A Sewer System from Scratch
An extensive long-term project to build a gravity-feed sewer system is placing Lake Havasu City, AZ, in a good position to protect the environment while accommodating future growth.
Prior to 1964, Lake Havasu City did not exist. There was a 45-mile-long lake where the Colorado River backed up behind Parker Dam, but the remote reservoir was largely unknown to residents of Arizona and California. Most of the land near the lake belonged to the Mohave and Chemehuevi, tribes that make up the Colorado River Indian Tribes.
Robert McCulloch bought 3,500 acres of land alongside the lake in 1964 and set out to build a planned community catering primarily to winter visitors and retirees from the Midwest and Northeast. In 1978, the town's population reached a point where it made sense to incorporate.
Over the next 20 years, Lake Havasu City grew dramatically. College students from all over the West discovered the city and congregated each year for Spring Break festivities. Expensive vacation homes began sprouting along the lake and in the hills east of downtown Lake Havasu. The city's future was looking bright, and the population continued to grow.
Then, in the mid 1990s, higher than acceptable levels of total coliforms turned up in a water samples taken at several of the popular beaches in town. Mark Clark, the city's assistant public works director, said that discovery was quickly followed by more bad news.
“ADEQ came to town and installed several monitoring wells up and down the shoreline,” Clark explained. “They found high levels of nitrate in the well water and imposed a 1-mile ban on installation of conventional septic systems near the lake.”
The beach closures drew national attention, and city officials realized they needed to take strong action to protect the lake and the recreation industry that provided the community's lifeblood.
At that point, Lake Havasu City had nearly 45,000 full-time residents and hundreds of vacation homes. A sewer system in the downtown area and a pair of small wastewater treatment plants provided service for less than 20 percent of the city. Nearly all the homes and several businesses were on septic tanks, and the high concentration of septic systems had overloaded the soil's capacity to deal with the waste.
A little checking revealed that Lake Havasu City was, by far, the largest community in the United States without a city-wide sewer system. That had to change.
“We hired Burns and McDonnell out of Kansas City in 1997 to help us create a wastewater treatment master plan,” Clark recalled. “We explored the possibility of constructing a small-diameter gravity system that would leave the septic tanks in place and capture wastewater for treatment.” After some study and somewhat heated public comments, the citizens asked for the option to vote for a conventional gravity sewer system, even though that option required significantly more investment.
Planners estimated the system that needed to be built would cost $463 million. They swallowed hard and took their proposal to the voters in a bond election in 2001. Despite the daunting price tag and the prospect of seemingly endless road construction, voters approved the plan by more than 70 percent.
The original master plan called for a 20-year program, with the possibility of shortening the work to 10 years. An 11-year project, with the city subdivided into several project areas, was the final outcome due to the difficulty in getting this huge project started. The areas closest to the lake were targeted first, with construction then working its way up the hill to the east of town. Future growth was factored in, and sewer mains were specified to handle far more flow than would come from existing structures and lots.
“Most of our project areas have 2,000 to 3,000 connections,” said Ryan Kanzleiter. He is deputy program manager for AMEC, the company that has served as program manager, design and construction administration consultant for the program since 2005. “The areas are developed but with sporadic vacant lots. Every vacant lot gets a lateral up to the property line.”
The original work plan broke the project into 11 one-year phases that were, in turn, divided into three partitions, and each partition was bid separately. The size of the overall project attracts attention from construction companies all over the country, and bidding has been competitive. Through the first seven years, the project has had nearly a dozen contractors work at least one partition, but a handful of contractors have become regulars in the mix.
Scope Presents Challenges
Kanzleiter said the greatest challenge AMEC and the city face is simply the scope of the project. “Your typical wastewater treatment expansion ties in to an existing system. In a city the size of Lake Havasu City or larger, most expansions are in place before homes and businesses are built. The building lots have to be adapted to the system. Here, we have to adapt to existing structures that were built without consideration of how they might connect to a future sewer line.
“Coordinating everything adds to the challenge. When you add 2,000 connections, you have to be sure the pumping stations and treatment plants have the capacity to handle the increased flow.”
Mark Clark credits AMEC with doing an outstanding job on collection design and project coordination. He pointed out that typical wastewater expansion projects in developed areas don't concern themselves with connections to individual properties. Lateral lines go to the property boundary. The property owner has to handle details like septic tank decommissioning and connection to the system.
