the working of the lagoon as they provide light, warmth, and oxygen to the water. Light, warmth and oxygen are necessary to grow bacteria and algae in the water. The algae helps the bacteria to break down the sewage and effluent.
The stormwater system collects rainwater and snowmelt and channels it via pipes or overland routes to wet and dry ponds, creeks, ravines, or directly into the Lesser Slave Lake.
Why Homes Flood
On average, the Town of Slave Lake gets 362 mm (14 inches) of rain yearly. Most of this comes in thundershowers or summer storms, which can quickly drop much water in a concentrated area. When a significant rainstorm hits, the massive volume of water can overwhelm drainage systems and cause flooding. Snow poses a similar threat in the spring if there is a rapid snowmelt.
The pressure on your home drainage and municipal drainage systems can increase during a rainstorm. The condition and capacity of these systems are equally important in managing wet weather. Blocked or broken pipes, poor lot grading, excess hail, and other factors can restrict water flow, substantially increasing the risk of flooding.
When stormwater exceeds the municipal system’s capacity, surface pooling occurs. Some excess water also finds its way into the sanitary sewer system, creating added pressure on sanitary pipes, including those exiting from homes. Since 1988, the Town of Slave Lake has required each new home to have a backwater valve to protect against sewer backup.
Lot grading must have a positive slope of 5% for at least 3.0 m (10 ft.) away from the building’s foundation or to the property line, whichever is less. Also, grading near a shared property line must not impact adjacent lots. Also, downspout extensions or splash pads, window wells (where required) and weeping tile connected to a sump pit (sometimes) are recommended.
Often, homes that flood need one or more of these components or are found to need to be in better working order. A home's location can also make a difference. For example, homes built in low-lying areas or beside lakes have a more significant flood risk, as surface and groundwater will naturally drain into these areas.
Other flood risk factors include lot elevation, water near a foundation style of home, servicing elevation, surface conditions and water drainage from neighbouring properties.
Property owner’s behaviour during a storm can also increase the risk of flooding. For example, washing clothes, taking a shower, running the dishwasher and flushing your toilets adds water to a system that may already be overloaded.
The water may need somewhere to go but up your floor drain and into your basement. This is particularly true if you do not have a backwater valve. The valve is designed to close during extreme conditions and keep outside water from getting in. When this happens, water from the inside also can’t get out.
Many people must remember to put their downspout extensions down before it rains. A long downspout extension is of no value when it’s propped up against the side of the house. If you have a sump pump, double-check that it is plugged in and the breaker is on during a storm. More than one homeowner searched for the cause of a flooded basement, only to discover that the sump pump lacked the power to perform.
Five Quick, Inexpensive Ways to Get You Started
Eavestroughs and Downspouts
On any property, the first point of defence in dealing effectively with rapid snowmelt or a rainstorm are the eavestroughs and downspouts. Just 10 mm (0.4 inches) of rain on the roof of an average-sized bungalow generates 1,200 litres of runoff. Catching water from the roof and directing it away from the house's walls are critical factors in keeping your basement dry. Eavestroughs, also known as rain gutters, are located directly below the roofline of your home. Eavestroughs catch roof runoff and channel it to downspouts, generally located at the bottom corners of the roof.
The standard residential eavestrough or downspout is four or five inches wide. It is made of plastic or aluminum, but plastic is more commonly used because it is sturdier and easier to work with. They come in one standard length but can be easily cut to the desired size. Elbows, end caps, Ts, and straight connectors are all precast, so any roof size or shape can be accommodated.
Eavestroughs and downspouts should be cleaned regularly of leaves and debris so water flow is not blocked. Special complex mesh screens can be purchased to sit on top of eavestroughs to prevent leaves and large objects from entering. You can test the effectiveness of your eavestroughs by pouring water at the end furthest away from the downspout. If water leaks out or pools at any point, you need to clean, repair or replace it.
Eavestroughs should direct water on a gentle slope down towards the downspout. Use a level inside the eavestrough to check that the downhill grade is consistent from one end of the eavestrough to the downspout. Sometimes, a sagging eavestrough can be repositioned to prevent pooling and re-establish the grade. If it cannot be repositioned, replace it.
