Building principles: drama in real life ... as seen from the engineer's seat!

For many years, Boys' Life magazine ran a regular column that chronicled the heroism of certain Scouts who had been in the right place and time, maintained a cool head, and saved the day for an unfortunate catastrophe victim. In a small way, we often have the opportunity to help clients avert financial, project, or legal disasters in their own right. Recently, we wrapped up a pretty simple project in which the extra effort the owner invested at the outset paid great dividends. In this column, we'll look at how we set the project up, some of the logistical issues we encountered, and how we resolved those problems. In the next issue, we'll look at what happened after the quotes were received and how we made the plan a reality.

The Background

In August, the operations manager for this particular camp asked us to make a site visit during the camp season to look at their sewage sand filter and offer an assessment. Their thirty-year-old treatment system is typical of many camps we serve--septic tanks around camp settle out solids and grease from the wastewater, and gravity piping carries the liquid to a siphon house where it is released in batches to the surface of a large bed of sand. The liquid percolates through the sand where its toxicity is reduced by organisms living there. The treated liquid is collected in drain pipes beneath the sand where it flows to tanks for aeration, disinfection, and discharge to a small stream nearby.

When we arrived, we saw that the liquid was not passing through the sand, but was ponding on the surface of the filter bed. Regular, specific chemical analysis is required by the state Department of Environmental Protection (DEP). Not surprisingly, the tests revealed that the system was not delivering the level of treatment required by the permit because of the sand bed failure. DEP required completed repairs before the camp would be permitted to operate the system next year. As soon as the campers left, we began planning.

The Issues

Although the system troubles were pretty easy to spot, the scope of the project quickly grew heads like the mythical Hydra. The first set of hurdles was to query agencies that might be issuing permits or have any sort of oversight role.

Department of Environmental Protection

The existing system had to be compared to the current configuration and operation regulations, since it was possible that upgrades might be required as part of this repair. DEP had to determine whether a repair permit would be required. They concluded that this was a maintenance activity, and a repair permit would not be necessary. The state regulations require not less than twenty-four inches of filter sand. In the course of operation and time, though, the sand condenses and is lost through the piping, and regular raking activities remove sand from the surface as well. Our typical design is for thirty inches of filter sand to account for these operational losses.

Additionally, current design standards require that an impervious liner be installed beneath the drain pipes to prevent the liquid from seeping into the ground. We were able to show DEP that, for this particular project, a liner was not needed, saving the owner a substantial expense. Lastly, the sand filter itself is 240-feet long and 60-feet wide, and the filter media in place was designed to be 2-feet thick, so 28,800 cubic feet (1,033 cubic yards) of sand would have to be carefully removed (not disturbing or damaging the drain piping just beneath the stone layer) and deposited somewhere. The owner had a place to stockpile it, but DEP had to approve the "disposal" site and had pretty specific instructions on what would be allowed to happen to that mountain of material.

Local Municipality 

The township had to be consulted to determine if a construction permit (and associated fees) would be required. To the camp's advantage, the township did not have a fee assigned to this sort of project, and they didn't think that they could have one assigned before our project would be complete. So no fee was involved there either, although we now had notified them that work would be going on.

Department of Transportation (DoT)

Lastly, the DoT had to be advised that there would be heavy construction equipment delivering material to the site, and there would be discussion about bonding. (Since we waited until we had selected a contractor to talk to DoT, we'll come back to this next issue....)

What's the Scope of the Project?

What Will It Really Take to Get It Done?

Having found a place to stockpile the old stuff, we needed to determine whether the collection pipes beneath the sand were clear and properly draining the area. There were twenty-four, 4-inch diameter pipes that were completely buried beneath the sand. Camp staff uncovered the upstream end of each pipe and ran a stiff steel tape from one end to the other. Any pipe that didn't allow the tape to pass freely to the collector pipe at the far end was tagged for replacement. It turned out that there were six. While they were uncovered, we added some fittings to extend the pipes to the surface so that they could be checked without uncovering them in the future.

We would need 60 feet by 240 feet by 2 1/2 feet--or 36,000 cubic feet (1,333 cubic yards)--of filter media. Assuming that a heavy duty dump truck can hold about 18 1/2 cubic yards, we estimated that 72 truckloads would be required. That's a lot of material and many trucks.

