Geoysynthetics August/September 2023 - 15

Lake Forest reservoir
relining and floating cover
By Brian Fraser, MBA, Douglas Hilts, P.E., and Robert Emmons
G
eosynthetic floating covers provide a highly sustainable and
economical method of protecting and treating fresh and
potable water. They are designed to protect fresh water from environmental
contamination while eliminating water losses due to
evaporation. Case in point is the Seattle Public Utilities, Lake Forest
potable water storage reservoir. The reservoir was first built in 1962
as an open-top, concrete-lined 60-million-gallon (227-million-l)
containment facility for potable water storage.
In 2002, the reservoir underwent multiple modifications and
improvements, which included a 28 foot (8.5 m) vertical cast-inplace
reinforced concrete center divider wall and the installation of
a geomembrane liner and floating cover. With the divider wall, the
reservoir was separated into two independent operating cells, each
approximately 288 feet wide by 671 feet long by 24 feet deep (87.8
m × 204.5 m × 7.3 m). The reservoir operates as a potable drinking
water storage facility and provides emergency water supply. A
45-mil (1.143-mm) reinforced polypropylene geomembrane liner
and floating cover were installed in 2002 and were experiencing
problems that required replacement.
In May 2021, phase 1 construction began on the new replacement
geomembrane liner and floating cover system for the east cell
of the Lake Forest reservoir and was completed in September 2021.
Phase 2 included the installation of a new geomembrane liner and
floating cover system on the west cell. This construction was completed
September 2022.
Project challenges
The construction challenges included developing a revised floating
cover design and installation plan to address the issues with
the 28 foot (8.5 m) vertical divider wall. To address the vertical
wall configuration and shape of the reservoir, the design
PROJECT HIGHLIGHTS
LAKE FOREST RELINING
AND FLOATING COVER
LOCATION
Lake Forest Park, Wash.
OWNER
Seattle Public Utilities
CONTRACTOR
Layfield USA
CONSTRUCTION COMPANY
Layfield USA
ENGINEERS
Hilts Consulting Group
GEOSYNTHETIC PRODUCT
CSPE
GEOSYNTHETIC MANUFACTURER
Burke Industries
Brian Fraser is vice president of Layfield
Geosynthetics in Lakeside, Calif.
Doug Hilts is president of Hilts
Consulting Group in Yorba Linda, Calif.
Robert Emmons is a business
development manager for Layfield USA
in Renton, Wash.
All figures courtesy of Seattle Public Utilities.
GeosyntheticsMagazine.com
15

http://www.GeosyntheticsMagazine.com

Geoysynthetics August/September 2023

Table of Contents for the Digital Edition of Geoysynthetics August/September 2023

Geoysynthetics August/September 2023 - Cover1
Geoysynthetics August/September 2023 - Cover2
Geoysynthetics August/September 2023 - 1
Geoysynthetics August/September 2023 - 2
Geoysynthetics August/September 2023 - 3
Geoysynthetics August/September 2023 - 4
Geoysynthetics August/September 2023 - 5
Geoysynthetics August/September 2023 - 6
Geoysynthetics August/September 2023 - 7
Geoysynthetics August/September 2023 - 8
Geoysynthetics August/September 2023 - 9
Geoysynthetics August/September 2023 - 10
Geoysynthetics August/September 2023 - 11
Geoysynthetics August/September 2023 - 12
Geoysynthetics August/September 2023 - 13
Geoysynthetics August/September 2023 - 14
Geoysynthetics August/September 2023 - 15
Geoysynthetics August/September 2023 - 16
Geoysynthetics August/September 2023 - 17
Geoysynthetics August/September 2023 - 18
Geoysynthetics August/September 2023 - 19
Geoysynthetics August/September 2023 - 20
Geoysynthetics August/September 2023 - 21
Geoysynthetics August/September 2023 - 22
Geoysynthetics August/September 2023 - 23
Geoysynthetics August/September 2023 - 24
Geoysynthetics August/September 2023 - 25
Geoysynthetics August/September 2023 - 26
Geoysynthetics August/September 2023 - 27
Geoysynthetics August/September 2023 - 28
Geoysynthetics August/September 2023 - 29
Geoysynthetics August/September 2023 - 30
Geoysynthetics August/September 2023 - 31
Geoysynthetics August/September 2023 - 32
Geoysynthetics August/September 2023 - 33
Geoysynthetics August/September 2023 - 34
Geoysynthetics August/September 2023 - 35
Geoysynthetics August/September 2023 - 36
Geoysynthetics August/September 2023 - 37
Geoysynthetics August/September 2023 - 38
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Geoysynthetics August/September 2023 - 40
Geoysynthetics August/September 2023 - 41
Geoysynthetics August/September 2023 - 42
Geoysynthetics August/September 2023 - 43
Geoysynthetics August/September 2023 - 44
Geoysynthetics August/September 2023 - Cover3
Geoysynthetics August/September 2023 - Cover4
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