Eavestrough leaks typically occur at joints. Fortunately, they can be repaired quickly and easily with silicone. Silicone comes in a tube and is usually clear or white. Once dry, it is water-resistant and withstands extreme temperatures. When repairing a leak, do it from the inside of the eavestrough. Make sure the surface is clean and dry before applying the silicone.
The eavestrough should be replaced if the leak is from a large hole or crack. When replacing an eavestrough or downspout, seal all connector joints and end caps with silicone.
Downspouts are hollow pipes that take water from the eavestrough and channel it to the ground. Ideally, the downspout should end in an elbow and extension, directing the water from the house towards the street or back lane. In Slave Lake, the downspout extension pipe must be on a grassed area to ensure the water is discharged and absorbed within your property. Please provide the downspout extension pipe that is not located or that water is not directed onto your neighbour’s property.
Professionals use downspout material for extensions because it is durable and convenient in channelling water away quickly. Leave the extension down constantly, or put it down whenever rain is forecast. An alternative to hard downspout material is a soft plastic extension. This extension type rolls out when it rains and can be purchased at home improvement stores. Any extension should be checked regularly for leaks and to ensure it functions properly. Some side yards are too narrow to allow for a long downspout extension. In these cases, splash pads should be used. Standard splash pads are two feet long, are made of concrete or plastic, and slope away from the wall. The downspout ends within a few inches of the splash pad, which directs the water away from the house's foundation.
Downspout extensions or splash pads should never be removed. They protect you from several potential problems. Water along the basement walls of your house can seep through tiny cracks and cause a damp, clammy basement. Left unchecked, this seepage can eventually damage the foundation of your home.
Water that seeps down your basement walls and into your weeping tile can overload the sanitary sewer system, causing a sewer backup. If you have one, it may create extra work for your sump pump and could cause pump failure under severe conditions.
Improving Lot Grading
Proper lot grading is one of the most important things you can do to prevent water from getting into your home. Since 2011, the Town of Slave Lake has had a Bylaw that requires all neighbourhood homes to be graded according to an approved lot grading plan.
Lot grading starts at your basement wall. Good eavestroughs, downspouts and extensions help improve your outdoor drainage system but can’t compensate for poor lot grading. Walk around your home and ensure a minimum slope from the wall. This includes under stairs, steps, and decks. The dirt or sod should slope down from the wall at a continuous angle for at least 1.5 to 2 metres (5 to 6 feet). If the surface is decorative rock, bark, or another porous material that lets water through easily, measure where the underlying dirt begins.
The soil at your basement wall should be higher than the ground several feet away for a proper slope. It would be best to have a positive slope of 5% for a minimum distance of 3 m or to the side property boundary, whichever is less. You can use a slope gauge (see Diagram A and Diagram B) to see if the slope angle is good.
Homemade Slope Gauge
It’s easy to make a slope gauge. Cut a 2x4 into one five-foot length and one six-inch length. Place the shorter piece vertically on the end. Place the longer piece horizontally on top. Nail or screw the end of the horizontal piece onto the end of the shorter piece. Tie or place a level on the horizontal piece, and you will be ready! See Diagram B.
Place the long end of your slope gauge against the basement wall and the shorter end on the ground. The horizontal board should be level. If it is not, add soil to the basement wall until level is achieved.
Use this process as a guide for backfilling around your home. Pack down the soil with a shovel or your foot. Check every 1.5 to 2 metres (5 to 6 feet) with your slope gauge to ensure the angle is still correct.
Backfilling underneath your stairs, steps, and decks is also essential. You can use the same angle around the rest of the house, even if the bottom stair or step is less than five feet from the basement wall.
BE KIND TO YOUR NEIGHBOURS
The sloping of your lot must follow the same rules as downspout extensions (see Chapter 3). Water should be directed to the back alley or street, not into your neighbour’s yard. This can be tricky when the space between houses is narrow. One solution is for you and your neighbour to slope towards a shared property line. This creates a typical swale that can channel water toward the alley or the street. See the drawing below.
