HomeMy WebLinkAboutMiscr -
From: Bonnie Waltonql�a�&Suzy .
Sent: Monday, February 06, 2012 5:48 PM I,
To: 'w.watters'
Subject: RE: LUA-11-065 Appeal
Dear Mr. Watters:
Thank you for your email correspondence related to the May Creek Drainage Improvement Project Permit & Variance
appeal. This will be made a part of the record and forwarded to Councilmembers and appropriate staff for their
consideration as the process moves forward.
Sincerely,
Bonnie I. Walton
City Clerk
City of Renton
425-430-6502
From: w.watters mailto:w.watters comcast.net
Sent: Monday, February 06, 2012 4:42 PM
To: Bonnie Walton
Subject: RE: LUA-11-065 Appeal
To: Ms. Bonnie Walton
Renton City Clerk -
RE: LUA-11-065 Appeal of Hearing Examiner's decision
It appears that King County is still pursuing the dredging of May Creek without properly addressing
the issues brought up by Dr. Patricia Olson, Ecology's Senior Hydrogeologist and others.
The State Dept of Ecology denied the necessary permits for this project due to flaws in the studies. King
County WLRD has failed to prove that there will be no adverse impacts downstream.
This fact is documented in the Hearing Examiner's findings and the DOE letters dated 9-1-2011 and 9-22-2011
entered into the record.
Until King County provides additional baseline data and appropriate erosion and flooding studies, they have
nothing new to argue that could reverse the department of Ecology or the City of Renton variance -permit
denial.
I am concerned about potential adverse impacts that this project may cause to May Creek's habitat, its wetlands
and downstream properties. Unless the proper studies are done, these impacts could easily exceed the potential
benefits that are expected.
Please deny the project's permits at this time.
Sincerely,
Wayde Watters
11608 SE 286th Street
Auburn, WA 98092
l?� /
-a3-�1
From: Bonnie Walton
Sent: Monday, February 06, 2012 8:26 AM
To: 'Julie P. Bonwell'
Subject: RE: Comments to KC Appeal of Renton's Hearing Examiner's Decision
Dear Mr. & Mrs. Bonwell:
Thank you for your email correspondence related to the May Creek Drainage Improvement Project Permit & Variance
appeal. This will be forwarded to Councilmembers and appropriate staff for their consideration as the process moves
forward.
Sincerely,
Bonnie I. Walton
City Clerk
City of Renton
425-430-6502
From: Julie P. Bonwell jmailto:jbonwell@lesourd.com1
Sent: Sunday, February 05, 2012 7:54 PM
To: Bonnie Walton
Subject: Comments to KC Appeal of Renton's Hearing Examiner's Decision
City of Renton
c/o Ms. Bonnie 1. Walton
City Clerk
bwalton(&._r_entonwa.gov
Re: Comments to King County Appeal of Renton's Hearing Examiner's Decision
Councilmembers:
Significant concerns raised by citizens (erosion, flooding), the Washington State Department of Ecology, and others
regarding the proposed project (May Creek) have not been addressed.
Dr. Olson and others in the Department of Ecology believe the county's proposal includes inaccurate data, bad analysis
and bad conclusions.
Dr. Olson, other Ecology personnel, and the Muckleshoot Department of Fisheries visited the sites at least twice. My
husband was home on one of those visits. Has the City of Renton come to see for themselves the erosion we already
have downstream (in our reach)?
The Department of Ecology is asking the county to respond to their comments and questions. They are
requesting a bank erosion model. Our home and bridge are located on the banks of May Creek. The Hearing Examiner
recommends that a third party review the additional data and studies required by Ecology.
The county's assertion that there will not be downstream impacts cannot be supported by studies based on inaccurate or
incomplete data. The potential exists for negative downstream impacts per the scientific review of this proposal. Why is
the City of Renton allowing King County to push their problem on the City of Renton and/or its citizens?? When experts
(and lay people living creekside) challenge the county's study, it is loud and clear - those discrepancies must be
addressed before going forward with any sediment removal from May Creek. The issues must not be ignored. Our
homes and bridges are at stake.
We respectfully request as citizens of Renton, the Renton Council deny the appeal of the permit and variance the county
is seeking from the City. Thank you.
Jim and Julie Bonwell
2914 Lyons Avenue Northeast
Renton, Washington 98059
z
From: Bonnie Walton
Sent: Monday, February 06, 2012 8:15 AM
To: 'Debra Rogers'
Subject: RE: May Creek appeal
Dear Ms. Rogers:
Thank you for your email correspondence related to the May Creek Drainage Improvement Project Permit & Variance
appeal. This will be forwarded to Councilmembers and appropriate staff for their consideration as the process moves
forward.
Sincerely,
Bonnie 1. Walton
City Clerk
City of Renton
425-430-6502
From: Debra Rogers Lmailto:herogers@wmcast,netl
Sent: Saturday, February 04, 2012 10:51 PM
To: Bonnie Walton
Subject: May Creek appeal
To: Ms. Bonnie I. Walton
Renton City Clerk
bwalton@rentonwa9ov
RE: LUA-11-065 Appeal of Hearing Examiner's decision to full Renton City Council
*As a point of information ... I am a party of record for the hearing held by the hearing examiner.. -though I did not get
notice from the City of Renton.
I am writting regarding King County's request to dredge part of May Creek and alter the wetland which is on property
that is owned by the neighborhood I live in, Stonegate.
I attended the initial King County meeting held in ]an 2010 and I have continued to follow the process that King County
has taken in their attempts to get permission to dredge May Creek.
I know that the City of Renton has denied the King County's dredge plan twice and that the Department of Ecology (DOE)
has also denied the King County plan. I also appreciate concerns that other agencies have stated of this project., I
especially appreciate and respect the input that Doctor Olson, Senior Hydrology Specialist with the Department of Ecology
(DOE) has given.
I have voiced and submitted concerns since May of 2010 of my personal objections which are; I feel that the paperwork
and reports that King County has submitted to substantiate the impact of their plan does not adequately cover the
concerns that I have for clownsteam erosion and/or flooding, or the effects on the wetland itself, and changes that
dredging and mitigation will have on the character of the stream, and the impact these changes will have on the fish and
wildlife that live in and off of the creek.
I also remain extremely frustrated that the objections of concern by the Department of Ecology and other agencies
continue to be ignored by King County though these agencies restate and restate these concerns to King County over and
over again.
I urge the City of Renton to deny permits to King County for this May Creek Dredge project until ALL denial concerns of
the City of Renton and the Department of Ecology and other agencies are ALL addressed with valid certifiable data and
not allow King County to continue to side step these important issues in attempts to dredge May Creek.
Respectfully,
Debra Rogers
5326 NE 22nd Court
Renton, WA 98059
�uzzu-
/-
From: Bonnie Walton
Sent: Monday, February 06, 2012 11:25 AM
To: 'A. Duffus'
Subject: RE: LUA-11-065, V -H, SP Appeal of Hearing Examiners decision dated January 9th, 2012
regarding May Creek Drainage Improvement Project
Dear Mr. Duffus:
Thank you for your email correspondence related to the May Creek Drainage Improvement Project Permit & Variance
appeal. This will be forwarded to Councilmembers and appropriate staff for their consideration as the process moves
forward, and will be made a part of the record.
