My company, Access Builders, often works with banks on foreclosed properties. These bank-owned properties typically just need to be cleaned up and put back on the market, but sometimes we have to deal with an unfinished home that a builder forfeited before receiving a certificate of occupancy.

On one such project in an outer suburb of Minneapolis, we had to address a serious grading problem. The bank owned two duplexes built next to one another on a considerable slope, and the original site plan called for a swale to be dug between the two buildings to divert runoff from the higher unit out to the street.

Unfortunately, the builder never followed through with the grading. By the time we got involved, the driveways were in, the sod was laid, and the landscaping was 90 percent complete. In addition, there were several large trees designated for preservation that would be destroyed if the swale were dug in accordance with the plan.

Finding the Right Sub

I met at the site with the city engineer and our excavator. The engineer insisted that the runoff had to be diverted. It was our excavator who first brought up the possibility of having a directional-boring company pull a drain tile through. Although this seemed like an unlikely solution to me at the time — I assumed that only municipalities, utilities, and other deep-pocketed entities could afford directional boring (also known as trenchless excavation) — the engineer agreed that it was an option, as long as he approved the specifications.

Weighing our options. Our excavator determined that digging the swale to the original spec would require about 100 feet of digging and the removal of up to 400 yards of soil. His estimate was $5,500, not including replacing sod or building the required retaining walls. In all, we figured, it would cost about $8,500 to finish the swale as originally intended — plus any fines for removing protected trees and the costs for replacing them.

Before seeking other estimates, we checked with the engineer who drew the original drainage plan. He also felt that horizontal boring could work and told us that generating the numbers and redrawing the survey would cost less than $1,000. So far, so good.

But after a dozen phone calls to various companies and two on-site consultations, my doubts began growing. I was getting bids anywhere from $4,000 to $6,000, not including material or engineering costs. It was looking as though directional boring would not save us much money after all.

Irrigation, but in reverse. As luck would have it, our longtime irrigation contractor gave us the lead we needed. I hadn’t realized it, but irrigation companies often sub out directional-boring jobs when their supply lines need to traverse driveways and other obstacles. When I mentioned the holdup on this project, he gave me the phone number of Goldade Ditching, a company accustomed to working on small projects like ours. The person I spoke with there readily gave me a rough estimate over the phone, which came in well below the numbers we’d been hearing. Excluding materials, Goldade priced the job at $14 per linear foot to pull a 4-inch pipe, $16 per foot to pull a 6-inch pipe, and $20 per foot to pull an 8-inch pipe. I said I didn’t think a pipe as large as 8 inches would be necessary, but it turned out I was wrong.

The Final Plan

We submitted a revised plan to the city engineer calling for 100 feet of 6-inch HDPE (high-density polyethylene) pipe running the same path where the swale was supposed to be, with a single 12-inch by 12-inch catch basin on the low spot between the two properties. According to our engineer, that system would handle the water from a 50-year storm event. That seemed reasonable to us, since even if such a storm occurred there was no danger the water would flood into either house — excess water would simply run across the yard of the lower house before reaching the street.

Revising the revision. The plan was rejected. The city engineer wanted the system to be designed for a 100-year storm instead, which has a 1 percent likelihood of taking place any given year. Although that’s a typical standard for dams, levees, and storm sewers, it seemed like a lot to expect of a yard drain. But because I’ve found that maintaining a good relationship with city officials usually pays off in the long run, I agreed to try again. Our second plan was for two 12-inch by 12-inch catch basins and a fusible 8-inch HDPE drain tile; it was approved.

Not your father’s drainpipe. Fusible HDPE drain tile is heavy-duty stuff that has little in common with ordinary corrugated drain tile. The 8-inch pipe we needed has walls nearly an inch thick, which is necessary to allow it to withstand the tremendous pressure of being pulled through the soil. It came in 50-foot lengths that cost $400 apiece, and even after I had them cut in half at the plumbing supplier so I could bring them to the site on my ladder rack, each 25-footer weighed 200 pounds. While I was at the supplier, I also picked up the fusing machine needed to weld the sections together.