HOLOLANI CONDO SHORE PROTECTION

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SHORELINE PROTECTION
HOLOLANI CONDO
SHORE PROTECTION
LAHAINA, HAWAII (MAUI)
Application: Previous shoreline protection measures
at an oceanfront condominium resort in Maui,
Hawaii were jeopardized without proper scour
protection. As a resul t the shoreline had eroded to
within 15 feet of the hotel deck. Befo re the bea ch
could be returned to the “hea venly” sands its name
impl i es, a tempora ry emergency a pplication was
needed to defend against the erosive forces of
wave activity with a fast turnaround.
Site Conditions: While the Pacific coastline
offers a spectacular view of the islands of Lanai
and Molokai, the beach itself extends only tens
of feet from the waterline, offering limited space
for construction activities. It was intended to
have production setup onsite so that installation
could transpire promptly and simply.
Alternative Solutions: Gabion containers were
considered as a soil erosion “sea wall” for earth
retention, however many gabion solutions are
fabricated from steel, which can easily corrode
in and around salt water. Stainless steel options
were available, but none were as attractive in material
selection or cost as the chosen polypropylene.
The Solution: Due to the successful track record
of marine mattresses in similar scour protection
applications and the urgency with which a new
solution was needed, Sea Engineering, Inc., the
coastal engineer, chose Triton® BX Filter Ma t t resses
for the job. The mattresses would be used as a
foundation structure for the sand-filled geotextile
bags that were installed for erosion protection.
The Challenge: While weather climates are typically
calm and mild, infrequent northwest swells and
Kona storms can app roach the island quickly and
unexpectedly. Lo cal authorities preferred that the
scour protection solution hold up in all weather
conditions. As a result, un confined stone, or riprap,
could not be an option considered for installation.
The project was designed for a five-year lifespan;
enough time to acquire permits for a more permanent
solution. Tensar® Biaxial (BX) Geogrid, manufactured
from a st ress resistant polypro py lene, provided
the h o usi ng for the Triton Filter Mats, which we re
then filled with armor stone. Geotech Solutions
supplied the materials and fabricated the mattresses.
PROJECT HIGHLIGHTS
Project:
Hololani Condo Shoreline Protection
Location:
Lahaina, Hawaii (Maui)
Installation:
Summer 2007
Product/System:
Triton® Biaxial (BX) Filter Mattress
Quantity:
129 Triton® Mattresses
Owner/Developer:
Hololani Condo Association
Design Engineer:
Sea Engineering
General Contractor:
Nielson Construction
Construction Management:
Allana, Buick and Bers, Inc.
Materials Supplier:
Geotech Solutions
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SHORELINE PROTECTION
The installation required a slight learning curve,
but within a couple of days, the system was rolling
out smoothly. Eight-inch thick mattresses were
placed on a firm clay/coralline substrate with 10 ft
by 5 ft sand bags atop, then another layer of mats.
In to tal, 114 ma t t resses we re installed shore si d e
and another 15 were used to create a 3:1 ramp
for shoreline protection between two properties.
The Triton System Advantage: The project
owner and consultants selected Triton BX Filter
Mattresses because of their:
• Flexibility to maintain contact with the
subgrade in changing conditions
• Ability to completely contain the stone fill,
allowing for no mess on the beach
• Design flexibility; the engineer was able to
select the exact thickness and length of the
mats needed to resist the design wave
• Strength to accommodate the site's strong
tidal currents due to Tensar Geogrid fabrication
• Scour protection beyond the seawall footprint
Sea Engineering’s Coastal Engineer Jim Barry
remarked, “The Triton Filter Mats provided
excellent scour protection. As the mattresses
settle their protection increases, ke e p i ng the sand
bags from rotating.” The mattresses mimic the
natural beach by carrying sand through their
porosity – a main advantage according to Barry.
Three days a fter installation co m ple ted, the Maui
island was hit by a nort hwest swell. Winds turned
to ga le force southerlies ove r the next two days
producing heavy southerly seas and immense
rain. It was reported that the Triton Mats took a
“beating” but held up strong!
Additional Information and Services: Tensar
International Corporation, the leader in geosynthetic
soil reinforcement, offers a number of integrated
marine systems. Our products and technologies,
backed by the most thorough quality assurance
practices, are at the forefront of the indust ry. Highly
ada p ta ble, cost- e f fe c t i ve and insta llation-friendly,
they provide exceptional, long-term p e rformance
under the most demanding conditions. Our support
servi ces include si te evaluation, d esign consulting
and site construction assistance.
For innovative solutions to your engineering
challenges, rely on the experience, resources
and ex p e rt ise that have set the indust ry standa rd
for more than two decades.
For more information on the Triton Coastal & Waterway Systems or other Tensar Systems,
call 800-TENSAR-1, e-mail [email protected] or visit www.tensar-international.com.
Distributed by:
Tensar International Corporation
5883 Glenridge Drive, Suite 200
Atlanta, GA 30328
1-800-TENSAR-1
www.tensar-international.com
©2008, Tensar International Co r p o ration. Ce rtain pro d u c t s and/or appl i ca t i o nsdescribed or ill ust ra ted herein are pro te c ted under one or more U.S. patents.
Other U.S. pa te n t s a re pending, and ce rtain foreign pa te n t s and pa tent appl i cations may also exist. Trad e mark rights also appl y as indicated herein. Final
dete r m i nation of the suitability of a ny i n fo r mation or ma terial for the use co n te m pla ted, and its manner of use, is the sole resp o nsi bility of the us e r.
P r i n ted in the U.S.A.
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