**A NEW SERIES OF SEDIMENT COLLECTORS FOR MONITORING TRUE BEDLOAD**

David A. Braatz^1^ and Randall L. Tucker^2^

^1^Aquatic Ecologist, Streamside Systems, Boonville, NC
dbraatz@streamsidesystems.com

^2^President, Streamside Systems LLC, Findlay, Ohio
rltucker@streamsidesystems.com

**Keywords**: fluvial sediment, monitoring, bedload, sediment sampling,
restoration

**ABSTRACT**

Streamside Systems LLC offers a bedload monitoring collector with
variable mesh screening to collect targeted sizes of bedload sediment.
Prototypes have been tested for continuous operation (3 to 5-month
periods) for sand to medium gravel moving as bedload. The Streamside
collectors sample true bedload, and avoid the collection of suspended
sediment and organic matter. Bedload net samplers such as the
Helley-Smith, which block a partial cross-section of the water column,
can become blocked by the inclusion of organic matter, and are biased by
including suspended sediments (from near the bottom of the stream, where
suspended sediment concentrations are highest). In low-gradient streams,
the Streamside collectors are pumped out, and can easily be back flushed
or "zeroed". A siphon removal system will work continuously with a
localized drop adequate to pull 20 to 25 gpm through the collector with
a 2-inch hose. The outlet hose allows samples to be collected safely
from the shoreline, even under high flow conditions, and for any desired
sample period (seconds to months).

**INTRODUCTION**

Sedimentation is generally identified as the leading water quality
problem in the United States. Streamside Systems LLC (Findlay, Ohio) was
formed to research, design, and market equipment to aid in the
prevention of sediment impacts to surface waters, and to restore
sediment-impacted aquatic habitats. One series of products was designed
to remove targeted sizes of sediments (generally sand and finer) as they
move downstream as bedload. These collectors are passive, noninvasive,
and scalable to any size stream or river. As a new, best available
technology (BAT) alternative to dredging, the collectors can **avoid**
the common adverse impacts of dredging, such as:

-   Habitat damage via unselective removal of gravel and cobble

-   Biological damage via removal of fish eggs, invertebrates, and
    organic matter

-   Resuspension of sediment-associated contaminants

-   Reduced water quality and increased turbidity due to substrate
    disruption, and

-   Morphological damage that can lead to headcutting

A wide variety of applications exist for this new type of passive
bedload sediment collector, including:

-   Habitat improvement for fish spawning or for endangered mussels,
    through selective removal of harmful fine sediments, an increase in
    the substrate median particle size (D50), and reduced embeddedness

-   Reduction in pond and reservoir sedimentation, by removal of bedload
    at the mouths of tributary streams

-   Solution to "hungry waters" below dams, by collecting the bedload in
    tributary streams, bypassing the reservoir, and reintroducing the
    sediment below the dam

-   Selective removal of a clean-washed commercial product (sand), with
    no increase in turbidity over ambient, while improving habitat

-   Reduction in water treatment costs for industrial, municipal, and
    agricultural water users

-   Prevention of downstream sediment impacts below dam-removal
    projects, below logging operations, and at stream crossings for
    roads and utilities

-   Maintenance of navigation channel depth in major rivers, and
    sediment bypass systems for coastal inlets

-   Supplying clean, sorted sand for beach nourishment programs

-   Restoration of aggrading channels or individual pools by installing
    collectors as grade control structures that remove excess sediments,
    and

-   Collecting bedload data to develop watershed sediment budgets; to
    develop sediment TMDL's; to measure nonpoint source sediment impacts
    throughout a watershed; and to collect bedload data to document
    damages, identify sources, and assess liability for sediment
    impacts.

