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LOS ANGELES LEGACY

National Ready Mixed Concrete Co. parks near epicenter of a southern California building boom

Mood best cropA demographic shift driving development of arts, cultural and entertainment venues, along with high-rise residential buildings, will help Los Angeles shed the perception that its downtown is an afterthought amid southern California’s sprawl of highly livable communities and business or tourist destinations. Between 2019 and the Los Angeles-hosted 2028 Olympic Games, the downtown area stands to see a crop of new buildings exceeding 300 feet, including handful in the 700- to 1,000-ft. height league. The building boom coincides with developers and engineers increasingly receptive to seismic exposure-grade, structural concrete cast with high performance mixes that exhibit superior strength and modulus of elasticity properties.

Prospects for high-rise and more conventional development tied to the Olympics are reflected in a jaw-dropping plant National Ready Mixed Concrete Co. opened in October 2018 on a brownfield site just beyond the southern edge of downtown. The twin alley, transit mixed operation is built for 400-plus yd./hour output and prodigious material storage and transfer: 1,100 tons of cement stored in two, five-compartment silos and 5,000 tons of aggregate in three conveyor- and tunnel-fed bins. Sand and gravel unloaded in three grizzlies is belted at up to 750 tons/hour along 12 conveyors bearing on more than 1,500 linear feet of deep truss galvanized supports.

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PHOTOS: Hugh Hunter for National Ready Mix (aerial, dump trains); Concrete Products (mixer alleys)
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Vernon plant site prep and construction spanned January-August 2018. National Ready Mix sited the operation to ensure a typical delivery window in the 30-minute range for downtown Los Angeles high-rise building orders. The producer opted for a dual-lane, transit mixed design of a level manufacturer and dealer, Concrete Equipment Co. and DHE Inc., rarely quote.
East best crop

Twin Con-E-Co batch plants combine for 1,100 tons of cementitious materials, split between two silos engineered with five compartments each; and, aggregate bins containing 375 tons of up to eight grades of material. Feeding the bins are three aggregate bunkers totaling at least 5,000 tons of live storage. Twin 1,500-ton bunkers holding sand and ¾-in. gravel flank two four-compartment, 1,000-ton bunkers dedicated to 1-in. and specialty aggregates.
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Binder versatility is the order of the day at Vernon. Twin, 545-ton silos for the dual alley plant have are divided into five different compartments, three representing 25 percent each, the other two 12.5 percent. Shed plates in both silos ease cleaning during material change out. Tankers stage at one of two lanes serving each mixer truck alley, and transfer powder through 5-in. tubes at rates of 25-28 tons in 40-45 minutes. Silos gravity drop material directly into weigh batchers. PHOTO: Hugh Hunter for National Ready Mix

“We can recharge materials at rates faster than we can batch them, and run at full production for multiple days or finish a major pour with the plant full of materials, ready for the next day,” says National Ready Mix President Steve Lode. “This plant gives us the ability to deliver large volumes of high quality concrete at a rate most ready mixed producers are not able to achieve. We can handle the one off specialty aggregate, specialty cementitious material order without having to shut down and drain bins to resume normal production. The plant has the unique capacity to house and batch 10 different materials at any one time. That means loading a 6,000-psi mix order side by side with a mix requiring 15,000-psi design strength and not missing a beat.”

“This plant offers maximum versatility in material handling and batching capacities, cement and aggregate storage, the speed at which we can weigh things up, and four scales weighing cementitious materials simultaneously,” he adds. “It is over-designed by traditional batch plant standards, but meets what is really called for in the Los Angeles market.”

The new National Ready Mix flagship plant is located in Los Angeles-bordering Vernon, about three to four miles from most downtown construction sites. They will call for the occasional 10,000-yd.-plus or more mat foundation schedule, and more frequent pours in the 2,000 yd. range—routine duty for a day at Vernon.

“The plant can handle ready mixed concrete volumes for high-rise building contracts without logistical problems often encountered when having to schedule raw material replenishment during the middle of a pour,” notes National Ready Mix Director of Operations Sam Hild. “We have to be able to store enough cement and aggregate to cover major orders, then replenish in off hours when the traffic for tanker and dump trucks is lightest. The major focus for the plant was on having the most amount of storage and throughput capacity we could build on limited real estate.”

Vernon is the company’s 11th plant and fills a remaining void in a service area running 50 to 60 miles north-south, 20 to 30 miles east-west. It is in the middle of seven sites on the north-south axis, each within range of Interstate 5—the route to the Lebec mill of National Ready Mix sister operation, National Cement Company of California. The Vernon ready mixed operation is best situated for central Los Angeles business, but can also deliver to sites in an active, but challenging 10- to 15-square-mile area to the west. Considering land values and neighbors encountered in that area—between downtown Los Angeles and the Pacific Ocean—prospects for any new ready mixed production capacity are unlikely in the foreseeable future.

ONE FOR THE AGES

The National Ready Mix Mega Plant is built on an L-shaped parcel in an industrial zone along Interstate 10, separating downtown and south-central Los Angeles. It operates alongside truck terminals, dry goods warehouses, wholesale food distribution facilities, and a metals service center.

National Ready Mix and principal plant supplier, DHE Inc. of Tracy, Calif., mapped the Vernon material handling and storage scheme plus tanker, bottom dump and mixer truck routing on the elongated portion of the site, measuring about 200 x 500 ft. “After three or four months, we came up with the design and configuration to match material storage, variety and flexibility National Ready Mix would need to build and maintain market share,” says DHE’s Scott Humphrey. “In my experience, this is what we call a legacy batch plant; we see one delivered about every 40 to 50 years. This plant should run for generations.”