Your property may not allow for this solution. (i.e. you may have a retaining wall or high ground at the property line). In such cases, you can create an internal swale (a slope from the house and a hill from the high ground meet in the middle of the yard) and channel water towards the alley or the street. See the drawing below.
Sometimes, a neighbour’s property may have approved grading but be lower than yours. A retaining wall along the property line is an excellent solution to this problem. It can be done before a fence or other feature you don’t want to be disturbed. The wall allows you to create an internal swale that can safely channel water away.
It is always best if neighbours can discuss and resolve many grading issues together.
Backwater Valves, Weeping Tile And Sump Pumps
Flood prevention devices like backwater valves and sump pumps can be valuable home drainage assets, but not everyone needs one. Before rushing out to buy and install these devices, consider your entire home drainage system, what type of home you have, where you live, your method of servicing, and your flooding history.
A backwater valve sits inside a home’s branch or main sanitary sewer line. Its job is to prevent sewage from returning up the line and entering the basement. It is an effective last line of defence recommended for all homes at risk of flooding.
There are two types of backwater valves. Both work well, but it is essential to install the right one. The sanitary service line entering a home needs a vented backwater valve. Branch lines coming off the main line need a non-vented valve. Depending on your home's internal plumbing, you may need more than one valve. A qualified plumber can test your system and recommend the correct installation.
During a storm, sanitary wastewater trying to flow back into a home causes the backwater valve to close its flap. This action prevents sewage from re-entering the house, but it also means water inside your home can’t get out until the valve reopens.
Backwater valves must be cleaned and maintained correctly (Chapter 6). Also, older backwater valves have metal flaps (brass and cast iron). Cast iron flappers can corrode over time, causing them to stick. Once this occurs, they should be replaced with a valve with a plastic flap.
WEEPING TILE
Weeping tile is a perforated plastic pipe that surrounds a home's foundation. It sits in a gravel bed, allowing excess groundwater to seep into it. Depending on the home's age, this water is channelled to a sump pump or the stormwater sewer system.
Remember: When the valve closes the sewer line, you should not use the toilet, sink, shower, washer, dishwasher, or anything else discharges wastewater. The wastewater will have nowhere to go except up the floor drain and into your basement.
For development before 1988, weeping tile flows were directed to the sanitary sewer main and combined sewer main. As of 1988, new development is required to direct weeping tile to the foundation service where available.
Installing or repairing weeping tile is expensive but necessary in some cases. For example, weeping tile that is collapsed or clogged by debris should be restored to prevent damage to the foundation and basement walls. Before making any decisions, you should seek professional advice from a plumber or qualified contractor.
SUMP PUMPS
The majority of homes built since 1988 have a sump pump. A working pump is essential in flood prevention, channelling groundwater out and away from the house. If your home was built after 1988, you should be aware of the condition of your pump and whether it needs replacing. A good quality pump should last around ten years, depending on how often it works and the water's acidity and dirtiness.
How do you determine whether you need to replace your pump? If so, what should you look for in a new pump?
FINDING AND TESTING YOUR SUMP PUMP
Different manufacturers have different recommendations for testing and maintaining your pump. Some recommend running the pump every two to three months, while others suggest a yearly test. Follow any recommendations provided by the manufacturer. The pump should be located in a shallow pit or sump at the lowest point in your basement. Once you’ve located the pump, you can perform a simple three-step test to ensure the pump is working correctly:
1. Check to make sure power is running to the pump circuit.
2. Pour enough water into the sump pit for the pump to begin working.
3. Check the outside pipe to ensure water flows from the discharge line outside your home. Sometimes, the pump may seem to run but not pump water.
If you test the pump and it is not working correctly:
- Check for debris blocking the suction intake.
- Listen for strange noises coming from the motor.
- Check for oil in the sump well (may indicate a failed pump seal).
- If the activating switch for the pump works on a float, check that the float is not restricted.
Depending on your problems, could you consider getting your sump pump serviced or replaced?