Sincerely,
Bonnie I. Walton
City Clerk
City of Renton
425-430-6502
From: A. Duffus[maiIto: blueheron6%RZ@hotmail.coml
Sent: Monday, February 06, 2012 11:09 AM
To: Bonnie Walton
Subject: LUA-11-065, V -H, SP Appeal of Hearing Examiner's decision dated January 9th, 2012 regarding May Creek
Drainage Improvement Project
Dear Ms. Walton:
Please find attached my comment letter and exhibits regarding King County Water & Land Resources
Division's appeal to City Council.
The three exhibits attached are:
✓ Agenda of a meeting between King County and Washington State Department of Ecology, October 181h,
2011
✓ A handout from that meeting entitled: "HEC RAS Sediment Transport Model "
✓ Three e-mails exchanges between King County and Ecology dated December 20" & 21512011 and
January 6`n, 2012
Thank you,
Andrew Duffus 425-255-9405
9605 143`d Avenue'SE
Renton, WA 98059-3764
February 5h, 2012
Councilmembers
City of Renton
Renton City Hall
1055 South Grady Way
Renton, WA 98057
VIA: E-mail to Ms. Bonnie 1. Walton, City Clerk
RE: LUA-11-065 V -HSP Appeal ofHearinQ Examiner's decision dated January 9th, 1012
regarding May Creek Drainage Improvement Proiect
Dear Councilmembers:
Attached to this letter is new evidence. This evidence could not reasonably have been available at the
time of the hearing before the Examiner, (October 4`h, 201 l) because Washington State Department of
Ecology had not prepared nor presented it to King County Water & Land Resources Division. The new
evidence is the Agenda and attached handout for an October 18'", 2011 meeting between the State
Department of Ecology and King County. The handout is entitled "HEC RAS sediment transport
model."
Under the handout's subheading, "No discussion on a number of important factors" are fourteen (14)
questions from State Ecology questioning King County's modeling methods, assumptions and
conclusions. The handout states, "So you have model error compounded on model error plus an
unknown error associated with the sediment data collections. Not a high level of confidence."
(Emphasis added.)
Under the subheading, "Anchor sediment study" are four (4) more questions. In addition, statements in
the handout reflect the lack of validity of the modeling and its conclusions, to wit:
➢ "This analysis illustrates that 1 (one) measurement for a long reach is not adequate to
evaluate site specific incipient bedload transport which is one piece of information
needed for a hazard assessment." (Emphasis added.)
➢ "But more importantly critical shear stress and incipient bedload transport calculation is
just one factor in erosion and channel movement." (Emphasis added.)
➢ "Bedload transport is known to be highly unpredictable." (Emphasis added.)
➢ "...sediment transport ... (is) ... influenced ... by magnitude ... and duration,... duration
is an important factor to sediment transport and bank erosion."
The Ecology handout notes the inadequacy of County's analysis of possible adverse downstream
impacts from erosion (sediment transport) to both streambed and stream banks. The handout states,
"The data provided by King County does not address any of these." (Emphasis added.)
The handout concludes that there are three possible options. The two most important to us,
downstream citizen -property owners are:
"Collect additional data in reach of contention and add a bank erosion model' (emphasis
added)
• "Compensate for flood storage by adding equivalent or greater storage."
Therefore, this new evidence, (hereto unavailable) is further proof that County has not satisfied the
City of Renton's Hearing Examiner's earlier finding that "There is insufficient evidence to establish
that the drainage project will not adversely affect downstream properties by increasing erosion."
(Final Decision, November Sth, 2011, page 1, line 17,)
Nor has County satisfied the Washington Department of Ecology earlier denial of the Section 401
Water Quality Certification for the May Creek Drainage Improvement Project. Ecology stated, "...we
have not received all of the documentation needed in order to demonstrate that we have reasonable
assurance that the state water quality standards will be met." (Ecology letter September 22"d, 2011)
Note, the County first applied to Ecology and United States Army Corps of Engineers for federal and
state water quality certification in early 2010. On January 26th, 2010, King County held an interagency
meeting with Ecology, the Corps, the Muckleshoot Indian Tribe and others. Yet, to -date, over two
years later, the County has been unable to satisfy the requirements of Sections 401 & 404 of the United
States Clean Water Act.
For this project to proceed King County needs a Critical Areas Ordinance Variance and Special
Grade/Fill Permit from the City of Renton. County needs these is so it can create "mitigation" in the
relatively undisturbed 3.75 -acre wetland. (Stonegate tract "A") This mitigation is to counter the
adverse impacts of dredging May Creek upstream.
The reason for the dredging is to allow stormwater to drain more frequently and quickly from the
grazed wetland horse pastures located in the upstream natural floodplain. This proposed project will
release the stormwater more quickly and at a higher volume than the current rates. The concern is that
this will exacerbate the flooding and erosion downstream, thereby impacting riparian habitat, citizens'
homes and private bridges
King County has not demonstrated that the project will not have an adverse impacts downstream.
The contention is homes and sole access private bridges and riparian habitat are at risk if the applicant
dredges upstream. The goal of the upstream dredging is to alleviate some of the seasonal storm water
ponding in the wetland -floodplain. The purpose is to facilitate addition pasture grazing for horses. It
could be said, this is an issue of "homes versus Horses"!
Reviewing King County's appeal, I have the following questions, comments and observations:
The County says this is a small project. It is not a small project if has unintended consequences that
adversely impact downstream. For a relatively short period of the year upstream residents experience
temporary seasonal loss of their horse pastures. Every year, downstream residents experience flooding
and erosion. Erosion steals our property forever, not just seasonally! We lose are property
nermanently,,,t. hardly comparable to the relatively minor inconvenience of temporary seasonal
wetness in the horse pastures.
The appellant's reference to May Creek and its associated wetlands as a "drain pipe" is a gross insult to
this 10,000 -year-old watershed! The County notes, "Valley residents depend on this drain pipe..."
Well, we down streamers also depend on this "drain pipe" (a.k.a. 10,000 year old wetland) to do what
wetlands are supposed to do. That is, meter out the storm water inundation so that downstream
flooding and erosion impacts are not as otherwise severe.
However, to parallel the County's despicable "drain pipe" analogy, what happens when you clear a
clogged kitchen drain? The volume increases and flows down the kitchen drain faster. This is why we
down streamers are concerned, more storm water flowing faster instead of metering out of nature's
retention—detention pond, the wetland. The appellant claims that it is not effectively enlarging the
"drain pipe". Excuse me; the proposal is to increase the stream channel capacity from 6 cubic feet per
second to 50. If that is not an enlargement, what is?
The County's appeal states, "Valley residents are no longer allowed by regulations to clean their
obstructed "drain pipe," that is May Creek. Well neither are we downstream residents allowed to
armor our eroding banks, build berms to alleviate flooding of our homes, or reinforce our sole access
bridges. (See Renton City Code Enforcement records regarding the Lyons Avenue NE private bridge,
the sole access to four properties.)
The County states, "They (upstream residents) are no longer able to restore the lost use of their land
caused by sedimentation...." Neither can we downstreamers restore the use of our eroded land as it
has washed downstream to Lake Washington. Lost forever!!
The appellant claims it has analyzed the proposed project extensively. However, the State of
Washington Department of Ecology's senior Hydrogeologist, Dr. Patricia Olson, after field visits and
review of said analysis, challenges the County's conclusions. The County lists 12 reports that it
contends, "show there are no adverse downstream impacts". The problem is only TWO (2) of'these
re oris s ec scall address downstream erosion. None addresses flooding. (See note below
regarding May Creek Basin Action Plan.)