Oddly enough, the most difficult step in this part of the project was finding sand filter media. For the filter to operate properly, the size range of individual grains of sand (the gradation) needs to be nearly the same size to provide air space between the particles to support the necessary biology. This is exactly the opposite of what most quarries are accustomed to producing--a broad range of sizes of grains for making concrete and asphalt. An extensive search of quarries within hundreds of miles (no exaggeration) revealed no supply whatsoever. Eventually, a specialty sand supplier was located 230 miles from the site. The trucking issue suddenly loomed even larger.

Who Shall Bell the Cat?

So far, we knew what work was required, and we could estimate the volumes and costs for the material and components of the project. The next question to be answered was whether the camp would try to tackle this with its own staff or hire a contractor. There was some discussion about the fact that this was a really simple project all around. There was no equipment to be ordered--only sand and pipe. The camp owned a backhoe and a couple of trucks. They usually laid off most of the grounds staff for the winter, and the camp's caretaker was a very competent individual in every respect. It sounded like a perfect setup!

But the camp operations manager looked at more than these most obvious issues. He considered the opportunity costs of the work of replacing the routine maintenance and other planned repairs that normally are done in the winter, the liability of reconstructing the wastewater treatment system in house, and the monumental effort to coordinate material deliveries from a site 230 miles away. The decision was made to find a competent contractor to get the work done. The lesson here is that even simple projects may not be appropriate for the most capable in-house staff. There are, after all, only so many hours in a day, and as winter approached, those hours got shorter very quickly.

OK, Now What?

To set up bid documents, the next step was to determine how much involvement the staff would have in the project--allowing the balance of the work to be contracted. It was decided that the camp would use their otherwise laid-off helper to serve as the project observer--receiving the sand and watching the contractor work. This presence would be very important if there had been any sort of accident. Since we had located the source of filter material--and knowing how difficult it had been to find--we made arrangements for the camp to purchase the material directly from the supplier.

At this point, we made an important distinction. Since the contractor would be responsible for setting and maintaining the construction schedule, the bid would provide for arranging and coordinating trucking. Because the supplier certified that there was enough material in stock for the whole job, the contractor would now have no claim against the owner if material arrived too fast or not fast enough. At the same time, the camp was taking responsibility for verifying that the media would meet the DEP set requirements.

The Bid Period

Rather than rely on a contractor's interpretation or understanding of what we wanted done, we prepared simple bid documents consisting of plans, a quotation form, and contract general conditions. Based on filed drawings of the original installation, we drew a plan showing the bidders what to expect--and what the final installation should look like. Using field measurements and the file drawings, we estimated the amount of sand that had to be removed and stockpiled (in cubic yards); the length of pipe which would have to be replaced (in linear feet); the amount of stone required to bed the pipe (in cubic yards); and then the amount of sand that was to be purchased by the owner but spread by the contractor (in cubic yards).

The quotation documents were drafted using the quantities and units of measurement we estimated earlier. The quotations were set up in a chart format (see page 10). This method provides outstanding flexibility when administering the contract and allows for changes in quantities of materials to be installed at set prices. It also permits line-by-line comparisons of each component of the work between the quotes. There were other items in the agreement that have been omitted for brevity.

Several local contractors were invited to a site meeting to look at the project, ask questions, and talk about the scope of work and the bid documents. Representatives from four companies came. In that forum, we were able to keep the process on an even footing, since everyone could hear the questions and the responses. In addition, it let each contractor know against whom they would be competing. One of the attendees decided to not quote the project at all, but we received three proposals.

To get to this point required three months of diligent effort--with frequent phone calls to regulators, material sources, and the owner. The camp is governed by a board and given that the cost estimate for the work was in the hundreds of thousands of dollars, they were rightfully deliberate and cautious. Unfortunately, the time spent preparing the project to go under contract also used the very best ninety days of weather that we could expect before spring.

Chart

Rick Stryker is a professional engineer with Camp Facilities Consulting providing study, design, permitting, and construction consultation services to the camp and conference center community. Camp personnel may contact him at 570-296-2765 or by e-mail at [e-mail].