OTHER FACTORS
Freezing: If your pump operates during freezing weather, there is a risk of freezing and line blockage. It is best to disconnect outside hoses before winter.
Recycling: If water from your sump hose discharges too close to your foundation, the water may recycle and end up back in your system, possibly endangering your foundation and wearing out your pump.
WHAT TO LOOK FOR WHEN REPLACING YOUR SUMP PUMP?
Some essential criteria for choosing a pump are size or capacity, pump type, and horsepower. Other factors specific to your home may also influence your choice of pump, such as the volume of water your drainage system has to handle or the amount of grit in the water. Balancing your needs with how much you want to pay would be best. You can buy a cheaper pump but don’t expect it to perform as long or as well. A higher-quality pump is built from top-quality components.
Horsepower (hp)
- Minimum 1/3 hp recommended.
Size/Capacity/Performance
- Make sure to size your pump correctly to ensure excellent efficiency.
- Get information on the pump capacity (the amount of water pumped in gallons per minute) and the height and distance the water needs to travel (referred to as “head”).
- To avoid clogging, the pump should be able to pass stones of up to 10 millimetres through the pipes.
- The pumping head should be approximately 10 feet in length.
- Discharge line should be 1 1/4 inch pipe.
Standard types: submersible, pedestal, and water-powered.
- Submersible is most common.
- Pedestal type may be better in highly corrosive areas.
- Water-powered pumps are not as efficient as electric ones.
- It is a good idea to
QUALITY
Pumps are tested against general standards and rated accordingly. Before purchasing a pump, check whether the pump meets CSA standards and displays a “CSA Approved” sticker.
SUMP PIT REQUIREMENTS
If your sump pit is incorrectly sized, it will affect the pump's operation. Based on the pit's capacity, the pump is most efficient when working at its optimal flow rate.
A sump pit cover is required and should be child-proof.
Maintaining Your Home Drainage System
Regular maintenance of your home drainage system can often be the difference between staying dry and getting flooded. It is a good idea to evaluate the condition of your system—inside and out—once a year. If you find a problem, make fixing it a priority.
Remember: Most flooding on private property is caused by the failure of one or more home drainage components.
This chapter provides a maintenance checklist you should review each year. If you are unsure of what to do, call a professional.
OUTSIDE
Eavestroughs and Downspouts
- Clean leaves and debris from inside the eavestrough and downspouts.
- Tighten elbows and other connections.
- Caulk and seal any leaks.
- Repair or replace sagging, badly dented, or cracked sections.
Splash Pads and Extensions
- Reconnect any loose pads or extensions
- Replace badly dented extensions.
- Check soft plastic.
- Roll out extensions to check for leaks and to ensure they work correctly.
Lot Grading
- Check the slope from the basement wall.
- Check for settling, particularly under stairs and decks.
- Raise any low spots.
- Look for cracks or spaces on driveways, sidewalks, and patios next to the foundation wall. Caulk or waterproof where needed.
INSIDE
Foundation Walls
- Check for moisture along the walls and the floor.
- Fill and seal any visible cracks
Sump Pump
- Check for power.
- Test the pump by pouring water into the pump pit.
- Check the outside pipe to confirm the water flows towards the street or back lane.
- Check and repair any leaks in the sump pump pipe.
- Disconnect the sump pump discharge hose in winter to avoid freezing in the line.
Backwater Valve
- Open the top and clean out any debris.
- Check the flapper.
- Make sure it is moving freely.
Plumbing and Fixtures
- Maintain proper water levels in traps in floor drains and toilets to minimize odours. All that is required is pouring water into the floor drain.
Fats, Oils, and Grease — Store it, don’t pour it.
Pouring fats, oils, and grease (FOG) down your drain can cause significant problems in your home’s sewer system as the FOG solidifies in your pipes and causes sewer backup. The result can be property damage, considerable expense, and inconvenience to you and the town. Store your used fats and grease in a disposable container. When it is complete, put it in the garbage. Used cooking oil should be cooled, put into a covered plastic bottle, labelled, and put out for garbage collection. If you need to dispose of more than one litre of used cooking oil, take it to an Eco Station.