One of the 12 reports, the "May Creek Erosion Stabilization, Draft Report" describes 24 projects
proposed to stabilize the downstream banks, protect riparian habitat, peoples' homes and sole access
private bridges. The Erosion Stabilization report not only acknowledges the fact that there is sever
erosion and flooding downstream, it recommends 24 projects to address this fact, including, but not
limited to, buying out -at -risk properties, rebuilding bridges or developing alternative ingress and egress
to the peoples' properties or realigning the May Creek channel. The report contains phrases such as
"risk to life and property". Hardly supportive of the County's upstream "drain pipe" clearing proposal
if there is exacerbation of the documented erosion and flooding downstream!
The appeal states that, Dr. Patricia Olson "has concurred in a separate meeting that our fluvial
geomorphologist has applied more superior formulas than exist in the HEC -RAS model." If that is the
case, why are the questions contained in the handout entitled "HEC RAS sediment transport model."
still outstanding? Why is the County, as of January 2012 "...still working a package specifically for
Ecology..." (E-mail attached)
The appellant states that it is not the County's position that the erosion threshold is at the lower end of
the range of 73 to 230 cfs. However, in the October 4t', 2011 City of Renton Public Hearing, Don
Althauser, Managing Engineer of King County W&LRD testified that the threshold of erosion, quote,
"ranges between 75 to 200 cfs and we will continue to sample what is real."
The County states that there are unique substrate conditions in the Duff-us/Coates reach. Unique or
otherwise, that is no reason to blow off the fact that the proposed channel -clearing project may
exacerbate an already serious erosion problem. Especially given that Coates' house is poised upon this
very bank of the creek and may well be in danger. If this unique substrate has a lower threshold of
erosion that needs to be determined and mitigation implemented.
The Hearing Examiner contends the County relied on flawed data. Well, it did. How else to explain
the Ecology's questions at the October 180, 2011 meeting. Further, why is County still attempting to
address those concerns and the concerns expressed in Dr. Olson's memo of August 15`h, 2011? (See e-
mails between Ecology and County dated December 20'x' & 21St, 2011 and January 6th, 2012, attached.)
As to the City of Renton staff review, it was a routine desk review of the appellant's application. City
staff did no field visits nor onsite analysis. Staff did not evaluate downstream erosion and flooding.
The city staff "Preliminary Report to the Hearing Examiner" gave bare mention of the fact that the
State Department of Ecology had denied King County necessary certification to proceed with the
project. There was one reference to the Ecology's decision to deny certification, almost a footnote. A
copy of Ecology's denial was not even included as a numbered exhibit in the preliminary report. City
staff not only over looked certain facts but also allowed a gap in relevant information. It rested upon
the concerned public to highlight this major omission.
County infers that various adjacent landowners, in part, caused downstream problems. Has King
County factored in the decades of illegal filling and grading and channel realignment in the upper
reaches of May Valley? Some of this by the very upstream proponents of this ill-conceived dredging
proposal. To verify those historic illegal "modifications" see King County Department of
Development and Environmental Services website for the various creek -side properties citations.
These historic "modifications" not only impacted the property of fellow unstreamers by forcing storm
water flooding from one side of the valley to the other, but the filling and grading sent stormwater
more quickly downstream, thereby impacting our homes and bridges.
For some real entertainment, read about the self -described "vigilante" who in the heat -the -night drove
his track -hoe into May Creek and illegally dredged the stream. (Various local newspapers, August
2001)
On the one hand, the appellant argues that there is no evidence that Dr. Patricia Olson memo is the
official position of Ecology. But on the other hand, County recently e-mailed Ecology, "...we are still
working a package specifically for Ecology..." (E-mail attached)
The Hearing Examiner states, "...it is not possible to conclude with any reasonable degree of
confidence that downstream properties will not be adversely affected by the project." (Decision on
Reconsideration, January 9h, 2012, page 2, line 21,)
As a downstream resident, the adverse impact nightmares that I have in my sleep are:
0 What will King County do if the creeks banks blow out?
■ What will County do if Roger Coates' house tumbles into the creek, the Madfai's, or Gary
Cole's or the Bonwell's houses are flooded?
■ What will County do if our private potable wells are adversely impacted?
■ What will County do for us if our private bridges collapse? (Note there are eight properties that
rely on these private bridges for access. The County infers, in its appeal, that it is only the
Duffus/Rollins bridge.)
If any of these adverse impacts should occur:
■ What are County's contingency plans?
■ What is the County's budget to rectify?
■ How soon will we, if aggrieved, be made whole?
May Valley Wetland #5 at 208 acres, is one of the largest freshwater wetlands in King County. The
3.75 -acres within Renton City Limits that the appellant wants to modify are a relatively undisturbed
portion. (Stonegate tract "A") In 2008, King County contracted with Mid -Puget Sound Fisheries
Enhancement Group to remove Reed canary grass from 15 feet on either side of the creek in the
Stonegate wetland. It does not need to be restored a second time. The only reason for disturbing and
altering this wetland again, is as mitigation for the proposal to dredge upstream in an ill-conceived
effort to drain horse pastures.
The issue boils down to assessing the possibility of adverse impacts downstream. The Renton Hearing
Examiner has denied the necessary permit and variance twice, as has Washington State Department of
Ecology. Like Ecology, the Hearing Examiner found no proof that there will be not be downstream
impacts. The question then, as now remains, has King County addressed all the concerns? The answer
is no!
Therefore, I respectively ask Renton City Council to support the Examiner's decision to deny the
Critical Areas Ordinance Variance and Special Grade/Fill Permit.
Thank you.
Sincerely,
Andrew Duff -us
The "May Creek Basin Action Plan" addresses in broad terms overall flooding and erosion in May
Creek Basin. The plan is not specific to possible significant adverse impacts downstream of the
proposed dredging project.
Exhibits: three
✓ Agenda of a meeting between King County and Washington State Department of Ecology,
October 18`h, 2011
✓ Handout from October 18`', 2011 meeting entitled: "HEC RAS Sediment Transport Madel "
✓ Three e-mails exchanges between King County and Ecology dated December 20" & 21s'2011
and January 6`h, 2012
• Transport equation used in HEC RAS model? Results compared from all appropriate
equations? Lateral boundaries? Upstream boundary?
• HEC RAS requires that upstream sediment loads are specified 'or they can be calculated
by the model. Which was done? How do know them if sediment sources and quantities
are not determined? What are they based on?
• Sediment transport results are strongly dependent on which transport function is
selected and energy slope: Was the default based on Manning's n used or the actual
slope of the energy grade line?
• Did you overwrite the mobility coefficient (varies as to equation used in MPM it is
critical shear stress, Ackers is threshold mobility, Wilcock is reference shear stress)
with specified variables.based on reference data or data representative of this reach? If
so how determined? Theoretical or empirical?
• DEC RAS manual emphasizes that transport coefficients represent the central tendencies of
the data considered but will not likely reflect the transport of a specific site precisely even if
an appropriate transport function is selected. There can be substantial error in sediment
transport
• HEC RAS requires that upstream sediment loads are specified ore they can be calculated
by the model. Which was done? How do know them if sediment sources and quantities
are not determined? What are they based on?.
• No discussion of error: The conclusion of the HEC RAS model is partial and tentative,
because real rivers are not 1D and numerical models are less than perfect expressions
of reality. Then you tie that with inadequate sediment data to conduct a hazard related
erosion analysis. and there you go. Also you have error from HSPF, HEC RAS hydraulic,
HEC RAS sediment and very limited sediment data So you have model error_
compounded on model error plus an unknown error associated with the sediment data
collection. Not a high level of confidence.
