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1. What is a trap low?

Water accumulating on your street may be a result of a trap low

Some homes in Town are located near a trap low, an area in the street designed for surface storage during a rain event. For homes near trap lows, rainwater may accumulate on the road nearby, up to and sometimes including the driveway and a portion of the lawn. This is normal for areas with a trap low. The water should completely drain within 24 hours once the rain stops.

If water has accumulated on the road near your house, on your driveway or front lawn, you may be located near a trap low. If rainwater accumulation has not drained 24 hours after the rain stops, please contact Town of Cochrane Operations at 403-851-2590. (Information about the trap low may be on your property title.)

• Example of the water pattern on street with a trap low
• Trap low map

What is a trap low?

Trap lows are used in many neighbourhoods in Cochrane to slow the flow of water into stormwater facilities. We control the flow into stormwater facilities to reduce erosion and allow sediment to settle before the water flows into the Bow River. Alberta Environment requires the Town to control the flow of stormwater into the river to protect the overall environment.

In streets with trap lows instead of traditional storm drains, it may appear that the street is flooding. It is not. Trap lows are designed to hold the water on the street; properties on streets with trap lows are graded to keep the water from foundations.

Why the Town has trap lows

The Town began requiring trap lows instead of traditional storm drains in neighbourhoods built after 1998.

Because trap lows control the rate of release into the storm water system, it is easier to ensure the pipes will not become pressurized from upstream flows and cause potential issues downstream. If the flows are not controlled, downstream impacts could cause manhole covers to lift off, posing a serious safety concern. The stormwater facilities would also discharge the stormwater into the waterways at a rate that could cause erosion.

Is any action required?

In general, no action is required by homeowners who live near trap lows. If rainwater accumulation is not drained 24 hours after the rain stops, please contact Town of Cochrane Operations at 403-851-2590.

2. What is a swale?

Swales are concrete or grass channels used to catch and direct surface runoff.  If you have a swale on your property, it is your responsibility to ensure it remains clear and free of debris to allow water to drain freely.

Love your swale

Show your swale a little love and it will help water drain away from your home, your neighbours’ homes and all the way to the storm sewer:

• check your swales every week or two
• clear out snow, ice, leaves and other debris
• don’t direct downspouts into swales

If you have questions about the swale on your property, please contact us:
Email

3. Can I build a retaining wall on my property?

Yes, you may be able to, but please note:

• You must maintain the approved grading and drainage of the lot.
• You may not alter the grading of the lot in a manner that allows surface drainage onto a neighbouring property.
• You must maintain positive drainage away from the dwelling.

It is the responsibility of the property owner to ensure that the wall or structure is entirely located outside of any utility right-of-ways or easements that may be registered on the property.

If the retaining structure is greater than 1.2m high, an engineering design and building permit are required. A retaining wall that supports a structure or poses a risk to public safety follows the same requirements. Please note: the height of the structure is measured as the vertical distance between the ground levels on each side of the wall.

The design of the wall must be completed by a professional structural and/or geotechnical engineer and submitted with a building permit application to the Town of Cochrane for approval prior to the start of construction.

4. What is a lot grading certificate?

A lot grading certificate is confirmation that a building lot conforms to Town of Cochrane design grade specifications. 

Upon completion of house construction the home builder is required to grade the lot as per the approved building grade plan design grades (these grades would have been approved at the subdivision stage).

How to get a lot grading certificate:

• After the home is built and lot is graded, the home builder must engage a certified surveyor to survey the lot to verify that the grades match the design grades or are within the allowable tolerances (please refer to the surface drainage bylaw for acceptable tolerances)
• Once the survey is complete, the home builder submits an original copy of the Final Lot Grading certificate (signed and sealed by a Certified Land Surveyor or a Professional Engineer) certifying the grades are within tolerance. Generally, the builder also supplies a copy of the survey to the home owner around the same time.
• Once the lot grading certificate is received, the home owner may landscape their property
  Note: HOME OWNERS MAY NOT LANDSCAPE UNTIL A LOT GRADING CERTIFICATE IS RECEIVED
• Future changes to grades must conform to Town of Cochrane bylaws
• Property Line Grades cannot be altered under any circumstance

5. When is the Town responsible for infrastructure?

The developer of a new subdivision installs the infrastructure necessary to service the area: water mains, hydrants, sanitary and storm sewer infrastructure, roads, sidewalks, pathways, park areas, storm ponds, lift and booster stations, reservoirs, sound attenuation walls, drainage swales and so on. Once these have been installed, Town of Cochrane Civil Land Development signs a Construction Completion Certificate (CCC), accepting that they have been completed in accordance with the proposed design. A signed CCC is the beginning of a maintenance period where the developer is still responsible for any work or maintenance associated with the infrastructure. The maintenance period can be one to three years, depending on the utility. When the maintenance period expires, the Town performs a final inspection. If the infrastructure is in acceptable condition, a Final Acceptance Certificate (FAC) is issued to the developer, relieving the developer of all maintenance obligations. Once an FAC is issued, the Town accepts ownership.

6. Where can I get a Safety Codes permit application?

Visit Permits and Inspections for application forms and explanation of the process.