Resources that can help
Several people and organizations can help you if you are concerned or need help with your home drainage system.
The Town of Slave Lake
Planning & Development Services: 780-849-8004
Operations Department: 780-849-4107
Plumbers & Landscapers
If you want professional help correcting a drainage problem, look to professional plumbers and landscapers. Lists of plumbers or landscapers can be found online or by contacting the Better Business Bureau of Central and Northern Alberta at 780-482-2341.
The Better Business Bureau can provide company reports 24 hours a day. Regardless of whom you contact, getting three estimates and references before choosing a contractor is a good idea.
Alberta Health Services
Leaky or flooded basements may become a health risk if clean-up is not done quickly and correctly. This environmental health services unit can provide information and advice in response to inquiries about potential health risks.
Glossary of Terms
BACKWATER VALVE
A backwater valve is located in a house’s sanitary sewer line. The valve closes under pressure, preventing sewage from returning up the line and back into the home.
CATCH BASIN
A catch basin collects stormwater from the street through an open metal grate and channels it to an underground pipe. Below the street level is a trap where sand, gravel, and other material are captured for removal.
DOWNSPOUT
A downspout is a pipe length connected to an eavestrough and runs vertically from the roof to the ground.
DOWNSPOUT EXTENSION
A downspout extension is a length of pipe connected to the bottom of the downspout and running at a downward angle away from a building.
DRY POND
A dry pond is an artificial depression that captures surface runoff during significant rains. Please take a look at the definition of Wet Pond.
EAVESTROUGH
An eavestrough is attached directly below the roofline. It collects stormwater from the roof and channels it to a downspout.
FOUNDATION DRAIN
This means an exterior foundation drainage system placed outside the foundation wall near the footing, piped and connected to a sump pump that pumps the water to a discharge system.
FOUNDATION SERVICE
An underground sewer pipe that connects a private foundation drainage system (weeping tile) to a storm sewer main. This type of service is designed to collect subsurface flows and groundwater only.
GREY WATER
Grey water is the relatively clean waste from baths, sinks, washing machines, and other kitchen appliances.
INTERNAL SWALE
A swale is designed to handle surface water entirely within a property.
LOT GRADING
Lot grading is shaping and sloping the land to direct surface drainage away from buildings and towards a Town right-of-way (lane or street). It aims to benefit property owners by directing surface runoff away from buildings.
LOT GRADING PLANS
Lot grading plans are engineered drainage designs for neighbourhoods that specify design elevations, surface grades, lot types, swale locations, and other drainage-related information required for lot grading. The Town of Slave Lake approves these plans and enforces them under the provisions of the Property Drainage Bylaw.
SANITARY SERVICE
An underground sewer pipe connects a private sanitary drainage system to a sanitary sewer main. This type of service is designed to collect sewage and wastewater.
SANITARY SEWER MAIN
A sanitary sewer main collects sewage and grey water from homes and businesses and directs it to a plant for treatment.
SLOPE
A slope is any inclined portion of ground or earth that directs water in a specific direction.
SPLASH PAD
A splash pad is a concrete or plastic channel that can be attached to the side of a building and sits at an angle under a downspout. It channels stormwater from the downspout away from the building.
STORM SERVICE
An underground sewer pipe connects a private stormwater drainage system to a storm sewer main. This type of service is designed to collect surface and subsurface flows resulting from rainwater and snow melt.
STORM SEWER MAIN
The storm sewer main collects rainwater and snowmelt and channels it via pipes to creeks, ravines, dry ponds, wet ponds, stormwater lakes, wetlands, and the North Saskatchewan River.
STORMWATER
Stormwater means any surface runoff that is the result of natural precipitation.
STORMWATER MANAGEMENT LAKE
A stormwater management lake is a body of water designated to collect and contain stormwater from a surrounding area. The lake may be natural or artificial.
SUMP
A basement sump is a pit under the basement floor that collects excess groundwater from weeping tile or surrounding soil.
SUMP PUMP
A sump pump is a motorized mechanical device that keeps basements dry by pumping excess water from a sump to the surface.