Anchor sediment study
• Data collection and monitoring was focused on three stations (cross-sections of the
creek) located throughout the project reach at approximately RMs 2.9, 3.4 and 3.6. All
sites are downstream of the properties in the upper ravine. What were the criteria used
to determine these locations? What was the sampling design? No discussion of
sampling error based on techniques.
• Station 3 is the more representative but does not provide adequate data to evaluate
erosion on a site specific basis. Nevertheless, significantly more bank recession and
channel movement occurred at this site than the other 2. We observed that the reach
was actively migrating with bank erosion.
• The incipient motion calculation was interpolated between 70 cfs and 350 cfs using a
simple linear relationship. Not appropriated because it is not a linear relationship as
shown by the transport equations.
The uncertainty with the data was expressed in the study summary:
"It is important to note that there is a fair amount of uncertainty with this value.
To illustrate some problems with limited data, looked at potential to initiate bedload,
transport bydetermining critical shear stress for 3 additional empirical critical shear stress
equations and then used to compare HEC RAS profile data, at different flows..
Channel shear: lb ft -2 from Anchor study
Shields Relation
Shields Relation .
Ashworth and Ferguson (1989)
dell
d50
d70
d10
d50
d70
Station 1 0.8
1.0
1.9
1.0
1.8
2.4
Station 2 0.5
0.5
0.7
0.6
0.9
1.1
Station 3 1 0.5
0.4
0.6
1 0.6
0.8
0.9
Convert channel shear in lb ft -2 to Channel shear in N m -z
N nix
Shields Relation .
Ashworth and Ferguson (1989)
Station
dell d50
d70
d10
d50
d70
1
38.304 47.88
90.972
47.88
86.184
114.912
2
23.94 23.94
33.516
28.728
43.092
52.668
3
23.94 1 19.152
28.728
28.728 1
38.304
43.092
3 additional shear stress estimates
Hydraulic Radius and Total Shear Stress for High Flow Events (Modeled) from Anchor study
Return
Shields (0.056)
Parker 1990
Miller 1977
d50
d70
d50
d70
(ISO
d70
Station 3
25.4
38.1
34.8
36.2
20.4
30.1
Hydraulic Radius and Total Shear Stress for High Flow Events (Modeled) from Anchor study
Return
Flow in
Period
Creek (cfs)
Rh (ft)
Ts (lb/ft2)
N m z
� range for D� at site 3, 20.4-38.4 N
rn" N=S, Potential for initiation
(years)
Mean i13.6
Annual
0.4
0.7
33.516
Yes within range
2
208
1.2
1.9
90.972
Yes
5
243.
1.4
2.1
100.548
Yes
10
347
1.7 •
2.6
124.488
Yes
20
429
1.9
2.8
134.064
Yes
t
Cross-section specific BEC -RAS model (from Anchor study)
Profile Channel stress [b ft"= Channel stress N to
While one reach with obvious bank erosion appears to have similar sediment size
distribution to Anchor site 3 (Photo 1 and 2), there are substantial variations among
profiles. This analysis illustrates that 1 measurement for a long reach is not adequate to
evaluate site specific incipient bedload transport which is one piece of information needed
for a hazard assessment.
The above simple analysis illustrates the limitations of the 3 point data in evaluating
specific sites. But more importantly, critical shear stress and incipient bedload
transport calculation is just one factor -in erosion and channel movement
Temporal and spatial influence on sediment transport indicate that increased flow
event durations such as 7 extra hours per year for a 100 cfs storm 6 hours per year
for a 75 cfs storm could be very significant should additional sources of sediment
from armor break up, bed mobilization and bank erosion be added.
• Bedload transport is known to be highly unpredictable. One reason is time varying
passage of upstream sediment causes fluctuations in rate.
o The supply of sediment available to be transported is known to be a function of
both temporal and spatial variations in entrainment characteristics (cluster,
D50 at 24.4-38.4 N m'2 N=5
M, 2
Potential for initiation
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i
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_ -M _
;}
2440
0.07
3.3516
No
1964
0.34
16.2792
No
a -x c -`. '�
__
«:tS.� i#a�Q4.'_*
- .y:S..S
.1`_,= r '_5 +� r r
...y. .",. . 'R:
a
-- =' .-. W- ;;•sI::�T'.::s:.^-..�.'Y
.
rte? M.L:!= �= is ::i�?ii}:-
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: R:' .1.1 _[S'�L
i:L_.-rr<�_ ate__,_.._._..,,'s;;.-s,:r^s':«TS:.�:�J-�Si.-.M.:a....'
Reach average
0.55w
26.3
Yes, within range
While one reach with obvious bank erosion appears to have similar sediment size
distribution to Anchor site 3 (Photo 1 and 2), there are substantial variations among
profiles. This analysis illustrates that 1 measurement for a long reach is not adequate to
evaluate site specific incipient bedload transport which is one piece of information needed
for a hazard assessment.
The above simple analysis illustrates the limitations of the 3 point data in evaluating
specific sites. But more importantly, critical shear stress and incipient bedload
transport calculation is just one factor -in erosion and channel movement
Temporal and spatial influence on sediment transport indicate that increased flow
event durations such as 7 extra hours per year for a 100 cfs storm 6 hours per year
for a 75 cfs storm could be very significant should additional sources of sediment
from armor break up, bed mobilization and bank erosion be added.
• Bedload transport is known to be highly unpredictable. One reason is time varying
passage of upstream sediment causes fluctuations in rate.
o The supply of sediment available to be transported is known to be a function of
both temporal and spatial variations in entrainment characteristics (cluster,
armoring and patches) of the channel bed. In supply limited rivers (as May Creek
ravine reach was described), the sudden availability of new sources of bedload
from armor break-up, bar mobilization or bank collapse, may become locally
important. Such variability is reflected in the high degree of scatter recorded in
bedload transport datasets, although it seems particularly pronounced in supply
limited humid -temperate streams.
Sediment heterogeneity increases variation in bedload transport in time and space
within one flow event.
0 1-D models, such as HEC RAS, results represent instantaneous, rather than time -
averaged, critical shear stresses.
o Equal mobility influences sediment transport in armored beds.
■ This mechanism is most often observed in reaches with'a coarse armor
layer in which coarse particles are exposed to the surface that provides
them with an increased chance of transport Fine particles are hidden
below the surface where their transport probability is diminished. Thus,
the preferential exposure of larger particles in the armor layer acts to
equalize the mobility of coarse and fine particles and eliminates most of
the differences in the mobility of small and large particle sizes. Once the
small particle sizes are mobilized they increase entrainment and
transport of larger particles.
An important element in the process of bedlaad transport is the extent to which local
vs. remote sources of supply interact with the sequence of flows to create temporal and
spatial variability in transport at a section.
o As water levels rise additional sediment sources (armor break up, bars, banks)
and recedes (banks) become available. But they also establish connectivity between
sediment sources over much longer reaches of channel.
o The duration of flow over the critical threshold for transport and where the
sediment sources are within the upstream reach strongly influences interaction
with sources and connectivity along a reach.
Given the above sediment transport characteristics as influenced not only by magnitude
of event but also duration, duration is an important factor to sediment transport and
bank erosion. The data provided by King County does not address any of these.
Banks may erode even if bedload does not move especially where basal erosion is
already occurring (Photo 2). Where is the bank erosion model?
• Sediment transport occurs in the longitudinal direction AND transverse directions.
