The opening of the Hamilton Crossings shopping center is still at least two years away in Lower Macungie Township.

If approved, the project will bring the much-anticipated first Costco Wholesale Club store to the Lehigh Valley. Target will be the other anchor store in Hamilton Crossings, which will have a total of 25-30 stores.

The project reaches a milestone in the long approval process at 7 p.m. Tuesday, when its developers seek numerous variances from the Lower Macungie Zoning Hearing Board.

More than just another shopping center, Hamilton Crossings is being promoted as a town center, a community gathering place and a gateway to Lower Macungie Township.

Lower Macungie has been looking to have the property developed for a long time, said Jeremy Fogel, spokesman for the development team. While it is not centrally located in the township, he said it is in the middle of Lower Macungie’s commercial corridor.

Hamilton Crossings developers promise upgraded aesthetic appeal and amenities similar to those at the Promenade Shops at Saucon Valley in Upper Saucon Township.

The project is unusual because the developers are asking Lower Macungie Township, East Penn School District and Lehigh County to pick up part of the tab, which totals more than $115 million, by agreeing to take less property tax revenue from the shopping center for up to 20 years.

The developers maintain they won’t be able to build the shopping center without that help and warn no one else will be able to build on that site, largely because a major man-made environmental problem is beneath the surface of the property.

The shopping center is proposed on 63 acres of meadows along both sides of Krocks Road, between Hamilton Boulevard and the Route 222 bypass. Krocks Road will become the main entrance for Hamilton Crossings.

The developers said the total property, including about 10 acres north of Route 222 that will be used for storm water drainage, now only generates about $10,000 a year in total property tax revenues for the township, school district and county. If the shopping center is built, they say that total will increase to up to $1.4 million a year.

While Fogel could not provide a breakdown, most of that $10,000 goes to the school district, which has the highest property taxes, and none goes to the township, which hasn’t collected property taxes from its homes and business for many years and won’t do so in 2013.

The Hamilton Crossings development team -- Tim Harrison of Staten Island, N.Y., and The Goldenberg Group of Blue Bell, Montgomery County – has agreements of sale to buy the entire 73 acres.

All but seven acres of the land is owned by the Allentown Catholic Diocese, which planned to have it become part of a cemetery before it was sliced up by construction of the bypass and the relocated Krocks Road.

The development faces a major complication. In the late 19th Century, iron ore was mined on the site. Left behind were hundreds of thousands of tons of waste material, called mine wash.

That non-toxic mine wash has been described as mud, slurry and quicksand, with the consistency of toothpaste or pancake batter.  The soupy material was dumped into open mining pits after iron ore had been removed. Those pits eventually were covered with soil and some of the property has been farmed.

The problem is that buildings cannot be erected over the unstable mine wash deposits, which extend as deep as 26 feet beneath the surface.  Fogel said any building constructed over them would settle significantly.

"Mine wash is prevalent across the site,” said Fogel. “We found it all over the place.”

The southern portion of the property is especially wet, according to the developers.

They estimate 50,000 dump truck loads of mine wash will have to be dug up, dried and stabilized by being blended with limestone and soil cement. Even after that mix is put back into the ground and compacted, buildings will not be erected on it

Sara Pandl, the township’s director of planning and community development, said the location of proposed buildings had to be changed when site borings were done and the mine wash deposits were discovered. She added even mine wash deposits beneath parking areas must be dug out, to make sure those areas are stable.

If that mine wash is not remediated, said Fogel, “nothing can go on this site.”

Power lines also cross the property. Pandl said only parking lots can be constructed beneath those power lines, not buildings.

The Hamilton Crossings project was first proposed to the township in 2009 with just two big stores – a Target and a Lowes. But Lowes later decided it was not building any new stores, said Pandl. She said later BJs and ShopRite became interested, adding ShopRite still is interested, and Costco replaced BJs.

The closest Costco stores to the Lehigh Valley are near Montgomeryville and Pottstown. “Costco!” declared a resident at a recent township meeting. “Make the whole thing Costco!”

Fogel said Costco and Target will own their stores and parking areas and the development team will own the rest of the property.