SWALE
A swale is a shallow, sloped channel in the ground that moves water in a specific direction.
WEEPING TILE
Weeping tile is a perforated pipe surrounding a home's foundation that collects excess groundwater. In most homes, this excess water is released to a sump pump, which carries it to the surface.
WET POND
A Wet Pond is a stormwater facility constructed through filling and excavation that provides permanent and temporary storage of stormwater runoff.
WINDOW WELL
A window well is a corrugated metal product surrounding a basement window at or below ground level. The installation allows for a proper lot grading around the basement window.
The specific reasons a home experiences flooding must be investigated on a case-by-case basis. Possible causes could be foundation wall seepage, failure of a backwater valve or sump pump, excessive flows the sump pump cannot handle, and excessive street flooding.
2. The downspout from my eavestrough is connected to the sewer pipe. Should it be disconnected?
Yes, The town's sanitary sewer system is not designed to handle the additional burden of stormwater.
3. What is the importance of good lot grading?
Good lot grading keeps surface water away from your home and your weeping tile system. Ideally, a lot should be sloped steeply away from home to allow surface water to flow onto town property (e.g., streets and lanes) rather than a neighbouring property. A disconnected downspout and sump pump should discharge at least 15 feet away from the home to ensure water does not seep down the side of the house and into the home's weeping tile.
Because sanitary sewers are not watertight, stormwater can get into the sanitary sewer in several ways:
- at maintenance holes, through maintenance hole covers, and cracks and voids around the maintenance hole
- from the surrounding ground, through cracks or separations in the sewers and from private service connections
- from weeping tile (foundation drainage) systems at private homes and buildings, since poor lot grading contributes to weeping tile flows
- from downspouts that have been incorrectly connected to the sanitary sewer system rather than the storm sewer system.
Also, during more significant storm events, there are many more water pools on the surface than usual, which can increase the amount of water entering the sanitary sewer.
Check your lot grading. Most homes over five years have settlements around the foundation walls. Remember, downspouts only pick up roof drainage. If both houses have proper slope away and drainage swales, the downspout and sump pump discharge would be directed off the lot. Have you ever considered where your surface runoff would go if your neighbour's house were not there?
A new house built in an older area is called in-fill housing. In these cases, the builders must conform to the provisions of the Property Drainage Bylaw and the Development Standards and Procedures, which prohibit drainage onto adjacent properties. Matching the existing grade at the standard property line is standard practice for these developments. Adjacent homeowners must consider their grading.
They should know that under the Property Drainage Bylaw and the Development Standards and Procedures, new homes must have a 5% slope away from the foundation walls.
Check your lot grading and foundation drainage. Then, speak with your neighbour. Remember, surface water will follow the path of least resistance. If your grade is poor or negative, the surface water will flow toward your foundation wall, increasing the risk of basement flooding.
8. My neighbour's new sidewalk is higher, and water runs into my yard. What do you think I should do?
Adequate side-lot drainage requires the cooperation of both property owners. Check your lot grading and foundation drainage, then speak with your neighbour. Ask them if they can construct a retaining wall to catch the surface drainage or redirect the downspout discharge or sump pump discharge to force the surface drainage to flow toward the front street or back lane.
Grading Your Property
Rough Grades
This stage includes backfilling the foundation walls and shaping the lot to conform to the design of the approved Lot Grading Plan.
Lot Grading Certificates prepared at rough grade will be automatically rejected.
Final Grades
This stage includes placing topsoil to shape the lot according to the design of the approved Lot Grading Plan.
Suppose rocks, wood chips, or other porous decorative materials are planned for the final landscaping. The underlying clay base (rough grade) must be raised to final grade elevations before laying this material. It is highly recommended that the top 7 to 20 cm of the final grade is not comprised of porous material, i.e. rock, wood chips, etc., because surface water can flow through those materials.
It is also recommended that landscape contractors avoid placing these materials at the design and typical as-built locations to enable the surveyors to obtain accurate information. As-built elevations provided on bark or rock may be subject to re-certification to validate drainage functionality.
