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CONTINUING EVALUATION OF HDPE
PIPE FOR MARINE OUTFALLS
Prepared by:
Jeffrey A. Lundt, P.E., Kimberle Stark, Wade
Phillips, Tim O’Leary & Baker McCullough
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PRESENTATION OUTLINE
• Brightwater Outfall Description
• Outfall Inspections
• Material & Habitat Study
• Habitat Results
• Material Results
• Where do we go from here?
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KING COUNTY WASTEWATER TREATMENT DIVISION• 5 WWTPs
• West Point
• South
• Brightwater
• Carnation
• Vashon (2)
• 47 Pump stations
• 26 Regulators
• 38 Overflows
• 4 CSO treatment plants
• 391 Miles of sewers
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BRIGHTWATER TREATMENT & CONVEYANCE SYSTEM
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How many utilities have marine outfalls?
River outfalls?
How many are using HDPE for the outfall pipe?
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BWMO CHARACTERISTICS• 420 feet 84” polyurethane lined/coated steel pipe
w/ICCP
• Sheet pile & concrete seismic anchor
• Wye transition
• 2 - 63-inch OD HDPE pipes 5,018 & 4,768 feet
long (DR 21 & 26)
• 494 feet buried, remaining bottom laid pipe
• 250 foot long diffuser on each, staggered
• Flow range is 8 MGD low flow – 170 MGD peak
WWF
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MARINE OUTFALL OVERVIEW
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MARINE OUTFALL PLAN/PROFILE
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BRIGHTWATER MARINE OUTFALL PROFILE
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OPERATION & INSPECTION OVERVIEW
• Outfall built in 2008
• Operational in 2012
• High degree of biological
colonization noticed early
• 10 Year study created
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BWMO MONITORING
• Annual visual inspection with
Remote Operated Vehicle
(ROV)
• King County research vessels
Liberty or Sound Guardian with
small ROV
• In year 2, 5 & 10 using work
class ROV and salvage
contractor barge
• 5 year diffuser elevation
survey
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ANNUAL VISUAL INSPECTIONS
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TOOLS OF THE TRADE
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100 FEET
2008
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300 FEET
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600 FEET
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100 FEET VIDEOS
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300 FEET VIDEOS
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600 FEET VIDEO
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POST DEPLOYMENT STUDY
• No previous long term
information
• Three primary goals
• Determine if marine life
had an affect on the HDPE
• What colonizes on the
HDPE
• Determine what effect the
pipeline has on marine
habitat - Pipe good? Pipe
Bad?
• Mitigation credit
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STUDY DESIGN
• 2 ft x 1 ft sections of pipe
deployed in 2012
• -100, -300, -600 ft MLLW
• Reference site (-600 ft)
• 10 “settlement plates” for each
site
• 3 replicates to be collected at
each depth year 2 & 5 and 4 in
year 10
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SAMPLE RETRIEVAL• ROV collection
• Samples assessed for %
cover
• Flexible mesh grid aids in
estimation - 21 cells
• Macroscopic biota identified
in the field
• Photographs of each cell
• Future identification
• Better estimate of %
cover
• Structural integrity tests
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PRELIMINARY RESULTS 2014
• Diversity increased
past 100 ft
100 ft
300 ft
600 ft
0
5
10
15
20
25
30
100 ft 300 ft 600 ft 600 ft Ref
Chlorophyta
Porifera
Cnidaria
Platyhelminthe
s
Annellida
Bryozoa
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PRELIMINARY RESULTS
Chelyosomasp.
Schizoporella sp.&
Spirorbis sp.
Strongylocentrotus sp.
Harmothoesp.
Crisia sp.
Chlamys hasta
Chlamys rubida
Trichotropsis cancellata
Tubulipora sp.
Pododesmus macrochisma Serpulidae
Delectopecten vancouverensis
Urticina crassicornis
Hiatella arctica
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2014 SAMPLE 100 FEET
• Least Diverse
• High % of barnacle scars
(52.1% coverage)
• Avg. total % cover was
56.3%
• Avg. % cover for live
organisms was 4.2%
• Barnacle settlement was
substantial however,
predation likely limited the
presence
• It is expected that
recruitment of new
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2014 SAMPLE 300 FEET
• Tube worms were the most
abundant
• Live barnacles 0.03%
• Total percent cover 47.9%
• Due to the presence of
dead barnacles
• 19.6% cover of live
organisms
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2014 SAMPLE 600 FEET
• The coral bryozoan was seen
at lower depths but not at
600ft
• The scallops were recently
settled (small), not seen at
other depths
• Few motile organisms
• Total percent cover at this
depth averaged 60%
• percent cover of live
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2014 SAMPLE 600 FEET REFERENCE
• The most motile
organisms
• Total percent cover at this
site averaged 67.8%, the
highest of all four sites
• Percent cover of live
organisms is 25.2%
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AVERAGE PERCENT COVER OF NON-MOTILE ORGANISMS BY
PHYLUM FOR ALL SITES
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AVERAGE PERCENT COVER OF MOTILE ORGANISMS BY PHYLUM
FOR ALL SITES
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STRUCTURAL ANALYSIS OF 2014 SAMPLES• Uponor, the pipe
supplier, provided the
samples
• Inspection team
fabricated stands and
racks
• Uponor agreed to do
testing and provide
data in exchange for
the marine
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STRUCTURAL ANALYSIS 2014 SAMPLES
• Uponor’s QA material
testing lab in
Saskatoon,
Saskatchewan.
• Samples tested for:
• Tensile strength,
• Flex modulus @ 5%
strain,
• Flex modulus @ 2%
strain,
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3740
32
0
10
20
30
40
50
Fle
x M
od
ulu
s, M
Pa
Sample Depth
100 Ft. 300 Ft. 600 Ft.
Reference minimum flex modulus-5% value for Uponor’s solid-walled HDPE (20 MPa)
FLEX MODULUS @ 5% STRAIN – 2 YEAR
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11211201
1099
0
300
600
900
1,200
1,500
Fle
x M
od
ulu
s, M
Pa
Sample Depth
100 Ft. 300 Ft. 600 Ft.
Reference minimum flex modulus-2% value for Uponor’s solid-walled HDPE (758 MPa)
FLEX MODULUS (SECANT) @ 2% STRAIN – 2 YEAR DATA
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27.931.5 32.2
0
5
10
15
20
25
30
35
Te
nsile
Te
st, M
Pa
Sample Depth
100 Ft. 300 Ft. 600 Ft.
Reference minimum tensile strength value for Uponor’s solid-walled HDPE (20 MPa)
TENSILE TEST
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121.7109.7
122.1
0
25
50
75
100
125
150
OIT
, M
ins
Sample Depth
100 Ft. 300 Ft. 600 Ft.
Reference minimum tensile strength value for Uponor’s solid-walled HDPE (80 mins)
OXIDATIVE INDUCTION TIME
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CONCLUSION• It does not appear that the effluent has had a
substantial impact on the biological
colonization and composition of the plates.
• The outfall pipe made a habit for marine life
• HDPE pipe was found to be above baseline
strength
• Numbering & marking on weights & ports is
quickly hidden by marine growth
• 10 year’s data should provide good info for
habitat evaluation
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COMMENTS & QUESTIONS
For more information please contact:
Jeff Lundt
206/477-5582