GeoLab 11

GEO 109L – Earth, Environment, & Society Lab Lab Exercise 11 – Groundwater Introduction Next to the oceans and ice caps, groundwater is the largest water reservoir on Earth. We rely on our groundwater resources for individual water access as well as municipal, industrial, and agricultural water supply on a large scale. Because of the constant and increasing demands, it is essential for individuals and local, state, and federal agencies to work to maintain the quantity and quality of this resource. In this week’s lab we will investigate both the nature of the materials that groundwater moves through as well as how exactly we study this part of the hydrologic cycle that we cannot readily observe (it is underground)! Materials:  Flow Test Materials  Stopwatch  Ruler  Calculator  Pencil Lab Exercise Part 1 – Flow Test In order for scientists and water engineers to understand the speed at which groundwater moves through an aquifer, which ultimately affects the rate at which water can be pumped out and how fast potential contaminates move from a source to other areas of the aquifer, they first must perform tests on well bore samples from the aquifer. These tests, referred to as flow tests, send a certain amount of water through a sample under a set pressure in order to observe how much water can be stored in the material and how fast it moves entirely through the sample. We will recreate a portion of this type of test today in lab. We are going to simplify the test and use open funnels under the force of gravity to drive our flow test. Follow the procedure (green box) and then answer the questions following. Your flow test set up is already set up in the center of your table. You have three sediment (unconsolidated or loose) types. Each funnel holds approximately 100 cm 3 of sediment. You also have a 250 ml beaker with 100 ml of water in it and an empty 100 ml beaker or 250ml beaker with graduated cylinder.  Place the empty 100 ml beaker (or 250 ml beaker) under one of your funnels.  You will complete three flow tests, one at a time. DO NOT START THE FLOW TEST UNTIL YOUR TIMER IS READY .  You will be recording multiple time points during the test. The time it takes for the first water to leave the funnel AND how long it takes until water stops leaving the funnel (all/most of the water has moved through the sample).  Once the timer is ready, start timing and pour the 100 ml of water into the funnel (if the water nears the lip of your funnel, wait until the water level drops to finish adding all the water).  Record your times in the table following . IF YOUR WATER TAKES LONGER THAN 2 MINUTES to move through your sample. Stop your test at 2 minutes and record how much water moved through during that time. Lab 11 | 1 NAME: ____________________ Table # ___

1) RECORD YOUR FLOW TEST RESULTS BELOW 2) Rank your three sediments below in order of highest (a) to lowest (c) permeability. a) b) c) 3) In the table below, write next to each K value (hydraulic conductivity) which sediment type you think best fits. 4) Below is a cross-section (side view) of the Great Miami Buried Valley Aquifer (GMBVA). Dayton and most of Southwest Ohio relies on the GMBVA for the majority of our water needs. This aquifer is composed of a pre- existing (pre-Ice Age) bedrock valley that was filled with loose sediment as the Ice Age glaciers advanced and retreated over 500,000 years. The sediments include Sand, Gravel, and Clay. Determine which of the sediments of the GMBVA are an AQUIFER layer or a CONFINING layer. Sand and Gravel: ______________ Clay: ______________ 2 Sediment Type Time Water First Leaves Funnel (secs) Time Last Water Leaves Funnel (secs) Amount of Water After 2 minutes (ml) Fine Sand Gravel Clay Sediment Type K value gravel 1,000 ft/day Fine sand 100 ft/day clay 1 ft/day