SKUNK RIVER PIPELINE PROTECTION PROJECT NEAR DENMARK, IOWA SUB MAR.

SKUNK RIVER PIPELINE

PROTECTION PROJECT NEAR

DENMARK, IOWA

SUB MAR

Skunk RiverLee & Des Moines County, Iowa

ANR PipelineCompany

SUB MAR

Looking US at Bendway Weirs and stable bank, flat slope depositional areas are an excellent indicator of stability.

Before InstallationSkunk River

Lee & Des Moines County, IowaANR PipelineCompany

SUB MAR

Pre-project: Looking US from the area where the pipeline was exposed by river forces

Before InstallationSkunk River

Lee & Des Moines County, Iowa

Pre-Project: Looking US. The river was eroding the right descending bank, becoming over-widened, and eroding a top-bank farm levee. WE ARE GOING 1,000 FT OFF OF THE PIPELINE RIGHT-OF-WAY FOR A LONG-TERM SOLUTION.


ANR PipelineCompany

SUB MAR


Flow


ANR PipelineCompany

SUB MAR


2 Hard Points 9 Bendway Weirs LPSTP & ACM

Flow


ANR PipelineCompany

SUB MAR


LPSTP

Bendway Weirs, LPSTP & ACM

Flow


ANR PipelineCompany

SUB MAR


Looking DS at the ACM protection after the first flood, note erosion immediately US of the mats

Construction of Bendway Weirs, Hard

Points, & LPSTP occurred in October

2001SUB MAR

Well-graded stone, but few fines, for Skunk River project, Denmark, IA. To effectively use this stone we installed a

granular filter of 1 to 3 inch stone, then installed this stone.

Key trench for Bendway Weir #9. Granular filter (1 to 3 inch stone) is

installed, then overtopped with key stone.

Skunk River, Denmark, Iowa. Looking

upstream.

Keying into, and connecting the US

Bendway Weir with the DS Articulated Concrete

Mattress pipe cover protection using a section of Longitudinal Peaked Stone Toe Protection,

(LPSTP, about 1.5 tons/ft.)

Looking DS at the completed

LPSTP tie-in

Looking DS after 2 yrs, at ACM protection over a formerly exposed gas

pipeline

Note: Pipeline was exposed at the toe of both banks, meaning

the river had degraded (system-wide bed lowering) and

overwidened (CEM Type III).

A system of Bendway Weirs, seen here in a physical movable-bed

model, flow is left to right

UNREVETTED BEND REVETTED BEND

Newly installed Bendway Weir Effects of Bendway Weir

Within the weir

field 2.6 ft/sec

Thalweg 6.4 ft/sec

8.0 ft/sec

Looking DS at flow over a series of Bendway Weirs,

high water on Catt Creek & Savage Rd., NY 11/4/2004


ANR PipelineCompany

SUB MAR


Looking US at Bendway Weir #9 on the Skunk River, 8 more Bendway Weirs up-river plus 2 Hard Points US of that,

protecting 1,400 ft of bankline.

Looking US during high water, ACM mat placed to cover exposed sections of pipeline, flood has occurred since installation, weirs not in yet. Note eroded US bank.

Looking US. Sediment is being trapped by weirs. Banks are stabilized, vegetated (a good sign) with the

bank building (deposition, not retreating).

Looking US @ BW & stable bank. Note LPSTP in foreground


ANR PipelineCompany

SUB MAR


Skunk River, looking US from pipeline crossing, two years after installation

Skunk River – MatsLee & Des Moines County, Iowa

Submar Drawing No. AB643

2 Years After Installation1 Year After Installation

After Installation1 Year After InstallationBefore Installation

SUBMAR

ANR PipelineCompany

Looking DS at Bendway Weirs and ACM, Skunk River, Denmark, Iowa

Keys for Bendway

Weirs

Submar Mats

SUB MAR

ANR PipelineCompany

Bendway Weir

Post-project th

alweg location

Pre-project thalweg locatio

n

This last flood we had (July 2008) was pretty severe and flooded the fields on both sides of the river at the site.

After the water receded a few feet and the levee was visible again, it appeared to be undamaged. Also from what I

could see from the opposite side of the river (I couldn't get very close), the vegetation was undisturbed on the river side of the levee and there were no signs of erosion. The thalweg looked to be following the line of the ends of the weirs and the water close to the bank was moving very slow comparatively. And this was with a water level

several feet above the tops of the weirs (about five feet from the top of the levee)........nice!

Nick Beach, Construction Manager, SubmarSUB MAR

The End

Three pipelines are covered with ACM mats in the river, seen here at low water stage.Upstream of the right-of-way bendway weirs were installed in the bend. The water is just over the top of the weirs in this photo.

ANR PipelineCompany


Point Bar

Flow FlowFlow

Flow

Flo

w

Red

irec

ted

Flo

w

Uncontrolled Flow

Captured Flow

Bendway WeirsBendway weirs are a proven technology developed & used by the U. S. Army Corps of Engineers. Bendway weirs have been used in large rivers such as the Mississippi River & in small streams. Demonstration projects in small streams have found that in addition to stabilizing the outside of a bendway, weirs have provided improved fish habitat (quantity and diversity) to the stream.

Constructed Oct 2001

SKUNK RIVER PIPELINE PROTECTION PROJECT NEAR DENMARK, IOWA SUB MAR.

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