Both affect bank erosion. HEC RAS cannot predict in transverse direction nor can it
model for channel migration -
• Bank erosion consists of two interactive physical processes: basal erosion and bank
failure. Basal erosion (Photo 2, 3) refers to the fluvial entrainment of bank material (in
this case consisting of smaller sediment size) by flow -induced forces that act on the
bank surface.. Bank failure occurs due to geotechnical instability (e.g. planar failure,
rotational failure, sapping or piping).
The rate of bank erosion traditionally is calculated empirically from the geometry of
channel fiends, bank material, and flow intensity. Bank failure can occur before bedload .
transport is initiated.
These modes of failure have distinct characteristics, and an investigation must be
conducted to.determine the specific mode of failure because this is often indicative of
the underlying problem at a site or in a reach or system of time, and 2] to monitor
changes at specific points by repetitive surveys or through the installation of bank pins.
The first approach offers the benefit of providing immediate results for average
bankline retreat, while the second method provides insight into event- specific bank
loss..Because erosion tends to be episodic, periods of 10 years or greater are
recommended for aerial photograph time -series analysis as well as bank pin
monitoring. .
grating
Banks also erode during bedload movement es
streams.
in meandering balance of sediment lload
streams. Whether a bank retreats or advances depends
at near -bank regions where sediment may come from upstream, bank erosion, and
secondary flow. The strength of secondary flow in redirecting bedload transport
correlates with the local radius of curvature as well as sinuosity of meandering
channels. Flow momentum redistribution causes bed degradation near concave banks
and deposition near convex banks. Bed degradation steepens concave banks and
deposition stabilizes convex banks. This causes concave banks to retreat as flank
erosion occurs, while convex banks a6ance with the build-up of point bars. This
process occurs within the reach between Lyons and 143rd Street Bridge.
3 poisible. options:
• Collect additional data in reach of contention,and add a bank. erosion model. F.._
• Compensate for flood storage by adding equivalent or greater. storage :: ; ::.:.`: •. :;;_,
• York with landowners, not just a meeting or.two, to developa:solution that is amenable'
From: Miller, Lindsey(mailto:Lindsey.Miller@kingcounty.gov]
Sent: Friday, January 06, 2012 7:52 AM
To: Padgett, Rebekah (ECY)
Cc: McGraner, Patrick (ECY); Jason Mirro; Stockdale, Erik (ECY); Olson, Patricia (ECY); Chin, Doug; Joshua
Monaghan
Subject: RE: May Creek Water Quality Samples
Rebekah — Below is a link to the package that we submitted to the City of Renton for this project. It contains
some of the information that you need, but not all. We are still working a package specifically for Ecology that
will contain all the information we submitted to the City plus more. When Doug and I looked at the schedule
earlier this week, we determined it would probably take us another two weeks to finish getting this package
together for you.
http://vour.kingcounty.gov/kcdot/roads/transfer/imillerlMayCreek-RentonReconsiderationPackage.zip
Also, please let me know when you have downloaded the City of Renton package so that we can take it off our
server. This is only a temporary location.
Thanks,
Lindsey
From: Miller, Lindsey
Sent: Wednesday, December 21, 20119:51 AM
To: 'Padgett, Rebekah (ECY)'; Chin, Doug; Joshua Monaghan
Cc: McGraner, Patrick (ECY); Jason Mirro; Stockdale, Erik (ECY); Olson, Patricia (ECY)
Subject: RE: May Creek Water Quality Samples
Hi Rebekah — Doug is out of the office over the holidays but I just wanted to reply and give you a quick update.
We have been focused on preparing a submittal package for the City of Renton Hearing Reconsideration and
that package is being submitted to the City today. The City of Renton package contains a lot of the same
documentation needed to address Ecology's comments (including documentation on Long Marsh Creek
footbridge backwater affect), but we still have a few more items that we are trying to get together before we
send our official response to Ecology.
We have also been working with Jay Mirro on ideas for how to incorporate implementation of the agricultural
BMPs into this project. We have reached out to DDES for their help on this component of the project, but have
not received any feedback from them yet.
We visited the ravine during the November storm event and did some additional monitoring.
So we have definitely made some progress, but I will let Doug speak to the schedule when he returns to the
office.
Thank you for your continued assistance on this project!
Lindsey Shepherd Miller
Environmental Engineer
201 S Jackson St, MIS KSC-TR-0231
Seattle, WA 98104-3856
206.296.3762 (p) 206.296.0565 (f)
Lindsey.Miller@k, in eountygov
From: Padgett, Rebekah (ECY) [mailto:RPAD461@ECY.WA.G0V]
Sent: Tuesday, December 20, 2011 10:40 AM
To: Chin, Doug; Joshua Monaghan
Cc: Miller, Lindsey; McGraner, Patrick (ECY); Jason Mirro; Stockdale, Erik (ECY); Olson, Patricia (ECY)
Subject: RE: May Creek Water Quality Samples
Hi Doug and Joshua,
We have been out to the site a few times since we last met to take screening level samples up and
downstream to get an idea of baseline and are planning to take some additional samples once we get
a good rain event or two. At that point we'll have a better idea about what is going on at the site and
can share that information with you.
Has King County consulted with the King Conservation District to discuss which BMPs may be
applicable for specific properties or portions of properties? It would be helpful to hear about any
progress on this.
Doug, what have you learned from DDES about how BMPs could go into local permits? Has Tracy
Drury gained access to the reach downstream to collect additional sediment information? You had
mentioned that Jeff Burke was doing a write-up on Long Marsh and would run an analysis for 100cfs
and that the County was working on a response to Patricia's e-mail—how is that coming along? Let
me know what your timeframe is for getting this information submitted to Ecology.
Thank you all for your efforts on this.
Best,
Rebekah
`]�l� 4{,�(�c.U4_-' CRY OF RENTON
Jean Rollins �� LL a_G - 2 6 t
2905 Ilwaco Ave NE ,,m, S. FEB 0 6 2012
Renton, WA 98059RECErVED
$�
February 6, 2012 /�+w CrTY ctERK'sG�
�G
It;
City of Renton
Planning &Development Committee
RE: King County Appeal of Renton's Hearing Examiner Decision for May Creek
Honorable Councilmembers:
King County (KC) has completely loss credibility regarding downstream impacts from their proposed
project. For almost 2 years, citizens have been asking about erosion to banks. It has now been
revealed no bank erosion modeling has ever been done. It is inconceivable after so much -input by
scientists and citizens that the County still does not have appropriate erosion studies.
KC's Appeal 's finding of facts:
1. Flawed conclusions: Ecology (DOE) clearly documents KC presenting insufficient data -and
reaching flawed conclusions. "...outstanding issues remain: baseline data, and sediment transport
and data about what will happen downstream." (1)
"...flawed in terms of making conclusions based on insufficient information or incorrect data....
{required to provide) an appropriate sediment transport and erosion study (with) independent review..."
(2) The need for independent review suggests a low level of confidence in -the KC studies by Ecology.
On the Octoberl 8, 2011 meeting of KC with Ecology, Dr. Olson provided a 5 -page handout for a technical
discussion on sediment/erosion. (Agenda- 3) Dr. Olson states, "So you have model error compounded
on model error plus an unknown error associated with the sediment data collection." (4)
On the handout, I have highlighted KC`s flaws that are continuing. (4) The most distressing are that KC has no
bank erosion model, data provided does not address ..., not a high level of confidence, only looked at one factor
in erosion, and the potential significance of 7 extra hours. Solutions given by Dr. Olson is collect additional
data, and add a bank erosion model.
