EHST 2361 Surveying Locations & Elevations of Ground Water Monitoring Wells Purpose: This lab will acquaint you with a method for plotting ground water monitoring well (GWMW) relative locations and determining the relative elevations of the tops of GWMWs. The data obtained will provide you information needed to create a ground water table gradient map at the area of the surveyed wells. Identifying up gradient and down gradient wells is important to sampling order. Items to consider: The precision equipment used in this lab is expensive and easily damaged. Handle it carefully at all times. The LT6-900 Level-Transit should be stored in its carrying case at all times when not actually being used, and whenever it is moved from location to location. Given the number of you in the lab, do not wait to be asked to perform a task. VOLUNTEER! It is your responsibility to understand and be able to perform all of the tasks involved with this lab. ASK QUESTIONS! Carefully consider how different weather/site conditions might affect the way you perform the tasks in this lab. Especially think about how obstructions will affect the tripod locations that you might choose. When you are finished with task 19), consider how repeating tasks 3) through 13) from a third location might affect your confidence in the GWMW location map you ve plotted. Tasks: 1) Carefully read General Description Meridian LT6-900 Level-Transit (attached). Disregard the instructions for the L6-20 Level, we are using the LT6-900. Ask questions to clarify anything you don t understand. 2) Proceed to the parking lot (closest to the corner of Richmond and Harvard Roads) with the level, tripod, elevation rod, steel tape, writing utensils, and field notebooks. 1
3) Erect the tripod near the southwest corner curb of the parking lot. Attach the level. Hang the plumb bob as per the instructions, and mark the plumb bob location with nail & tape. Level the instrument as per the instructions. This is the location of Reference Point #1 (RF#1). ONCE THE INSTRUMENT IS LEVELED, DO NOT BUMP OR DISTURB THE TRIPOD UNTIL ALL MEASURMENTS ARE COMPLETED. IF THE TRIPOD IS DISTURBED, YOU MUST START OVER! 4) For our purposes, the elevation of the eyepiece is arbitrarily set at 1200. 5) Unscrew the bolts and remove the protective lids covering the three GWMWs. Remove the padlocks and the protective caps. Set all aside in plain view so they aren t accidentally lost. Note any pressure release or unusual conditions in your field notebook. 6) In your field notebook, draw a rough sketch of the parking lot with the approximate locations of the three wells. Number the wells #1, #2 and #3. Be sure to include a north arrow. Make notes of field conditions and any other pertinent information. 7) Extend the elevation rod one section and set it near the southeast corner curb of the parking lot, holding it as vertical as possible. With help, locate each of monitoring wells. Make sure there is nothing obstructing your view of the monitoring wells from this new location. If so, relocate the elevation rod until your view of the wells is unobstructed. NOTE THE UNIT OF MEASURE USED ON THE ROD. 8) Gently rotate the level to point in the direction of the rod. Sighting through the eyepiece, continue to rotate until the vertical crosshair lines up with the center of the rod. ROTATE THE HORIZONTAL CIRCLE. SET THE HORIZONTAL CIRCLE AT ZERO TO COINCIDE WITH THE VERNIER ZERO. Note that the 360 horizontal circle used to obtain degree measures is divided into four quadrants. This must be taken into account any time the level is moved from one quadrant to another in order to map the next feature or GWMW. It will be necessary to add or subtract degrees to obtain the correct angle from the reference point. 9) Place a nail and tape marker at the exact location of the center of the rod. This is the location of Reference Point #2 (RF#2). Use the steel tape measure to measure the distance from RF#1 to RF#2 and record in your notes. NOTE THE UNIT OF MEASURE USED ON THE STEEL TAPE. An example data table is provided on the last page of this Lab. You may duplicate this table in your field notes. 2
10) Select one of the three GWMWs. Move the rod to the first one of the GWMWs you plan to map. Place the rod so that it is resting on the top of the plastic well casing, holding it as vertical as possible. 11) Gently rotate the level to point in the direction of the rod. Sighting through the eyepiece, continue to rotate until the vertical crosshair lines up with the center of the rod. In your field notes, note the height mark on the rod corresponding to the horizontal crosshair in the telescope. Then note the reading on the graduated circle and vernier. 12) In your field notebook, make the following notation: SW corner to Well #[ ] = [reading in degrees and minutes]. Rod Height at Well #[ ] from SW corner = [reading from elevation pole]. 13) Repeat tasks 10), 11) and 12) for the other two GWMWs. 14) Remove the instrument from the tripod and return it to its carrying case. Move the equipment to RF #2. Set up the level above the nail and tape mark. Use the plumb bob to make sure the level is directly above the mark. Repeat tasks 3) through 13) (except determination of rod height) from the southeast corner. 3
15) [ALTERNATE TASK: If obstructions prevent you from obtaining at least one elevation reading of any GWMW, repeat tasks 3) through 12) from a location near the sidewalk at the top of the rise north of the parking lot. Why?] 16) Re-secure the three GWMWs. 17) Measure the distance from the plumb bob mark at the southwest corner curb to the plumb bob mark at the southeast corner curb using the steel tape. In your field notebook, make the following notation: Distance from RF #1 to RF #2 = [distance in feet and inches]. (See graphic #3) This is the length of the reference line. 18) Remove the instrument from the tripod and return it to its carrying case. Proceed to EEC-169 with all equipment. 19) In the lab room, plot the relative locations of the three GWMWs to scale using your field notebook data, graph paper, a pencil, a ruler and a protractor. Choose an appropriate scale. Keep this map for now; you ll need it for Lab #3. 4
Example Data Table: MW#1 ANGLE FROM RF#1 to MW ROD HEIGHT FROM RF#1 ELEVATION TOP OF CASING FROM RF#1 ANGLE FROM RF#2 to MW Depth to Groundwater Groundwater Elevation MW#2 MW#3 Length of reference line: Note: Depth to Groundwater and Groundwater Elevation will be determined using data collected during the groundwater sampling lab Scoring: EHST 2361 - Monitoring Well Survey Map and Groundwater Flow Determination Required Score Minimum Requirements Elements (points possible) Location of wells Each well is identified on the map in correct position (4) Water table slope Elevation of water table indicated using contour lines (1 foot contour interval or other as appropriate) (4) Arrows on map depict groundwater flow direction; Groundwater flow alternatively, you may use narrative to describe flow direction direction (4) Top of casing; Neatly listed in a table depth to (2) groundwater Measured angles Neatly listed in a table (2) North arrow, key, Present and accurately oriented scale (2) Neatness Handwritten numbers and letters are legible, readable; erasures are complete (2) Total score (20) 5
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