23 May 2011
To: City of Everett, Ryan Sass rsass@ci.everett.wa.us and Tony Lee tlee@ci.everett.wa.us
From: Everett Valley View lower rim neighborhood (see signature list below), Everett 98203
Dear Mr. Sass & Mr. Lee:
This letter addresses the recent landslide activity in the Panaview and Burl areas of Valley View.
As the city is aware, the landslide has been disastrous and adversely affects the lives of the local
residents. We, the residents and signees below, are presenting evidence that we believe the root
cause of the deep-seated landslide is excessive water being deposited into the creek below our
neighborhood by the Valley View neighborhood storm water drainage system. The water caused
constant and accelerated erosion of the ravine slope toe. We also believe the City of Everett is
responsible for this event due to the 2004 “Panaview Blvd Storm Drainage Project” (City of
Everett, 2004) in which the city nearly tripled the capacity of the storm water drainage system
and apparently did not take any measures to mitigate the increased creek water flow.
As such, we request the following actions by the city:
1) Stabilize the toe of our slope and fortify the creek bed to minimize or alleviate further
erosion.
2) Stabilize the top fracture of the slide (scarp) which runs from 3021 Burl to 3001
Panaview. One proposed solution is to install an effective retaining wall the length of the
scarp.
3) Rebuild the 3019 Burl house (currently totaled – Photo 1) and repair the 3007 Panaview
house (foundation is undermined – Photo 2).
3019 Burl Place
3007 Panaview Blvd
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BACKGROUND:
Testimony of long-time residents indicates the creek below us in the ravine used to be dry in
summer and a slight stream in winter. One neighbor reported, “You could easily step over it”.
The creek now flows year-round. The Valley View neighborhood and storm water drainage
system was built in 1968 with the outflow being an 18 inch diameter pipe exiting runoff water
into a “grass-lined swale” (the creek as it currently exists). Since 1968 more and more
development occurred in Valley View causing increased storm water runoff and resultant
accelerated erosion of the ravine.
Our ravine situation appears to be described in great detail in the Snohomish County report
“Marshland Tributaries and Sunnyside Creek Drainage Needs Report” dated December 2002
(Snohomish County Public Works, 2002). Note that our creek, which is a “Marshlands”
tributary, is just north of the report study area. Chapter 6 and Appendix E provide an excellent
summary of the situation. Essentially urban development in the upper portions of the ravines
above the Snohomish Valley Marshlands area resulted in the deposit of storm water into the
ravines which greatly accelerated erosion in an already fragile environment. With increased
development the storm water systems were overwhelmed with the increased quantities and
flooding occurred. This resulted in greater erosion rates and enhanced deep-seated landslide
potential.
Valley View experienced multiple floods in 2003/2004 which resulted in the city increasing the
storm water drainage system capacity. The outlet pipe is now 30 inches in diameter. However,
it appears that minimal precautions were taken to protect the creek or ravine. As well, upon
examination the outlet appears to be assembled incorrectly, creating an obstruction that leaks
underneath and forces spray onto the neighboring banks. This examination was performed by a
professional builder of such pipe assemblies.
The City of Everett “Landslide Hazard Critical Areas Map 2” (Reference 3) shows our ravine as
having a landslide hazard rating of “high” to “very high”. Even prior to the 2004 project it was
apparent that erosion was a concern. The people responsible for the Marshlands apparently have
been dredging the canal that our creek exits into (east side of Larimer Road) yearly or every
other year due to the accumulation of sand/silt.
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Our field samples (Photo 6), taken in 2011,
indicate that water comes into the creek
(storm water pipe exit) clean/clear and exits
on the valley floor a murky gray color.
During hard/steady rain periods the valley
floor exit flow is very murky – it is so high in
particulate matter that it resembles chocolate
milk (Photo 7) We are surprised this silt flow
is allowed since our creek drains into
Marshlands and shortly thereafter into the
Snohomish River which is salmon bearing.
We have been told by a witness to the
yearly/bi-yearly Marshlands canal dredging
that the removed material is always a gray
silt/sand. This correlates with canal bottom
samples we have taken this year.
In addition, a video from August 2004 recording the creek exit water at Larimer shows the same
gray color we see today. We believe the sand/silt being continuously washed away is glacial
advance outwash sand/silt and glacial till being eroded from the hillside. We have taken samples
from the creek and near our houses, and both the advance outwash sand/silt and till dissolve
easily in water and result in the gray water color seen at the creek exit.
RELATED TIMELINE:
Late 2004 – City increased flow capacity of stormwater drainage system.
Jan 2006 – 3021 Burl Pl (built 1975) notices house movements for first time.
Jan 2009 – 3007 Panaview Blvd (built 1978) notices house movement for first time (original
owners).
