Watts Canal Rehabilitation
Santa Cruz, Bolivia
International Senior Design
In August 2006, a group of International Senior Design (ISD) students
from Michigan Technological University traveled to Santa Cruz, Bolivia
to volunteer engineering services for Santa Cruz’s 10th District.
The city of Santa Cruz is divided up into 16 districts with the
10th District situated in the southwest part of the city. UV 125
and UV 126 neighborhoods within District 10 experience flooding
during the 4 month rainy season due to storm-water overflow from
a “curichi”, or swamp, and subsequent flooding from
that swamp’s lone earthen drainage canal, Carmelo Watts Canal.
Carmelo Watts Canal is an important link in the storm-water drainage
system of Santa Cruz since it collects water from the curichi and
the surrounding neighborhoods and deposits it into the 6th Ring
canal, which then continues on to deposit the water the Pirai River
and out of the city. Watts Engineering was appointed by District
10 officials to provide engineering solutions to these flooding
(Click to enlarge)
Impermeable surfaces such as steel roofs and roads create high storm-water
sectional area of current canal is not large enough to adequately
drain storm-water runoff and curichi overflow from a significant
storm causing flooding conditions for homes and roads adjacent to
sediment deposition in canal impede flow
the canal is classified as poorly graded sand with silt, implying
poor drainage properties
Soil sampling and analysis
Visual site inspection
performed to determine the topographic characteristics of the land
over the course of the 6000 ft long Carmelo Watts Canal.
were taken from the invert of the Carmelo Watts Canal and a "Soil
Classifying Geotechnical Gauge" was used to visually classify
the collected soils.
Close proximity of security walls and buildings,
roads, walking paths, street lamp posts and soccer fields
Location of these structures does not permit the
alignment of Carmelo Watts Canal to be moved
Elevation constraints present at additional canal
feeding into Watts Canal and at 6th Ring Canal
Rational Method used to model flow
Watershed area determined from published data
Design storm consisted of a 10 year, 4 hour storm
Resulting peak runoff flow used for canal design
1. Earthen canal
2. Concrete Canal
An earthen canal excavated to adequate capacity was first considered
Relatively low initial cost of construction
cycle costs than lined canals due to high maintenance costs of regularly
clearing sediment and debris.
required cross section of an earthen canal
Watts Engineering dismissed this design alternative because the
required land area is not available to construct an earthen canal
large enough to accommodate peak storm-water flows
required cross section of a concrete canal
Engineering chose to recommend a design for a concrete canal.
W.E. Observed concrete lined canals throughout the city of Santa
Cruz, therefore a concrete lined canal was considered as a second
design option. The design was completed based on an assumption
that the design presented in a 2005 ISD report by EMT Engineering
for a 6th Ring Canal renovation will be completed.
Can be designed
large enough to accommodate peak storm-water flows, therefore preventing
for more efficient maintenance practices compared to an earthen
a sustainable link in the storm-water drainage system in District
10 for future projects
high construction cost
dependant on the completion of 6th Ring design (or equivalent)
Watts Engineering recommends these steps be implemented in order
to maintain proper function of the newly constructed canal.
- Clear gabions, steel grates or grilles, and sediment
control devices of collected sediment at least once per year
- Clear the interior of the canal of deposited
sediment including weep holes at least one time per year
- Clear curb-side inlets three times per year
- Inspect the canal slab and overall structure
at least once every 5 years and complete necessary structural
- Grade roadways adjacent to canal at least two
times per year
- Take measures to strongly discourage littering
Watts Engineering recommends that the client construct design option
#2 calling for a concrete lined canal over the entire length of
Carmelo Watts Canal. The concrete lined canal design will most effectively
address the concerns given by the client during the on-site field
investigation in August 2006. Watts Engineering also feels that
this design option is in the best interest of the client in terms
of safety and sustainability.
The approximate cost to construct a concrete canal is $864,000.
The scheduled duration of construction is 416 total working days
and occurring over three seasons (April 1st through October 30th).
The city must implement an effective maintenance plan in order to
prevent sedimentation and littering within the canal detrimental
to its function.
Construction of the designed concrete lined canal will benefit local
residents and government because the direct and indirect impacts
of current flooding will significantly decrease or disappear. This
will improve conditions in the area for residents and reduce the
possibility of disease from stagnant flood waters.