Final Grade Approval Procedure
The Owner arranges for a Lot Grading Certificate to be prepared by a qualified professional, such as an Alberta Land Surveyor.
The Lot Grading Certificate is then submitted to the Town of Slave Lake for approval.
Once the Town receives your Lot Grading Certificate from the surveyor or engineer, the Planning Department will conduct a Lot Grading Certificate Review. The review will include a comparison of the Lot Grading Certificate with the submitted and approved Lot Grading Plan, the Subdivision Design, where applicable, and the Town’s Development Standards and Procedures.
In most cases, the homeowner is responsible for final grading, but this will depend on the agreement between you and your Builder. All conditions of the development permit, including final grading, must be completed within eighteen (18) months from the decision date of the Development Permit.
Lot Grading Certificates prepared at rough grade will automatically be rejected. Only Lot Grading Certificates ready for the final grade will be accepted.
Lot Grading Certificate - Required Information
A Lot Grading Certificate MUST display the following information:
- Document Title- “Final Lot Grading Certificate”;
- ‘revised’ added to the title of the document for revised certificate submissions;
- survey or re-survey date;
- certification by a Professional acceptable to the Town of Slave Lake (i.e. Alberta Land Surveyor or a Professional Engineer) (Stamp, Seal, & Signature)
- name of the company or individual that produced the Certificate;
- legal land description and municipal address of the property;
- all structure (s)/parking pad layout;
- proposed and final grades around the structure(s), at the corners of the lot, throughout the lot, and on the property boundaries;
- invert grades of swales, if applicable;
- slope percentages around the foundation and throughout the lot;
- drainage directional arrows;
- drainage easements and Right-of-Ways;
- north arrow;
- legend; and
- reference to geodetic datum.
Lot Grading Inspections
Inspections
Within ten (10) business days of receipt of the Lot Grading Certificate and once the Lot Grading Certificate Review is complete, the Planning Department will conduct a Lot Grading Inspection.
The Town must be able to review the lot grades and compare the Lot Grading Certificate with the physical site conditions before we can issue a compliance letter. As such, during winter, inspections will not be conducted due to frost and snow, i.e., from November 1st to May 31st. The process of frost heaving can alter your lot's overall appearance, misrepresenting your actual grades.
Development Deposits will be held until the required inspection is complete and a letter of compliance or non-compliance is issued.
The landowner is not required to be present during the inspection. Please rest assured that the Town’s inspectors do not enter any buildings and will only evaluate the overall development and the lot grading to ensure compliance with the Town’s Development Standards and Procedures and the Subdivision Design Grades.
A letter will inform you that many grading changes are required if deficiencies are noted. Once the necessary grading work is completed, you must request a re-inspection by contacting the Town’s Planning Department at 780-849-8004. The Planning Department will conduct two (2) inspections of the Lot Grading at no charge to the landowner/developer. All other additional inspections required will be charged at $125.00/inspection.
The Town could ask for a new or revised Lot Grading Certificate when any of the following occurs:
- errors (incomplete or unclear information on the Lot Grading Certificate);
- discrepancies or errors in design and as-built elevations that require confirmation;
- red-line revisions to the Lot Grading Plan that are not reflected on the Lot Grading Certificate.
Should my Sod be laid before or after my Final Grade is inspected?
Final grades can be inspected at the topsoil stage OR after your sod has been laid. The Town has no preference and can inspect at either stage. However, if you choose to install sod before your inspection and your final grade fails due to deficiencies, it will likely require more work to correct the grading because you will have first to pull up your sod.
As a general rule, the acceptable amount of topsoil that should be placed on top of an approved rough grade is about 10 to 15 centimetres (4 to 6 inches), and you should follow the same slopes that your Builder has established for the rough grade.
What will happen if my Final Grade is not inspected and approved?
Suppose you choose to forego your lot grading responsibilities. In that case, your property will be filed as non-compliant as per our current Land Use Bylaw, and you may experience monetary fines, delays in house sale transactions, or drainage disputes with your neighbours.
