Block of Fire

Dec. 11, 2006

Originally Denver’s very first city block, historic Larimer Square is now the epitome of high-energy urban revitalization, offering trendy, eclectic shopping, hip nightlife and some of the finest restaurants around. Day and night this place hops. Larimer Square is a success on many levels due in part to its very involved business owners and merchants. So when the issue of repaving and improvement work was raised, concerns were high. But this is a story with a happy ending—a very happy ending.

Squared away

Originally Denver’s very first city block, historic Larimer Square is now the epitome of high-energy urban revitalization, offering trendy, eclectic shopping, hip nightlife and some of the finest restaurants around. Day and night this place hops. Larimer Square is a success on many levels due in part to its very involved business owners and merchants. So when the issue of repaving and improvement work was raised, concerns were high. But this is a story with a happy ending—a very happy ending.

Squared away

With Larimer’s existing asphalt pavement severely deteriorated and badly rutted due to heavy bus traffic and poor subgrade, and with poor drainage due to sunken curb and gutter, the reconstruction was a necessity. In addition, there were non-ADA-compliant access ramps at the 14th and 15th Street intersections that needed to be replaced.

Work began in earnest in 2003 when the city and county of Denver began the planning and design of improvements for Larimer Street from 14th to 17th. Reconstruction of the 14th to 15th block (Larimer Square proper) would occur first and entail complete curb-and-gutter replacement, asphalt removal and complete subgrade restoration and replacement with 11-in.-thick concrete pavement and the complete reconstruction of corner areas at each intersection with the installation of ADA-compliant access ramps and truncated dome pavers.

In late 2005, the city and county of Denver implemented the city’s Integrated Construction Program (IC), a citywide compilation of capital- improvement projects executed under one umbrella contract with the Parsons Corp. The Larimer Square project was the first of the IC projects to be implemented, and as such it allowed the city to select the best-qualified contractor—a contractor with proven success with concrete reconstruction projects in heavy pedestrian and trafficked downtown areas.

Concrete Works of Colorado is such a contractor. With award-winning work on jobs in other high-profile locations with equally tight budgets and committed time frames, Concrete Works took on the challenge. Public meetings began in late 2005 and continued into early 2006. Their staff provided the concerned business community with examples of similar concrete paving projects such as the beautifully executed Broadway reconstruction in downtown Boulder and the very successful Grand Avenue reconstruction in downtown Glenwood Springs. Both projects were American Concrete Pavement Association award winners in 2005 and 2006. But this project was not going to be easy by any means. It was an extensive amount of work with a very tight timeline: five weeks. Deciding the start of construction was not going to be easy, either.

Avoiding a crowd

One of the first considerations was the holiday shopping season and how best to avoid it. Construction had to be scheduled after the Christmas retail season during a good weather window and yet before the start of spring activities that bring huge crowds down Larimer, such as Colorado Rockies baseball. The warmer weather also would bring patio seating for restaurants. The list went on.

There were numerous considerations, all with one goal: minimal impact on the local businesses. Throw Denver’s highly unpredictable winter weather into the mix and the timeline became very difficult. Basically, construction had to occur in late February or early March. It became exceedingly clear that concrete reconstruction was the only option.

There also were more challenges to consider. The necessary utility coordination had to work around and protect a very shallow water main and high-pressure gas main. Utilities work would include replacing a high-pressure steam line vault in addition to the installation of private gas line service along both sides of Larimer Square to provide gas to all of the historic gaslights. Questions from the merchants lingered: Would the work be completed in a timely manner and in good fashion? The materials for the job were determined: 11-in.-thick concrete pavement with 4,200-psi concrete, the standard city of Denver concrete paving mix, No. 6 epoxy-coated tie bars on all longitudinal joints and 1-in.-diam. smooth dowel bar baskets on all transverse joints, sealed with self-leveling silicone sealant. The final concrete pavement surface would be finished with an artificial turf drag texture.

The specifications were defined: The street width measured 38 ft from face-of-curb to face-of-curb, with two 11-ft travel lanes and two 6-ft parking lanes for the 400-ft-block length. There would be a 12-in. recycled concrete base course placed on reconditioned subgrade beneath the new concrete pavement. All four corners at 14th and at 15th would be reconstructed with architecturally scored colored concrete and ADA-compliant access ramps, with 2-ft x 2-ft precast, pretensioned high-strength concrete truncated doom tiles placed in the ramps. With the planning and design of the project complete, they crossed their fingers for good weather.