Ecology staff meeting notes from the 10-18-2011 meeting between KC and Ecology all support the
need for additional data, greater confidence and lack of erosion modeling. Rebekah Padgett, meeting
notes record: "No bank erosion model; baseline data is insufficient; need samples in the downstream
reach. Need for more data, appropriate modeling and monitoring" (5)
Erik Stockdale, meeting notes record: "There are no bank erosion model in any of the models. 7 extra
hours can make a difference in sediment transport. Do more detailed sampling; separate bank model;
data is not there to address specific assessment. { Get)greater confidence in data. Data is not there to
determine which events will cause a problem." (6)
2. Pebble size argument- Irrelevant since the Sediment Transport Study is only one factor in
determining erosion pursuant to Dr. Olson's' handout of 10-18-2011.
3. Threshold of erosion argument- Also irrelevant as movement of the streambed (bedload) done in
only a few areas is only one factor in determining erosion. Page 4 of Olson's handout, "Banks may
erode even if bedload does not move. Where is the bank erosion model?"
�A
4. KC arguing errors in interpretation is also irrelevant since there is no bank erosion modeling;
factors of erosion have not been studied and the level of confidence is not high.
3. KC argues they have provided extensive evidence to show no adverse impacts downstream. Ecology
had all the documents cited in the KC anneal except the 12-14-2011 memo regarding scour chains.
This new document begins to suggest a way to study sediment changes in the downstream reach, one
of the factors of erosion not yet studied. This is an initial plan alas not the results of a study.
Yet with this array of documents, Ecology denied their permits and stated on page 5 of the denial letter
"...outstanding issues ...Data about what will happen downstream." Members of Ecology staff (Dr.
Patricia Olson, Senior Hydrogeologist, PhD, Erik Stockdale, Unit Supervisor &Wetlands Biologist,
Patrick McGraner. Wetlands Biologist) have seen first hand the erosion downstream. In their scientific
decision to deny permits, they did not deem erosion impacts from this project to be negligible. King
County has not demonstrated to Ecology this proiect will not have downstream impacts, which could
negatively affect water quality.
Legal- Quotes from Dr. Olson's 8-15 memo are laced throughout Ecology's pre -denial letter of 9-1-11
and in the denial letter itself. The meeting on 10-18-2011 focused on Dr. Olson's input in the form of a
handout. Agenda item #4 of the meeting with Ecology and KC on 11-15-2011 is "Discuss 8115111
Olson memo items- scheduled for 90 minutes." (7) Notes of this meeting. Require KC to respond to
Dr. Olson's memo, Project will change the sediment delivery process, No sampling between 143`d and
146`h (8) KC knew Dr. Olson's input was important to their permitting process. If not, why on the
day that their permits were denied did KC ask for a meeting with Dr. Olson? (9) Dr. Olson refutes the
baseline data, the adeauacv of the study, the desijzn ofthe proiect. and the conclusions ofthe proiect.
She refutes KC's threshold of erosion, and concludes that there could be potential downstream
impacts.
This proposal has not met the Citv of Renton's own critical area variance criteria:
5b Public health & safety and welfare are not best served. This project is attempting to drain horse
pastures at the detriment of family homes and sole access bridges. Ecology scientists stated in their
denial letter that KC does not know what will happen downstream. KC has not sufficiently addressed
impacts to downstream flooding and erosion and critical areas of May Creek.
PhD Hydrogeologist, Dr. Olson asserts KC's hydraulic analysis is inappropriate, the County's
conclusion that this proiect will not further contribute to erosion is incorrect and disagrees that the
increase in frequency of smaller floods is insignificant.
These unknown issues (erosion, increased frequency of flooding, sediment transport, sediment
deposition and changing morphology of May Creek) ieovardize the health, safety and welfare of
Renton recidentS jowndrPam
5b5. The proposed action DOES NOT TAKE affirmative and, appropriate measures to minimize and
compensate for unavoidable impacts. The scientists at Ecology purport the models used do not
adequately address erosion or deposition and hence KC does not know what will happen downstream.
Dr. Olson disputes the erosion thresholds, and sediment transport numbers. She Iaments the lack of
accurate studies as to where sediment volumes will be transported, downstream sediment deposition,
an upstream sediment report, geomorphic analysis and an erosion report. She disagrees with the
insignificance of smaller floods to downstream areas.- Ecology states that King County's expertise -
should be consulted and recommends the existing transport modeling should have independent review.
Since baseline data, sediment studies and erosion studies are inadequate or incorrect and downstream
impacts are unknown aanrovriate measures to minimize and compensate for unavoidable impacts are
not possible..
In conclusion, KC has yet to perform an erosion study with the appropriate factors according to
Ecology. As recently as October BY Ecology has discovered KC needs more detailed sampling and has
not done bank erosion modeling. The banks of May Creek are where our at risk homes and
bridges sit. Ecologv as recently as November 15 is requesting KC get more -information of this reach,
and respond to Dr. Olson's questions and comments. Ecology's and citizens' concerns led Renton's
Hearing Examiner twice -to deny KC the needed permits. King County has vet to provide Ecology the -
necessary documents to support their claims of no impacts downstream! The burden of proof is on KC
for a proposal that addresses all stakeholders' concerns to the satisfaction of the City of Rentop,-
Ecoloev and other agencies.
I respectfully request the Planning & Development Committee recommend to full Council that this
appeal. be denied.
Sincerely,,
a{��2olli»g
Enclosures:
Conv of email dated September 22. 2111 from Rebekah Padgett. Ecoloev to Doug Chin King County
October 18, 2011 Meeting Agenda with KC and Ecology
Dr. Olson's Octoberl8. 2011 meeting handout regarding erosion and attached email confirming Dr.
Olson provided this handout
October 18. 2011 Meeting Notes taken by Rebekah Padgett. DOE
October 18, 2011 meeting Notes Taken by Erik Stockdale, DOE
November 15. 2011 Meeting Agenda to discuss Sediment Transport Issues
November 15.2011 Meeting Notes taken by Erik Stockdale. DOE
Footnotes:
(1) "Ecology received King County's responses to the 9/1/11 letter requesting additional information.
While some questions were addressed, outstanding issues remain including buffer, baseline date, and
sediment transport and data about what will happen downstream." (Ecology 9-22 Page 5)
(2) King County... has well qualified fluvial geomorphologists and geologists on staff; however, it does not
apvear that they were consulted for evaluating the sediment transport study. baseline aeoloev and historic
channel form and geomorphic processes that created the current conditions, the downstream channel response
including migration to changes in flow and sediment regimes. The studies upon which the vrovosal is based
appear to be flawed in terms of making conclusions based on insufficient information or incorrect data.
Kine Countv should utilize its geologic and aeomorohic expertise and further evaluate adding samvling points
and designing an appropriate sediment transport and erosion study." Additionally the existing transport
modeling should have independent review because not all sediment transport models avvly everywhere."
.(Ecology 9-1 Pace 5-6)
Note: I have referenced documents in the Hearing Examiner record. In addition, I have provided new
evidence that. "could not reasonably have been available at the time of the hearing before the
examiner" since the documents are dated after the hearing date. All these new documents show KC has
vet to.provide to Ecology the necessary documents to support their claims of no impacts downstream.
Please note KC provided documents dated after the initial hearing date.
New documents:
(3)October 18. 20 11 Meetine Aizenda with KC and Ecoloev
(4)Dr. O1son's October 18, 2011 meeting handout regarding erosion and attached email confirmed Dr.
