As you take the book off the shelf, a paper falls out and falls on the ground. You pick it up and look closely at it. It appears to be a survey map of a community, with a variety of markings on it. The markings appear to denote the location of wells within the community.
The book the map fell out of appears to be one of Aunt Darcy’s field journals. The journal contains handwritten information, some diagrams of well construction, and copies of newspaper clippings from a variety of countries, including Spain, Nigeria, South Africa, among others.
Skimming the articles, you quickly learn that many countries seem to be plagued by a proliferation of people illegally drilling boreholes. These wells, which are constructed without regulatory approval and oversight, are a risk to public health, to the environment, and to water security. Poorly sited and constructed wells pose a health risk, as they may contain contaminated water. Further, damaged or poorly designed casing, a lack of protective cover, and insufficient protection around the well may allow pollution to infiltrate into the aquifer. In addition, improper construction often leads to premature failure of the well. Illegal wells also harm efforts to sustainably manage groundwater. Improper spacing of wells may cause groundwater pumping to interfere with other wells or to intercept nearby surface waters. Excessive illegal use can also lead to over pumping of groundwater, which can lead to land subsidence, degradation of groundwater fed wetlands, and drying up of springs.
The diagrams of proper well construction are fairly interesting, you had never thought about what the inside of a well looked like before.
You remember Aunt Darcy had just come back from a trip during which she had spent days doing field work. The map must be part of the survey she was working on. Reading the journal, you see that Aunt Darcy appears to have been visiting every property in the community. For each property, she had written notes about whether the property had a borehole, the state of its construction, and the results of a water quality test from it. The identification numbers for each borehole match those on the map, though oddly some are numerical and some are alphabetical. Perhaps this somehow related to the letter you found on the table, addressed to Euler. That letter spoke of illegal boreholes and something about connecting the dots.