Brookfield Case Study


Problem:  The back yard remained so wet you could sink up to your ankles even during dry periods, making the yard virtually unusable.  A previous drainage system installed three years earlier did not solve the problem.  During heavy rains, water flowed from the surrounding properties into the back yard, creating flooding conditions.


Assessment:  The back yard is a sunken area terraced up toward the property lines.  Three surrounding lots, all 8 to 10 feet higher, drained toward the back yard. The yard itself is further recessed, creating ponding conditions.  An original drainage system collected only surface water, still leaving the ground very wet.


Solution:  The solution needed to address the flow of surface water toward the back yard as well as the flow of sub-surface ground water toward the back yard.  Ground water can frequently ooze out of the side of a hill or bubble up in a low area. The flow of ground water is affected by topography and soil type.  The solution involved two parts.  The first part was to construct a diversion structure on the upper level of the terrace, directing water into catch basins which connected into the lower system.  The diversion structure prevents water from flowing over the terrace walls and directs the water to the catch basins where it can be drained away.


The second part was to construct a network of French drains connecting to a central lateral which directed water out to the front of the yard.  The French drain collects the surface and sub-surface water that previously could not flow away.  Gravel in the French drain is left exposed to the surface, but soon becomes covered with grass to make it all but invisible.

Photo 1:  Sunken area remains soggy

Photo 2:  Soggy back yard terraced up toward property lines.  Upper properties drain toward this area.

Photo 3:  Sub-surface ground water exposed during trenching.

Photo 4:  Trenching for French draintile

Photo 5: Draintile and catch basins installed; shooting elevations to determine proper pitch.

Photo 6: French drain section

Photo 7: Finished French drain system before grass starts to grow.

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