Water i

Water ii

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Process water captured in mixer truck washout area and from nearby leftover mix ribboning pad is settled in four stages (middle), then pumped to a larger pit adjacent to a washdown station (top) in front—to drivers’ left. Settled water from both areas is tapped for subsequent truck cleaning and batch water. National Ready Mix addressed storm water capture and significant recycling opportunity with construction of a 50,000-gal. storage tank built below the washdown station.
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The Vernon office building lies between a 60-ft. west entry and 40-ft. east exit gate. It houses batch operator stations and a spacious break room designed for an overload of drivers accompanying a plant geared to volume placements. National Ready Mix uses Jonel Archer Batch plant control and Command Alkon Integra dispatching platforms. With routine and major contracts kicking in this year, the next steps at Vernon entail build out of a shop, mixer parking and service area to east of the main plant and truck route—the leg of the L-shaped site.
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East extension

Tracking raw

Vernon site conditions required capping of contaminated soils. That dovetailed crews’ elevating much of the plot an average of 5 feet to create aggregate handling infrastructure, mixer-charging alleys with 14 to 15 feet of clearance, and a massive stormwater storage vessel below a monolithic, 10-in. thick concrete pavement running to the property lines. Plant construction consumed nearly 10,000 yd. of concrete for pavements, foundations and above-ground structures.

In contrast to many high volume urban ready mixed operations with central mixed only or dual wet-dry alleys, the Vernon plant is strictly transit mixed. The choice of dry versus wet reflects the type of orders National Ready Mix anticipates; quality control levels proved in sister transit mixed plants; predictability of truck routing, typically 30 minutes, to downtown construction sites; and, the management team’s concerns over maintenance, labor and energy costs incurred in central mixed plants.

The Vernon site has access only along the 200-ft. front elevation, 26th Street, prompting placement of 60-ft. and 40-ft. gates on the west and east sides of a new two-level office and driver break room building. Trucks enter the larger and exit the smaller gates. Dumps are routed to a three-lane ramp with grizzlies feeding three storage bunkers. Cement tanker and mixer trucks traffic grade-level pavement paralleling the ramp. Tankers travel a perimeter route around the rear of the plant, and unload at one of four lanes (two east, two west) sandwiching the mixer charging alleys. Returning mixer trucks ribbon leftover concrete on a pad across from a four-section process water weir, with settled water piped to a larger open pit in front. All process water is recycled in plant and fleet operations, or in concrete orders—a widely adopted practice in southern California public and private work.

The plant equipment footprint above the pavement consumes less than a quarter of the site. Concrete Equipment Co., represented on the West Coast by DHE, had to assemble the structure in two phases due to the size limitations of its Blair, Neb., facility. Between Con-E-Co and the DHE shop, plant delivery entailed nearly 100 truckloads, as bins, silos, columns, conveyor supports and smaller components combined for 800-plus tons. Seismic design detailing and related building code requirements prompted specification of some of the largest steel beams available in the U.S.; most notably, 30-ft. members supporting the largest aggregate bins weigh 285 lbs./foot.

MATERIAL MATTERS

National Ready Mix dedicates a sizable percentage of Vernon aggregate storage capacity to a premium sand & gravel well suited to a market where developers are going vertical with building plans and high performance concrete is seeing much traction. The sand & gravel is sourced from Eagle Rock Aggregates Inc., which has begun importing fine and coarse grades from a Vancouver Island glacial deposit. (Note this month’s companion report, “Stiff Competition,” page 66.)

“Ready mixed concrete in our market is no longer some universal commodity that can be delivered in the same manner by all producers and batch plants of yesteryear,” observes National Ready Mix Vice President of Sales Chris Heilmann. “Los Angeles Department of Building and Safety codes have seen revisions in recent years requiring significant advancements in our product, boosting the performance and strength of cast-in-place concrete. The code and current specifications we’re seeing require a combination of materials, not always local, and a batching facility that has the capacity to stock materials meeting new specifications. The Vernon plant is the best equipped ready mixed operation in Los Angeles to supply high volumes of specialty aggregate and cementitious material mixes.”

Early-fall trial production of high performance and conventional concrete mixes enabled National Ready Mix to begin commercial deliveries from Vernon in October; ease into a manageable schedule the remainder of year; and, confidently approach major production days (> 2,000 yd.) certain in the first half of 2019. Sam Hild and his Operations team are anxious to see how far they can push their new iron crown jewel. “We anticipate reaching close to 450 yards per hour and sustaining that rate as large pours require,” he affirms. “We have plants where you might be able to do 300 yards an hour for three or four hours, but then at some point they run out of material and have to wait while bins and silos are replenished. We are able to operate Vernon at maximum capacity for any amount of time one or multiple pours would require.”

“We think what we’ll be able to provide here for customers is better than anybody in the market,” adds National Cement Company of California President Steve Wise. “We’re able to bring them the production capacity for normal or volume work, and offer a variety of mix designs very quickly throughout the day—all from a plant right near the center of major building activity in Los Angeles.”


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Aggregate management at National Ready Mix Vernon turns on the Jonel Archer Batch platform and its Material Distribution System.
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Orca b

Orca c

The 1,500-ton west bunker is dedicated to the premium Orca 1-in. gravel, while companion ½-in. gravel and washed sand are stored in a four-compartment, 1,000-ton steel bunker adjacent to the larger storage structure—a mass of reinforced concrete with a five-gate, 100-ft. tunnel to transfer material to batch plant bin-charging belts. The tunnel forming crew sloped the floor for drainage to the process water collection pit.
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PHOTOS: National Ready Mix; Concrete Products