Infill Development
Infill development often presents unique challenges that require specific attention. A proposed Lot Grading Plan must accompany an application for an infill development permit. For any property where a Subdivision Design Grade Plan does not exist, it will be the responsibility of the applicant to work with an Alberta Land Surveyor to develop a Lot Grading Plan that illustrates both existing and proposed grades.
Grading for infill developments must be configured to move surface runoff to the abutting public sidewalk, road and rear lane. This can be achieved by developing an internal swale (located entirely within your property) or a shared swale (in cooperation with the adjacent property owner). Swales must be designed to provide a minimum slope of 1.5% for surface runoff.
The optimal goal is to handle drainage entirely within your property without negatively impacting adjacent lands. Developing common and internal property swales for infill developments is often the most cost effective and popular choice, as the water is handled within the property and directed toward the sidewalk, road, or lane.
Common property swales (Detail A) are possible where abutting properties are suitably graded (i.e. an existing approved infill development) or where abutting property owners collaborate to create typical property swale by undertaking grading improvements on both properties.
Internal swales (Detail B) are required for locations where a common property swale cannot be constructed due to unapproved grading on an abutting property.
Swale Details
When swales are included in the design, the lot grading plan must show their locations, slopes, and cross-section details.
Detail A Detail B
Properties Abutting Infill Development
For properties with no approved Lot Grading Plan, including properties abutting infill developments, it is highly recommended that all property owners establish and maintain surface grades and elevations adjacent to buildings so that the water drains 1) away from buildings and 2) toward a Town right-of-way (road, lane, sidewalk, etc.).
Regrading and Landscaping in Mature Neighborhoods
Regrading to alter the flow of surface runoff on premises must be illustrated in an approved Lot Grading Plan. Therefore, consulting with abutting property owners is critical when considering grade changes or downspout location changes affecting surface runoff management between neighbouring lots. Changes to a downspout or sump pump discharge location that directs surface runoff onto an abutting private property may be a bylaw violation.
Grading for Detached Garage/Buildings
The concrete pad for a detached garage or other building is elevated to provide a positive slope away from the building. Proposed grade elevations for pads are a design requirement and are presented on the Lot Grading Plan submitted with the Development Permit application.
The Lot Grading Plan must indicate how the water will be handled on the site, whether through a typical property swale, an internal swale or a retaining wall. The Town of Slave Lake does not require the Lot Grading Certificate to show proposed grades throughout the entire lot. However, proposed grades shall be shown around the detached garage/building and the side of the main building abutting the new structure.
Lot Grading Maintenance
Rain Barrels
Rain Barrels should have an overflow outlet that discharges water to a location past the excavation zone (approximately 4.5 m or 15 ft.). Watering plants and shrubs in this zone should be limited to the minimum amount required to sustain them.
Window Wells
Window wells are installed to accommodate foundation grading, ensuring a positive slope away from the home. Positive foundation drainage (draining away from the building foundation) is the most critical defence against water entering the basement. Ideally, water does not enter window well openings. However, water that does enter the window well should flow down the drain tile, installed at the time of construction, to the weeping tile system. Window wells should be free of debris or leaves to ensure water can enter the drain tile and flow to the weeping tile.
Eavestroughs and Downspouts
Stormwater collected by the eavestroughs is channelled to the ground through the downspouts. This results in a substantial concentration of flow at the discharge points. To protect your home and neighbours’ homes, downspout extension pipes should project past the excavation zone by approximately 1.2 meters. The excavation zone is typically 4.5 m (15 ft.) outside your foundation walls. Eavestroughs should be cleaned and inspected regularly to ensure unrestricted water movement with no overflow. Downspout extension pipes minimize foundation zone saturation, which increases the risk of water entering the basement (infiltration flooding) or frost heaving the sidewalks, driveways and decks. See diagram D.
Swales
Swales are shallow, sloped channels that move stormwater and underground water to a public right-of-way. Property line swales are typically shared by adjacent properties, providing surface drainage for both lots. See Diagram E. Internal swales may also be present on the lot and must be maintained. See Diagram F.
