purcc 2012 - University of the Pacific

Poster Session Abstracts
engineering courses to produce a design in
compliance with specifications and rules outlined
by the National Student Steel Bridge
Competition committee. Specifications dictated
dimensional limits, construction restraints, and
judging criteria. The bridge was judged by a
panel of practicing engineers who evaluated
performance categories including stiffness,
aesthetics, construction, and sustainability.
In the design phase, several bridge designs were
modeled in RISA-3D structural simulation
software to evaluate structural performance
under an applied load of 2500 pounds. A
selection was made based on deflection and
weight performance. Upon selection of the
optimal design, shop drawings were rendered in
AutoCAD software to determine material
quantities. Following fundraising, the team
purchased the necessary tools and materials to
begin the fabrication process. Students cut,
welded and drilled steel parts while
incorporating innovative dovetail connections to
allow for rapid construction with minimal
deflections. These design features allowed the
students to construct the bridge in approximately
27 minutes. Loading the bridge with 2500
pounds yielded 1.1 inches of vertical deflection,
and a 50-pound lateral pull produced less than
0.5 inches of deflection. The strong structural
performance was echoed by a fierce aesthetic
presence, consisting of an orange truss, marked
with black stripes mimicking that of a tiger’s
back.
An Assessment of the Total Phosphorous
Mass Balance Using a Modified
Persulfate Digestion Method
Matthew Ebia
Faculty Mentor: William Stringellow
Chelsea Spier (graduate student)
California ranks first in the nation in municipal
solid waste, sewage sludge, dairy manure, and
food processing waste generation. This waste has
undeveloped potential biogas generation capacity
estimated at 600 Megawatts. Utilizing these
wastes to produce biogas for energy production
could help California meet state renewable
energy goals and greenhouse gas emission
reduction targets. The Ecological Engineering
Research Program (EERP) is working with
Fiscalini Farms, a California dairy, to develop
best available control technology for biogas
combined heat and power systems and collect
system performance data for future use to
advance the science, technology, and market
penetration in California. A mass balance of
nitrogen, sulfur, carbon, salts, and solids is being
developed. Samples collected as part of this
mass balance include a mixture of slurry and
solids. Slurry samples have been measured for
total phosphorous (TP) since the beginning of
the project using a modified persulfate digestion
followed by an ascorbic acid reaction, which
allows for colorimetric determination of TP. For
my part of this project, I am developing a new
method for TP determination on solid samples
based on standard methods because the previous
method was determined to be insufficient for
many sample types. Once this method is
developed all archived solid samples will be
measured and TP will be included as part of the
mass balance. The mass balance is critical to the
long term sustainability of the system because
nearly all wastes entering the system remain on
site and are ultimately applied to the fields as
fertilizers.
Solving the low dissolved oxygen problem
by understanding the sources and fate of
different nitrogen species entering in the
San Joaquin River Estuary
Ernest A. Garcia
Faculty Mentor: William Stringfellow
Stockton’s deepwater ship channel (DWSC) has
been suffering from low dissolved oxygen for
decades, especially in dry water years. The
Ecological Engineering Research Program
(EERP) has been the lead science agency on the
Dissolved Oxygen (DO) Total Maximum Daily
Load (TMDL) project since 2005. The purpose
of this project is to collect and analyze data on
the sources of nutrients, phytoplankton and
oxygen-consuming materials in the San Joaquin
River (SJR) estuary, the upstream SJR, and
upstream tributaries to support the development
of an estuary model. This model is needed by the
Central Valley Regional Water Quality Control
Board (Regional Board) to provide modeling
tools, scientific data and other information to
support management actions that will be taken
by the Regional Board and stakeholders to
resolve the low DO problems in Stockton’s
DWSC. For my part in this project, I have been
responsible for measuring ammonia, nitrate, and
total nitrogen in samples collected in 2011 as
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