**INSTALLATION AND OPERATION**

Bedload sampling is the specific application of Streamside collectors to
be addressed here. The portable collector is of stainless steel
construction and is dug into the streambed and anchored. As bedload
sediments move downstream over the collector, they drop through the
screen into a hopper and are continuously removed by siphon suction or
by pump-out. A computerized controller can be added to electric systems,
to pump on a timed cycle or with respect to stream stage or discharge.
Maximum particle sizes sampled depend on the width of screen slotting
used, the size of the collector, the hopper capacity, and the output
hose diameter. Prototype collectors that have been used for three to
five month periods of continuous operation had screen slots of 5mm, 0.5
inch, or 1.0 inch, with a two-inch outlet hose. Another Streamside
bedload sampler design uses three separate collection chambers, with
screening slots of 2mm, 8mm, and 64mm.

The collectors are scalable to any size stream, and multiple units
(e.g., 10-ton pre-cast concrete collectors, with large capacity urethane
hopper assemblies) can be linked together to completely cross major
rivers. The collectors can be constructed with or without sidewalls. For
small streams, a two-foot wide sidewall collector can use supplemental
wing walls to channel and collect 100% bedload (of the screen-selected
sizes) from a four to six-foot wide channel. Collectors without
sidewalls can be emplaced adjacent to each other, or small units can be
installed at various locations on a cross-section.

Streamside collectors measure the sediments that move along the stream
bottom and fall into the hopper. Leaf litter, invertebrates, eggs, and
other organic matter all pass over the collector unaffected. When a
collector without sidewalls is dug into the streambed, it is virtually
snag-free, and passively removes the targeted sediments on a continuous
basis. Sediment samples can be collected in a large bin or truck bed or
sediment basin while the equipment is unattended, and manual samples can
be safely taken over any time interval (from seconds to months) or any
hydrograph category (rising, falling, or flat). Small, portable
collectors can be used as bedload subsampling devices, or collectors can
be sized to target the entire stream width. Streamside Systems offers 10
and 20-ton pre-cast concrete collectors to commercial sand mining
operations, that can target 100% of bedload sand transport in large
rivers; this can offer invaluable data on continuous bedload transport
rates that have never before been available for major rivers. The
flexibility of allowing extremely long-term and large volume samples,
greatly reduces the variability and subsampling error inherent in
bedload sampling with alternative methods.

**DISCUSSION**

The numerous potential applications for Streamside Systems collectors
are mentioned in this paper because they define the various interest
groups that may fund and operate the sediment removal installations,
thereby providing bedload data on a wide range of stream types and
stream sizes, as a side benefit and at no cost to the "bedload
community". Adoption of Streamside Systems collectors as a Best
Available Technology (BAT) alternative to dredging for instream sand
mining operations, would give the aggregate industry a better product at
a lower cost, while eliminating significant environmental impacts and
positively improving instream habitat, and also providing some of the
best available bedload transport data for sand-bed streams. Many sites
hold the potential to "turn the pollutant into a commercial product",
while restoring sediment-impacted streams, and providing a funding
source for riparian restoration, for conservation easements, and for
monitoring programs. Clearly, cooperation and cofunding needs to be
encouraged among the community of "sediment stakeholders" in a
watershed.

Accuracy is a major issue yet to be addressed. We have conducted simple
measurements above and below Streamside collectors, with a Helley-Smith
sampler. Results showed that Streamside collectors were 94% efficient.
Since our collectors capture sediments that are moving along the stream
bottom (i.e., bedload) and drop into the hopper, and since the
Helley-Smith uses a net that sieves a cross-section of the water column
at the bottom of the stream (where suspended sediment concentrations are
highest), it is perhaps more logical to say that Streamside collectors
capture 100% of the "true bedload", and can be used to estimate the
degree of over sampling bias from water column nets that capture
suspended sediment plus bedload. We find it difficult to consider a net
clogged with loads of organic matter to be a "bedload sample". Perhaps a
new working definition of "bedload" is in order.

Streamside Systems collectors appear to hold great promise, particularly
for measuring sand and fine gravel transport. We have not yet built or
tested the collectors for coarse gravel or cobble, although they should
be scalable to any desired particle sizes. Several studies are currently
underway regarding trout habitat improvement, morphological impacts, and
macroinvertebrate recolonization studies, but much research remains to
be done.