“On our project, AMEC has responsibility for working with the property owners and helping them through the process,” Clark said. “They help make sure the paperwork gets done on schedule, and they work closely with city staff to administer grants and financial assistance for property owners who don't have the $2,000 treatment capacity fee. They've done a fantastic job of communicating and working with our citizens.
“Their designers have had to find ways to make a gravity system work on streets where home elevations are all over the board. My house is 25 feet above the roadway, and the house across the street is a little below street level. How do you design a sewer line to fit both of those conditions?”
Kanzleiter said part of the solution requires taking the mainlines down well below grade where necessary. Some lines are 24 feet below street level in places.
That can create problems for contractors like Wagner Construction. Based in International Falls, MN, Wagner has become one of the regulars on the project. Wagner Project Manager Matt Guerton said the company has been working various portions of the Lake Havasu City project for three years now. In December, his crews started work on what is shaping up to be the most difficult digging they have faced so far.
Wagner's first few blocks of the new phase are in a neighborhood of expensive hillside homes with nice lake views. During an interview in early December, a nearby excavator was straining to hit depth on a trench.
“The rock structure on some of these streets is extremely hard,” Guerton said. “It's caliche, but then you get into a lot of sand pockets. This dig right now is the hardest I've seen so far here. We have a Komatsu 600 excavator, and it's chewing at 17 feet and barely making it through. Our lateral crews have Komatsu 138s digging 5-foot sub cuts, and they're barely making it through.
“We have a 1.5-yard ripper bucket for the 600 and a 2.5-yard trenching bucket. We scratch with the ripping bucket to loosen up the material, then switch to the trenching bucket to pull out whatever excess the ripping bucket leaves. We could bring in something bigger, but then you get into width restrictions. We have a long-stick 345 Cat excavator that can dig at 24 feet. We'd like to use it more, but if it gets too hard, we have to use the 600.”
Dirt and rocks removed from the trenches are run across a screen. The screen separates fine material and sends it to a stockpile to be used as bedding material for the pipe. Coarse material is used to finish filling the trench after the pipe is safely covered with fines.
Wagner's fleet consists of Komatsu and Caterpillar equipment. Guerton says the company has picked up several pieces of good equipment at Ritchie Brothers auctions since coming toArizona.
“It's a great way to keep your fleet up to date,” he stated. “Obviously service is one of our main issues, and having good-looking equipment is important. The general public doesn't just see the pipes you're putting in the ground. They see your men, your machinery and your trucks. We like to have a good face on the company.”
Seven years into construction, the project is more than a year ahead of schedule and well under budget. Greg Froslie, assistant public works director and city engineer, gives credit tocity staff.
“Jeremy Abbot, project manager for the city, and his staff have done an outstanding job with managing our consulting engineers and contractors.
“The Arizona Department of Environmental Quality has been extremely helpful and cooperative. Nothing can be done until ADEQ signs off. By rule, we weren't allowed to make any connections until the entire system was built and tested. That didn't sequence well with our contractors. We'd have had our streets torn up the entire time with great inconvenience to the public.
“City staff and ADEQ developed a partial engineer's certificate of completion, and ADEQ's been wonderful. A contractor builds a stretch from manhole to manhole with laterals to the property line. That section is tested through a PECOC process and results are faxed to ADEQ. They do a 24-hour turnaround to review results and approve. Another crew follows the mainline crew to decommission septic tanks, connect homes, restore landscaping, and pave the roads. It's like a big parade going through the neighborhood, and it disrupts the neighborhood for as brief a time as possible.”
The strategy of working quickly with major disruptions for short time periods, rather than minor disruptions for long periods, has been well accepted by the community. It's also knocked one year off the original time estimate and nearly $25 million off the projected project cost. More savings appear likely in the next year.
Getting connections online as quickly as possible is a priority, according to Froslie.
“Our flows are significantly lower than projected,” he said. “That translates to lower revenue from user fees. The solution is to get as many people connected as quickly as possible, so more users are sharing the cost.”
Making a long-term project of this scope work smoothly on so many levels is an accomplishment. The program would not be as successful as it is without the cooperation of several different entities working towards a common goal of constructing a centralized sewer system in Lake Havasu City.
Greg Froslie doesn't hesitate to state, “We're very proud of what we've accomplished here. It hasn't been easy, but I think we got it right.”