Olson provided this handout
(5)October 18, 2011 meeting notes taken by Rebekah Padgett, DOE
(6) October 1.8.201.1 meetinr! notes Taken by Erik Stockdale. DOE
(7)November15, 2011 Meeting Agenda to discuss Sediment Transport Issues
(8) November 15,.2011 meetine notes taken by Erik Stockdale. DOE
(9) Copy of email dated September 22, 2111 from Rebekah Padgett, Ecology to Doug Chin, King
Countv
May Creek Drainage Improvement Project # 3
October 18, -2011.
'Agenda:
Time
Topic
Who
1:00 —1:10 -PM
Welcome
Doug Chln,.King County
& Introductions
All
1:10 2:40 PM
Technical Discussion
Facilitated by Rebekah Padgett,
WA Department of Ecology
o Sediment
[Pa#ricia_Olson,-Ecolog
o Buffers
Patrick McGraner Ecolo a
2:40 —.3:00 PM
Next Steps
Rebekah, Doug, All
3:00 PM
Adjoum
tAS sediment transport model
scussfon.on a.number_of important fattors3
#I
• Transport equation used in HEC RAS model? Results compared from all appropriate
equations? Lateral boundaries? Upstream boundary?
• HEC RAS requires that upstream sediment loads are specified 'or they can be calculated
by the model. Which was done? Haw do:knoi+v them, if sediment sources and quantities
uar�_not determined? What are they based on?
• Sediment transport results are strongly dependent on which transport function is
selected and energy slope. Was the default based on Mannings n used or the actual
slope of the energy grade line?
• Did you overwrite the mobility coefficient (varies as to equation used in MPM it is
critical shear stress, Ackers is threshold mobility, Wilcock is reference shear stress)
with specified variables.based on reference data or data representative of this reach? If
so how determined? Theoretical or empirical?
• T IEC RAS manual emphasizes that transport coefficients represent the central tendencies of
the data considered but will not likely reflect the transport of a specific site precisely even if
an appropriate transport function is selected. There_Wa be substantial error -in sediment
transport,
• HEC RAS requires that upstream sediment loads are specified ore they can be calculated
by the model. Which was done? How do know them if sediment sources and quantities
are not determined? What are they based on?.
• No discussion of error. The conclusion of the HEC RAS model is partial and tentative,
because real rivers are not 1D and numerical models are less than perfect expressions
of reality. Then you tie that with Lnadequate sediment data to conduct a hazard related
erosion analysis and there you go. Also you have error from HSPF,.HEC_RAS.hydraulic,
HEC:RAS:se xr ent and -very -limited. sediment -data. So you have model -error.
compounded:on.model error -plus. an.unlmown,error.associated with the sediment data
collection. Not a:hlgh:level:of confidence.
Anchor sediment study
• Data collection and monitoring was focused on three stations (cross-sections of the
creek) located throughout the project reach at approximately RMs 2.9, 3.4 and 3.6. All
sites are downstream of the properties in the upper ravine. What were the criteria used
to determine these locations? What was the sampling design? No discussion of
sampling error based on techniques.
• Station 3 is the more representative but does not provide adequate data to evaluate
erosion on a site specific basis. Nevertheless, significantly more bank recession and
channel movement occurred at this site than the other 2.cWe observed.that the.reach
was=ac�hvely,migrating=with:bank erosion
• The incipient motion calculation was`.interpolated- etween=70--ds.and.350:cfs using a
simple linear relationship. cN_QLapprQpdatgd because it is not a linear relationship as
shown by the transport equations.
The uncertainty with the data was expressed in the study summary:
"It is important to note that there is a fair amount of uncertainty with this value.
To illustrate some problems with limited data, looked at potential to initiate bedlbad
transport by'determining critical shear stress for 3 additional empirical critical shear stress
equations and then used to compare HEC RAS profile data. at different flows..
Channel sheau ;`lb it -2 from Anchor study
Shields Relation
Shields Relation .
Ashworth and Ferguson
i 1989
dell
d50
d70
d10 d50
d70
Station 1 0.8
1.0
1.9
1.0 1.8
2.4
Station 2 0.5
0.5
0.7
0.6 0.9
1.1
Station 3 0.5
10.4
0.6
0.6 0.8
10.9
Convert channel shear in lb ft -2 to Channel shear in N m -z
N re
Shields Relation .
Ashworth and Ferguson (1989)
Station
defF d50
d70
d10
dS0
d70
1
38.304 47.88
90.972
47.88
86.184
114.912
2
23.94 23.94
33.516
28.728
43.092
52.668
3
23.94 19.152
128.728
1 28.728
1 38.304
43.092
3 additional shear stress estimates
Shields (0.QS6) Parker 1990
Miller 1977
d5a
d70 d50
1 d70
d50
d7o
Station 3 25.4
38.1 134.8
36.2
20.4
130.1
WdrauHe Radius and Total Shear Stress far Nigh Maw events IMndekadl firm enrhnr ehufw
Return
Flow in
-
_
Period
Creels (cfs)
Rh (ft)
Ts (1b/ft2)
N nf2
range f°r D50 at site 3, 20.438.4 N
(years)
of ' N=S, Potential for initiation
Mean
Annual
13.6
0.4
0.7
33.516
Yes within range
2
208
1.2
1.9
90.972
Yes
5
243.
1.4
2.1
100.5
Yes
10
347
1.7-
2.6
124.488
Yes
20
429
1.9
2.8
134.064
Yes
Cross-section specific HEC -RAS model (from Anchor study)
Profile
Channel stress ib ft'
Channel stress N
D50at 20.4-38.4 N m: N-5
m 2
Potential for Initiation
^'-*L•.;
:•—y .ii r".Nils
Izt� Y
8yam
.,a 9.._
�'17� —_�1-
? 1q'slR ta.}. �•• I4{�4! :?.
2756.00
0.08
3.83
• No
2746.00
0.09
4.31
No
2741.00
Bridge
2736.00
'0.09
4.31
No
yyyy'� s -. Z
buy
_�:�lLL ��y��1(�i�I� .cy�s3s'�r•Y - %
.M1Cni'3j Yrt�ui-' ��j
_.��..-i� � }�S��J� {,�%Vti- _H,L.
2440.0
0.03 •
1,44
No
1964.00
0.14
6.70
No
C1�- ..r
- �.
� �1�}�T��y4���''sr�
l,tn .1�4�.. _..
t_L�ti��t'`��tl�-Yri.FiatCv:OM
72 cfs
,1 ant _ �-. .. _.ci '.♦ - Yf �l.:rsJ �
@IC � -_ v>`. �'si� .._
�m .