Dec 2010 – present: Dec - Start of deep-seated landslide. 3021 Burl resident vacates house in
Feb & 3007 Panaview residents vacate in March. Landslide scarp extends from 3021 Burl (built
1968) to 3001 Panaview (built 1985), slide continues to move slowly. 2933 Panaview, whose
backyard is at the pipe exit, indicates that since pipe size increase they have lost approx 6 vertical
feet of their backyard (land has “dropped”). Prior to pipe increase no noted land loss noticed.
Creek - Current Conditions:
A deep-cut chasm in many areas and the extreme vertical
drop to the valley floor makes hiking the creek very
difficult. Also, it is dangerous due to numerous landslides
into the creek. The creek begins at the storm water exit
pipe (Photos 3 & 4), which dumps water onto a bed of
rocks (riprap). However, immediately downstream of the
riprap the creek bed is clay (Photo 5). This means that all
layers above the clay (advance outwash sand/silt, glacial
till, recessional outwash, and colluviums) have washed
away. The clay layer seems very water resistant; our
samples in water do not dissolve very easily. During
heavy rain periods water shoots out of the pipe and some
of it totally bypasses the riprap and lands directly on the
clay. Continuing down the creek it becomes evident that
erosion is rampant as the creek bed is a mixture of
decomposing sand/silt and till. Several landslides have
closed the creek chasm and midway down is a fairly large
landslide which has re-routed the creek. This is near the
area where several (perhaps 10) 100+ year old Douglas
Firs (the rings of two stumps were counted – there were
approx 120 rings) and at least one Cedar have fallen, been
cut down, or are in the process of falling (Photos 8 & 9).
The creek erosion and landslide decimated these trees. The
creek and trees at this point are on the 7720 and 7818
Larimer Road properties. The creek continues with
additional landslides around it down to the valley floor.
The only stretch of the entire creek not distressed is the
last 40 feet or so prior to entering the pipe under Larimer
Road (Photo 7). In this 40 feet run the creek is fairly level
whereas the rest of it has a continuous vertical drop.
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NOTE: Approximately 10 100+ year old trees falling or fallen would seem to indicate a 100
year event. Although there has been lots of rain this year, we have not noticed any other Puget
Sound area experiencing a 100 year event.
ROOT CAUSE:
Based on our observations, studies, discussions with professionals, and field research we believe
the 2004 storm water system capacity increase has resulted in excessive creek water flow and
destabilized the entire ravine below our neighborhood. The creek, whose bed is at the clay layer,
is continuously eroding the toe of the ravine and effectively allowing advance outwash sand/silt
and glacial till to “bleed” out of the hill. Perhaps augmenting this scenario is underground water
flow from above our houses which, due to the “open wound” at the ravine toe, is flushing
outwash sand/till down the slope. We are unsure of the source of the water (whether it is natural
or perhaps coming from another source such as a leaking sewer, water supply, or stormwater
system).
We understand the City of Everett has hired a geotechnical engineering firm to assess the
landslide situation, and we wonder if they have reached the same conclusion. In a neighborhood
meeting the Mayor mentioned those reports are public record and that we were welcome to look
at them.
CITY NEGLIGENCE:
We believe that the city’s Valley View storm water system capacity project in 2004 did not
properly assess the impact to the creek and ravine and did not mitigate the increased water affect.
Our public disclosure request (PDR) regarding the project indicated that the Everett “Stormwater
Management Manual” dated January 1997 (Reference 4) was the applicable city document which
provided rules/regulations for the 2004 storm water project. In our opinion and of critical
importance, the project should have included creation of a Stormwater Site Plan (SSP) and a
Drainage Plan (DP). Using the guidelines in these plans the city would have assessed in detail
any potential affect to the creek. However, the city indicated these documents were not created,
nor corresponding processes followed, since they determined the project scope was not within
the guidelines which require the documents or procedures. The two guidelines are “Land
disturbing activities of one acre or greater” or “Creation of 5,000 square feet or more of
impervious surface”.
According to the city-provided engineering documentation (Reference 5), the Panaview storm
water drainage system drains an area consisting of 112 acres, of which 41 acres are considered
impervious. The drainage basin includes most of Valley View, some of Sylvian Crest, an area
under I-5, and a portion of the neighborhood west of I-5. The impervious surface area of 41
acres is equal to 1,785,967 square feet. We are still reviewing the city-provided flow
calculations for the project, but for discussion purposes consider an example that the system
capacity was increased by 1%. This is equivalent to adding 17,860 square feet of impervious
surface to the drainage area. The city greatly increased the capacity of the system, and although
we realize maximum capacity flow may not be seen at all times, it is obvious that the expected
increased flow from the project far-exceeded the equivalent of “5,000 square feet” and therefore
qualified for the intent of the SSP and DP requirements. An equivalent analogy to the city’s
apparent logic is that a neighboring drain basin storm water system of the same size could be
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added to the Valley View storm water system with the addition of a new pipe run which merges
the two systems. The pipe-run project itself does not exceed the 5000 square feet or one acre
guidelines, but obviously the outlet flow is doubled and qualifies for the intent of the SSP and
DP requirements. We also have internal city correspondence from 2003 (before the project) that
indicated “some kind of an allowance for channel improvements downstream of the outlet”
should be considered as part of the cost estimates for the project.
