Bill Doelle groans every time he reads a newspaper headline that says “Archeology Find Halts Construction Project.” As the president of Tucson-based Desert Archaeology Inc.—consultant to Pima County on the cultural preservation efforts during the Regional Wastewater Reclamation Department’s $720-millionRegional Optimization Plan—Doelle and his team were just as attentive to the present day needs of construction crews as they were to investigating the past.

Doelle说：“该县已经发展了25年，一种非常标准化的程序，可以评估地面上的内容并在建设进行之前照顾大问题。”

History is literally underfoot everywhere in Tucson, so it’s no wonder that the county and its residents have been so active in protecting and preserving cultural resources since the 1970’s. To date, more than 8,500 archeological and historical sites have been discovered, shedding light on the history of humans that have lived in the area continuously for 12,000 years, according to the皮马县文化资源与历史保护办公室。

但这是在优化计划的扩展期间。废水处理设施是最非凡的发现之一。该发现被称为拉斯卡卡斯（Las Capas），是“迄今为止在北美发现的最早，最复杂，最复杂的农业灌溉系统”，该县历史保护办公室计划经理Loy Neff说。广泛的田地和灌溉沟渠可以追溯到公元前1250年的圣佩德罗时期到公元前750年

该系统是在2008年开始的考古发掘期间发现的，并被评为2009年全球10个最佳发现之一。考古杂志。工作将会继续through 2013 as construction progresses.

内夫说，这些发现对考古学家和历史学家来说是重要的，因为史前人群如何发展以及他们用来生产食品的最终问题（以及与社会组织的变化发生变化）对于理解北美整个史前历史至关重要。

Cultural Excavation

Working long before the planned start date of the plant’s expansion, archeologists began the investigation by digging a series of trenches up to 10 ft deep using a standard 2-ft-wide backhoe bucket. The trenches allowed archeologists to view the various soil layers laid down over millennia by the region’s seasonal flood cycle and choose areas for further investigation.

接下来，挖掘分包商剥离了污垢的顶层，其中包括在现场以前的建筑过程中放置​​了多达5英尺的填充物。

Desert Archaeology then brought in their own skilled backhoe operators, who used specialized 7-ft-wide blades, referred to as “giant trowels.” The operators could pull off as little as a half-centimeter of dirt at a time. “If you work with a backhoe long enough, you get an almost fingertip-like sensitivity in what that metal blade scraping over the ground surface is telling you,” Doelle says.

正是在这段时间里，团队注意到了污垢和图案的差异，表明围绕种植场的堤坝。

Hand excavation was then performed in select areas, such as at housing pits where workers likely lived while tending the fields or maintaining the irrigation system.

All told, the team removed 155,865 cubic meters of dirt and conducted intensive excavations in several areas totaling about 7 acres to a depth of 9 ft, says Jim Vint, Desert Archaeology’s project director.

Four separate irrigation systems were found, rebuilt one on top of the other like a layer cake, separated by major flood events that had covered the previous system with alluvial material up to a foot thick. The fields extend for an estimated 80 to 100 acres, though this may change as more areas open up for investigation.

The primary crop was maize, or corn. Incredibly, archeologists are able to pinpoint individual planting holes for each corn stalk within the fields, due to slight variations in soil color.

The ancient irrigation system met its end with a cataclysmic flood which sealed the system beneath a massive amount of sediment. Bad for the farmers in 750 B.C., but good for archeologists today since the site has been preserved in a way similar to Pompeii’s preservation from a volcanic eruption in Italy, Doelle says.

Keeping a Low Profile

To minimize the impact to construction schedules, Neff gets involved with all county public works projects from the start of planning, working closely to educate on cultural resource compliance rules.

内夫说：“我们越早参与他们的计划，我们就能越能为他们提供帮助，而我们的机会就越少。”“我的目​​标是进入，获取我们需要的信息，做考古，满足合规要求，然后出门，同时不影响施工时间表。到目前为止，我们已经能够在Ina Road做到这一点。”

The archeologists were fully integrated into the construction team at Ina Road, even attending weekly meetings starting with the early stages of pre-planning, Doelle says.

现有工厂的工人不知道脚下有一个虚拟的考古金矿。Vint说：“我每周在工厂为员工提供旅行，这让他们对我们正在做的事情睁开了眼睛。”“他们中的许多人真的很惊讶他们在这个3,000年历史的网站上工作。它改变了他们对他们在哪里工作和历史重要性的看法。”