�+P'��E7��•HSa`_ci
- fi_ .v_a.�y .rte �} vs, _.irrt�, __
r'a. "���;.,G•-�7,'i�Y•i.�:'�� -Rcic'_s
.:a ij^'Lx�'u
_ _ .-.••.• —
t����
a• L:Y2-n3uii�iSlL.tIS
rtin i. i; 'd"3..:�._nt , 4`ry
2756 0.23
1.1.0124
No
2746 0.28
13,4064
No
2741 Bridge
No
2736 0.29
13.8852
No
- •-
E
y
- 4`
M
�'>w�ys�rl
,
.I.a�,,m'��iiM1Y'A�a'l•�
is
n:+r}7�S:}t.kY%s
M�+m
2440 0.07
3.3516
No
1964 0,34
16.2792
No
k''-"ivi ak 'id. .1a.- i. ai. 15
s ' z .�,ys
- 3w� •� i ` i*
..XY ..'b°�1�c�`+r4�-b.�1:'
MEN
rli i
r* Tsa ije_ 'r' Hd�
ME
Reach average 0.55
26.3
Yes, within range
While one reach with obvious bank erosion appears to have similar sediment size
distribution to Anchor site 3 (Photo 1 and 2), there are substantial variations among
proi3les. This analysis illustrates that 1 measurement for a long reach is not adequate to
evaluate site specific incipient bedload transport which is one piece of information needed
for a hazard assessment
The above simple analysis illustrates the limitations of the 3 point data In evaluating
specific sites. But more Importantly, critical shear stress and Incipient bedload
transport calculation is lust:ane:factor-.In-erosion:and:channel-movement-
Temporal and spatial influence on sediment transport Indicate that increased flow
event durations such as 7 extra hours per year for a 400 cfs storm 6 hours per year
for a 7S cfs storm ccould-be-very_s1iji ficannl should additional sources of sediment
from armor break up, bed mobilization and bank erosion be added
• Sedload transport is known to be highly unpredictable. One reason is time varying
passage of upstream sediment causes fluctuations in rate.
o The supply of sediment available to be transported is known to be a function of
both temporal and spatial variations in entrainment characteristics (cluster,
armoring and patches) of the channel bed. In supply limited rivers (as May Creek
ravine reach was described), the sudden availability of new sources ofbedload
from armor break-up, bar mobilization or bank collapse, may become locally
Important Such variability is reflected in the high degree of scatter recorded in
bedload transport datasets, although it seems particularly pronounced in supply
limited humid -temperate streams.
• Sediment heterogeneity increases variation in bedload transport in time and space
within one flow event.
0 1-D models, such as HEC RAS, results represent instantaneous, rather than time -
averaged, critical shear stresses.
o Equal mobility influences sediment transport in armored beds.
■ This mechanism Is most often observed in reaches with a coarse armor
layer in which coarse particles are exposed to the surface that provides
them with an increased chance of transport. Fine particles are hidden
below the surface where their transport probability is diminished. Thus,
the preferential exposure of larger particles in the armor layer acts to
equalize the mobility of coarse and fine particles and eliminates most of
the differences in the mobility of small and large particle sizes. Once the
small particle sizes are mobilized they increase entrainment and
transport of larger particles.
• An important element in the process of bedload transport Is the extent to which local
vs. remote sources of supply interact with the sequence of flows to create temporal and
spatial variability in transport at a section.
o As water levels rise additional sediment sources (armor break up, bars, banks)
and recedes (banks) become available. But they also establish connectivity between
sediment sources over much longer reaches of channel.
o The duration of flow over the critical threshold for transport and where the
sediment sources are within the upstream reach strongly influences interaction
with sources and connectivity along a reach.
• Given the above sediment transport characteristics as influenced not only by magnitude
of event but also duration, duration is an important factor to sediment transport and
bank erosion�The:data:provided�by-King-County does not address.ahy of.these.
CBanks__Y Ay erode_—eve n.if.hie- dload:does aot:mpve esp"Ily where basal erosion is
already occurring (photo 2).LWhere is #lie. -ir–osioa.niddei?
• Sediment transport occurs in the longitudinal direction AND transverse directions.
Both affect bank erosion. HEC RAS cannot predict in transverse direction nor can it
model for channel migration -
• Bank erosion consists of two interactive physical processes: basal erosion and bank
failure. Basai:erosion=(Photo 2, 3) refers to the fluvial entrainment of bank material (in
this case consisting of smaller sediment size) by flow -induced forces that act on the
bank surface..-falluMoccurs due to geotechnical Instability (e.g. planar failure,
rotational failure, sapping or piping).
i
The rate of bank erosion traditionally is calculated empirically from the geometry of
channel bends, bank material, and flow intensity.Hank•failure can.occur_before_bedload .
transportt s initiated.
These modes of failure have distinct characteristics, and an investigation must be
conducted to -determine the specific mode of failure Because this is often indicative of
the underlying problem at a site edttve urvice s o through the installation oof bank pins.
or system of time, and 2) to monitor
changes at specific points by rep Y
The first approach offers the benefit of providing immediate results for average
bankline retreat, while the second method provides insight into event -specific bank
loss.. Because erosion tends to be episodic, periods of 10 years or greater are
recommended for aerial photograph time -series analysis as well as bank pin
monitoring.
Banks also erode during bedload movement especially in meandering or migrating
streams. Whether a bank retreats or advances depends on the balance of sediment load
at near -bank regions where sediment may come from upstream, bank erosion, and
secondary Sow. The strength of secondary flow in redirecting bedload transport
correlates with the local radius of curvature as well as sinuosity of meandering
channels. Flow momentum_redistribution causes bed degradation near concave banks
and deposition near cofivek� anks. Bed banks. This causes ticoncaon vebens anks to retreat as bank
and
deposition stabilizes cone
erosion occurs, while convex banks ad4ance with the build-up of point bars. tThim
process:occurs within_the.reach_between Lyons and_>r43 gtxeet:Bridge:�
�+cC-
Clarification about the source of the a i ocument (attached; first paoe, first line is `LHEC-RAS
sediment transport_ model"). This was distributed by Dr., -Patricia, Olson at th 1e� 0118111
meeting with King County staff -I
If you determine.that you would like anvthino further, please contact both Sallv Perkins and mvseif.
Thank you,
Rahakah
From: Padgett, Rebekah (ECY)
.Sent: Monday. January 30, 2012 9:32 AM
Kay Creek Drainage �r:rro�;e�:r:eProject
October 18. 2011
Agenda:
Time Topic who
1:00-- 1:10 PM Welcome Doug Chin, King County
3Introductions All
1:10 -- 2:40 PM
Technical Discussion
Facilitated by. Rebekah Padgett,
WA Department of Ecology
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- f o Sediment-
Patricia Olean, Ecology
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Next Steps w
Patrick McGraner, Ecology
2:40 '-- 3:00 PM
`" Rebekah, Doug, All
3:00 PM
Adjourn
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AGENDA # 4.
May Creek Drainage Improvement Project
Date: Tuesday, November 15, 2411
Time: 10:30 12:30 p.m.
Location: Room 3J
Attendees: Don Althauser, Jeff Burkey, Julia Turney, Tracy Drury by phone, Patricia
Olson, Eric Stockdale
Purpose: Discuss Sediment 'Fransport issues
■■r rrrrrrrrrrrrrrsrrrrrrrrrrrrrararrrrrrrrrrararrrrarrrrrarrrrrrrrrrrrrri
1. Introduction 1 mm.
Review purpose of meeting and agenda.
2. Overview 15 mug.
Valley -Julia Turney
Ravine Tracy Drury
Hydraulics and Hydrology Burkey
3. Anchor Study -Drury 10 min.
Basis of monitoring
4. Technical.Discussion -All C. M0
. . �Discuss_g1,1Sl.1.1✓01soa memo-items=and=existing-info=available-and analysis.
5. Other items
5 min.
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May creek Drainage Improvement Project Decision
From: Padgett, Rebekah (ECY)
sent: Thursday,fg'September 22; 2011]2:58 PM
To: 'Chin, Dou��
cc: stockdale, Erik (ECY)
Subiect:• Mav Creek Drainaae Improvement Proiect Decision
Attachments: MAY CREEK -401 -WO CERTIFICATION ECOLOGY DENIAL.odf
Hi Doua.-
Thank you for your time this afternoon to discuss the May Creek Drainage Improvement
oroiect.- As oromised. attached is Ecoloav's decision—
once -
once I have had a chance to check with patrici.aaabout her schedule, I will follow up
with you to �et_uD- a. meeti no. -
Best,
Rahakah•
Pape 1