The ravine area landslide potential was classified as “high” or “very high”, Snohomish County
Marshlands has been dredging the creek outlet ditch for years, it should have been no secret that
excessive erosion was already occurring prior to the pipe enlargement. Increasing flow would
obviously have increased this. In winter 1996/1997 the ravine experienced surface landslides
(not deep-seated – these surface slides were due to saturated surface soils) due in-part to slope
steepness. The city should have been very cognizant of the ravine and creek vertical drop. It is
also our understanding that in 1996/1997 a City of Everett sewer system project in our
neighborhood (Lift Station No. 10 By-Pass – Reference 6) considered a new sewer pipeline route
which would have run directly under the slope just north of our ravine (under the house on 2927
Panaview and down the slope), however a different route was chosen due to slope landslide
concerns.
SUMMARY:
The city should have followed the Storm water Management Manual SSP and DP procedures.
They should have known our ravine was landslide-sensitive, and should have properly mitigated
the effects of the 2004 creek water flow increase. They did not, and now we have a deep-seated
landslide which we believe is directly attributed to this event. We would like the city to right
their wrong.
FINAL REMARK:
Per the Snohomish County Marshland report, “Where increased bank undercutting has
caused hillside landslides, it could take decades to centuries of erosion before the
hillslopes recover a stable geometry and pre-development erosion rates”. Accordingly, we trust
the city, as servants of the people, will act in an appropriate and timely manner to resolve this
issue. We hope creek/slope/house mitigation actions can occur prior to the next rainy season
(Winter 2011/2012) before further damage is sustained.
Thank you for your consideration and time. We look forward to the City of Everett’s response
within 14 days.
Sincerely,
Don and Charlotte Benusa
Tim and Dee Smith
John and Sherry Priest
Dave and Diana Herbert
Ken and Donna Bosman
Chuck and Joyce Thompson
Dmitriy and Galena Krasinsky
2913 Panaview Blvd
2917 Panaview Blvd
2921 Panaview Blvd
2925 Panaview Blvd
2927 Panaview Blvd
2931 Panaview Blvd
2933 Panaview Blvd
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Chuck and Karen Kinman
Jay Himmelman and Sue Habeck
Rob and Margaret Lund
Steve and Diane Mosman
John Vicente
Dick and Shirley Frohne
3001 Panaview Blvd
3005 Panaview Blvd
3007 Panaview Blvd
3013 Panaview Blvd
3019 Burl Pl
3021 Burl Pl
(Signatures on file)
Photos
Photo 1: 3019 Burl Pl
Photo 2: 3007 Panaview Blvd
Photo 3:
Stormwater pipe exit (Creek beginning)
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Photo 4: Pipe exit overshooting riprap
and landing directly on clay
Photo 5: clay creek bottom (same
location as Photo 4)
Photo 6: Water samples
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Photo 7: Creek
bottom just above
Larimer Road
Photo 8 (Aug 2010)
Note group of 100+ year old trees
Photo 9 (May 2011)
Most trees are gone
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References
1) Panaview Blvd Storm Drainage Project – 2004. City of Everett project in which the capacity
of the Valley View stormwater drainage system was increased (including outlet pipe changed
from 18 inches diameter to 30 inches diameter).
2) “Marshland Tributaries and Sunnyside Creek Drainage Needs Report” dated December 2002,
published by the Snohomish County Public Works Department Surface Water Management
Division. The report can be seen at:
http://www1.co.snohomish.wa.us/Departments/Public_Works/Divisions/SWM/Library/Publicati
ons/Urban_Drainage/DNR/marshland_sunnyside_dnr.htm
3) City of Everett “Landslide Hazard Critical Areas Map 2”
http://www.everettwa.org/default.aspx?ID=885
4) “Stormwater Management Manual” dated January 1997, distributed by City of Everett Public
Works Department
5) “Panaview storm system engineering analysis done for Mark Sadler by Jane Zimmerman”
(part of 2004 panaview stormwater project PDR data package)
6) Hong and West Associates, Inc (HWA), “Results of Stage 1 – Preliminary Geotechnical
Evaluation, Lift Station No. 10 By-Pass, Everett, Washington” consultant report prepared for
the City of Everett Public Works dated April 18, 1996 and “Geotechnical Report Lift Station
No. 10 By-Pass, Everett, Washington” report dated September 30, 1997.
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