Project Profile: A Natural Water Park in Boise

Nov. 3, 2016

Located in the heart of Idaho’s capital city, Boise River Park and Esther Simplot Park are destined to become a recreational paradise for Boise residents and visitors. Phase I of the Boise River Park was completed in 2012, which attracts hikers, kayakers, fisherman, and other water enthusiasts looking to cool off and experience the energy and beauty of the river. This section of the Boise River is a tributary of the Snake River, which runs approximately 75 miles (120 kilometers) long, and drains part of the Sawtooth Range northeast of Boise.

In 2012, the City of Boise—along with sponsors and other city supporters—began work on a renovation and construction of the natural waterpark: Phase II of the Boise River Park. Additionally, the adjacent Esther Simplot Park—a 55-acre site encompassing 17 acres of ponds suitable for fishing, wading, and swimming—began construction early 2015. For this portion of the park initiative, three neighboring ponds will be connected to the river and a sandy beachfront will be built, which, in total, involves moving approximately 400,000 cubic yards of dirt. The new park will provide elements that will reduce flood risk to property and protect river water from pollution, blending seamlessly with all the other park elements.

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Once complete, Phase II of Boise River Park will include the construction of in-river drops, chutes, natural slaloms, jetties, and instream boulders to maximize the recreational experience on this stretch of the river and will work in concert with the existing Phase I River Park facilities and the adjacent Esther Simplot. The existing irrigation diversion structure will be replaced with recreation friendly facilities that will improve the flood conveyance capability of the river, while still providing the necessary irrigation water delivery demands.

The Esther Simplot Park, when complete, will provide expanded ponds and a connecting channel. Natural and paved pathways will weave through grassy areas and across bridges. Recreational features will include pond beach access for fishing and boats, natural playground features (logs, boulders, etc.), picnic shelters, ADA accessible pathways, improved trail surfacing, and relocation of the Boise River Greenbelt to provide improved access to the overall site.

Design-Build firm McMillen Jacobs Associates was selected to design and construction the Boise River Park Phase II and Esther Simplot Park projects. The company has a track record of successfully delivering complex water resources and heavy civil projects using its design-build model, which includes in-house environmental, engineering, and construction capabilities.

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To tackle the excavation portion of this project Andrew Pharis, onsite assistant project manager for McMillen Jacobs, consulted with equipment and technology partner SITECH Western States. In terms of heavy equipment, McMillen Jacobs has allocated three articulated trucks, two loaders, one dozer, three excavators, and one compactor for this project.

Looking for superior grading production, McMillen Jacobs equipped one dozer and an excavator with the Trimble GCS900 Grade Control System. The team also adopted Trimble’s base station solution SPS855 and the Trimble SCS900 Site Controller Software to collect survey points and share data in the field.

SITECH Western States assisted with loading the digital designs on to the Trimble GCS900 Grade Control System on the heavy equipment. SCS900 software allowed the team to perform positioning tasks such as checking grade and elevations in “real-time.” This information is utilized to calculate volumes and troubleshoot challenges on the fly. Pharis explains that one of the primary reasons McMillen Jacobs selected the GNSS grade control system from Trimble is that it offered operators the ability to grade with increased accuracy and eliminated the need for a full-time survey crew. On most jobs of this size and scale, setting stringlines to cut grade would require having a full-time survey crew onsite.

“With GPS and machine control, the survey cost associated with this project was approximately a third of what it would typically be,” says Pharis. “Instead of having an employee shooting elevations and checking stakes from within a 35-foot-deep trench, we were able to have our excavation operators provide these same elevation checks from within the cab. This allows us to avoid survey crews having to work around the concrete, rock and rebar located in the trench. The beautiful part is now our excavation operators can ensure greater accuracy and efficiency.”

For mass excavation on the Esther Simplot Park, digital design data was loaded in the dozers and excavator. Using automatic guidance inside the cab, operators can excavate out earth and old concrete to construct a trench around Friendship Island all while ensuring the desired designed slope, elevation and grade are met. Together, these elements will route the water properly. The system uses GPS to compare the cutting edge position to the digital site plan and then signals the operator to raise or lower the blade to achieve the design requirements. This allows for increased grading productivity and accuracy, and because each pass of the blade is more productive, rework is essentially eliminated because the earthwork is moved correctly the first time.

Because they can work more efficiently, McMillen Jacobs estimates that the crews are able to move approximately 6,000 cubic yards of dirt per day. They are also meeting tolerances for the sand beach of +/- 1 inch—more accurately than ever before. Pharis estimates grading productivity is up approximately 40% because the excavation operators have access to the digital design plans in the cab. The operators can also excavate in several locations across the job site due to the fact that they do not need to reset lines or wait for surveyors to measure and set before beginning work.

“It’s incredible because we can meet our tolerances in one pass,” says Pharis. “We can successfully rough grade an area and hit our targets and then move to the next location.”

McMillen Jacobs is also using the Trimble SPS855 base station solution, and Trimble TSC3 data collectors to provide positioning information to operators running a small excavator on the project site. With this equipment, the team is trenching utility and irrigation lines and following the digital design plan, all with a single surveyor onsite.

“With Trimble GPS and machine guidance for the excavation scope of work we were able to provide not only extreme accuracy but streamline the work activity to push this landmark project ahead.”