|
GRAY AND OAK
DRIVE STORM CHANNEL
| PROJECT TYPE: |
Bio-Stabilization |
| CLIENT: |
Metropolitan
Sewer District |
| APPROX VALUE: |
$150,000 |
BIO-STABILIZATION:
Due to both ecological as well as engineering factors, concrete
reinforced flumes are seldom used for storm channel
reinforcement today. A very new trend is called Bio-Stabilization. Depending on the hydraulics
involved, it was discovered that simple concrete channels
actually increased the speed of water flow and made erosion
worse farther down the line. For this reason engineers
devised bio-stabilization - or the process where by natural
reinforcement methods (of which there are many) may be combined
with synthetic elements to create both a more stabile and
ecologically friendly storm channel. Over time nature
does the job of reinforcing the channel as the plants grow and
root themselves into the channel wall.
PROJECT SUMMARY:
At the intersection of Gray and Oak Drives
significant erosion was occurring at the bend in an MSD storm
channel due to severe runoff. All creeks in this area are
experiencing such failure due to continued residential
development.
PROJECT SOLUTION:
For this project three types of reinforcement were used.
The first was pre-cast channel liners which are
essentially blocks filled with dozens of holes which line the
channel and then are filled with soil. The second is a live crib wall, or essentially green logs stacked in an
interlocking Lincoln-log fashion with soil placed behind and
between to allow live stakes (young, green trees) to grown and
take root among them. The third method is a rock
revetment, or simply heavy stone boulders and rock placed
to help slow water flow.
To control erosion within the channel section,
Ideal work crews installed 2,362 Pavelock pavers, 115 linear
feet of crib wall, and over 5,000 live stake plantings.
Workers also installed 600 square yards of sod and several
dozen container plants to beautify and restore the bank areas
which abutted residential property.
As a testament to the strength of these natural reinforcements,
a severe storm shortly after completion did no structural damage. While some minor aesthetic plants and
sod were washed away, the bio-stabilization easily did its job
even very soon after construction.
SPECIAL CONSIDERATIONS:
Since the area was completely lined by residential
neighborhoods, special permits and easements needed to be
obtained. Additionally this meant there was difficult
access for crews and equipment. Finally, residential
property (yards, etc.) needed to be restored to original or
better condition upon completion.
PHOTOS:
|
Near project
completion, heavy rains soaked the site and filled the
creek. The heavy revetment can be seen lining the
channel along with the armor block. Restored sod is
in the foreground.
|
|
|
A close up of the
Armor Lock paver system.
|
Organized chaos as
excavation begins and the project gets underway.
|
|
|
The Lincoln Log type
structure is part of the live crib wall.
|
A nice shot of the
stone revetment along the channel.
|
|
|
A close up of "live
whips", of live pieces of tree which will eventually
begin growing on their own.
|
Another view of the
live whips and stone revetment.
|
|
|
A shot of the
continuing rains two days after the project wrapped up.
In the foreground the holes can be seen where large
container plants were placed but washed downstream.
|
|
|