Lastly, and critical to the success of this project, was the final approval and buy-in by the merchants and the city’s traffic engineer to allow complete street closure during construction, providing the contractor with full and unimpeded access to the work area.

And they’re off

Construction started with the removal of the existing asphalt pavement, curb and gutter and the sidewalk area at 7 a.m. Monday morning on March 6. By mid-afternoon on the same day, all existing pavement and curb and gutter had been removed, and the excavation for the 12 in. of recycled concrete base began.

The next day, the base material was placed under the new curb and gutter, and the gutter was poured on both sides of Larimer the entire length of the block. The roadway excavation and base placement continued at a steady pace. On Wednesday, the base placement was completed with final trimming and the string line was set for the GOMACO slipform concrete paver. In the meantime, the project became a point of interest for shoppers and those enjoying a meal on Larimer as they marveled at the progress of the work.

Thursday, March 9, brought the slipform paving of the center 22 ft of concrete pavement. As the paving machine work was finishing, the 6-ft parking lanes were poured by pumping concrete from each end of the street and filling the gaps. By the end of the day Thursday, the entire street, including curb and gutter, was complete—a mere four days into the construction. At this point the merchants were awestruck, especially since the crews worked through not one, but two snowstorms that hit the area in the first four days.

Even the smallest details were noted. At one point during construction, Concrete Works suggested that all tree grate frames and concrete curbing be replaced. In total, 20 tree grate frames were removed and replaced, adding to the aesthetic value of the project.

During the ongoing construction, crews worked diligently to maintain pedestrian access, and as a result the four corners had to be reconstructed at separate times. The reconstruction of the corner areas was still completed by Wednesday, March 15.

On Thursday, March 16, less than 10 days after the start of construction, the final clean and striping occurred and a ribbon-cutting celebration was held in the mid-afternoon. The commitment to the original construction time frame of five weeks was reduced to a mere 10 days. Merchants were now ecstatic, and the praise began to flow.

Stu Williams, the city of Denver’s director of engineering, was duly impressed. “The city and the Larimer Square business community could not have been happier with the overwhelming success of the Larimer Square project. The city, Parsons, Concrete Works of Colorado and the Larimer Square Management team worked exceedingly well together and completed the project in a time frame and with a level of quality that exceeded all expectations. This concrete reconstruction and the manner in which it was completed has set the standard for future street reconstructions in downtown Denver.”

City and county of Denver Project Manager Dennis Ohlrogge wrote: “We decided early on that concrete was the pavement of choice for this reconstruction project. The existing asphalt pavement was terribly rutted and required continual, disruptive maintenance. The use of concrete pavement also allowed us to accommodate very shallow utilities and most importantly allowed us to construct the project during the winter in March, which was determined to be the least-impactive time for the Larimer Square business community. Kudos to Concrete Works for a job well done.”

But it was the letter sent to Williams at the city, and signed by every merchant on Larimer Square, that said it best: “At this date, we all thought that Larimer Square would still be undergoing its street repaving project. Fortunately, because of the phenomenal job orchestrated by the city and county of Denver, Parsons and Concrete Works, you delivered this project way ahead of schedule—a mere 10-day closure. You all worked together in an unprecedented way, and all of the tenants of Larimer Square cannot thank you enough for your diligence.

“In addition to exceeding our expectation on the schedule, the attention to detail and the regard that you showed on this project are worthy of great praise. It was evident that every person working on this project wanted everything done at the highest level of quality. Such integrity in workmanship is all the more notable in the maintenance of a historic district such as ours. Your attention to detail was evident in every step of this process; you even minimized the impact to the tenants and visitors of Larimer Square by maintaining a clean and safe worksite.

“We especially want to thank the crew of Concrete Works who dedicated more than 16 hours each day to ensure the timeliness and pursuit of perfection for this project. The hard work displayed by each employee was the talk of the Square—when not left speechless by the progress. We wish to extend our greatest appreciation to you and all those involved in this new addition to Larimer Square.”

Substantial improvements combined with the complete repaving of a bustling shopping and entertainment district in the heart of Denver in just 10 days? That’s a very happy ending indeed.

About The Author: Brasher is general manager of Concrete Works of Colorado.

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