Data available in the appendixes include site locations and hydrologic characteristics of peat and individual tables for data collected on September 22-October 2, 1997; November 10, 1997; November 19-20, 1997; December 11-17, 1997; June 3-6, 1998; July 20-23, 1998; September 20-October 5, 1999; and October 25-28, 1999
Orem, W. H.; Harvey, J.. W.; Spiker, E. C.
Orem, William H.; Harvey. Judson W.; Spiker, Elliot C.
Krupa, Steven L.; Gefvert, Cynthia J.; Choi, Jungyill; Mooney, Robert H.; Giddings, Jefferson B.
Krupa, Steven L.; Gefvert, Cynthia; Mooney, Robert H.; Choi, Jungyill; King, Susan A.; Giddings, Jefferson B.
Harvey, J. W.
Harvey, Judson W.
Newlin, J. T.; Krest, J. M.; Choi, J.; Nemeth, E. A.; Krupa, S. L.
Krupa, S. L.; Krest, J. M.
The elevations for vertical control points near wells were transferred to well top control points.
All wells and horizontal measuring points were surveyed by global positioning (GPS). Vertical measuring points on land surface, staff gauges, and well tops were determined by leveling.
Thirty-five monitoring wells were emplaced in the Surficial aquifer at depths ranging from 15 feet to 180 feet below the wetland sediment surface. Of those wells, eleven were drilled on levees surrounding ENR or WCA-2A to more efficiently utilize full size drilling rigs to obtain core material from the entire depth of the aquifer and to emplace the deep wells that were needed for hydrologic monitoring. Twenty-four monitoring wells were drilled at interior sites in the wetlands requiring the use of a portable tripod-drilling rig in WCA-2A and a specialized floating barge in ENR.
To prevent cross contamination from soil/debris between drilling sites, all equipment was steam cleaned at a staging area located at least 2000 feet from the well drilling locations. The contractor was required to bring in city water via the drill rig or support truck for all operations. The city water was tested for trace levels of mercury prior to any drilling activity/ No surface water was used for any cleaning or drilling.
Boreholes were drilled and monitoring wells emplaced on levees by contractors. All borehole wells were drilled using the mud-rotary drilling method. The eight deep wells (greater than 95 feet below land surface) were drilled first to allow geophysical logging to be completed. The geophysical logging allowed onsite evaluation of lithological data and aided in eh placement of screen intervals if the monitoring wells. The boreholes at these sites were geological sampled using either standard penetration testing and standard coring or wirleline coring. Only the seven deepest boreholes were selected for geophysical logging.
The 2-inch diameter wells at ENR and S10-C levee-based sites consisted of a two-foot section on 0.010-inch PVC screen and ten and five-foot sections pf 2-inch PVS riser pipe. Care was taken to prevent contamination during the drilling process. Wells and piezometers at the six interior ENR sites were installed by a contractor using a floating drilling barge. All samples were collected by the wireline coring method.
Wells at the six interior WCA-2A sites were installed by USGS staff utilizing their portable tripod drilling rig with rotary coring capabilities. Surface water was used as the drilling fluid for this operation and was pumped down the annular space via hydraulic pumps. No drilling muds were used at the WCA-2A sites. As soon as possible after well emplacement, wells were developed by pumping at high flow rates for one hour or until all turbidity had cleared, whichever took longer.
Unconsolidated sediment samples were obtains from Split-spoon samples or Wireline samples at five sites in the ENR and at one site located at the S-10C site in WCA-2A. A small amount of unconsolidated sand material was extracted from the Standard Penetration Test (SPT) liner and continuous cores at two-foot intervals for sieve analysis to identify different depositional environments within the aquifer.
All samples of limestone obtained from the coring and drilling operations were reviewed and checked for competence. Only samples collected from the six deep boreholes that were geophysically logged were considered for further analysis. Samples were analyzed to determine the porosity and hydraulic conductivity of the selected limestones, percent (by weight), of potassium, concentration of uranium and thorium, and total gamma count.
Dried and sieved sand fractions were returned to the SFWMD in Ziploc freezer bags, marked with the boring number, sample number, sieved fraction and site location. Each soil boring was boxed. Each fraction of dry-sieved sand was sorted through to identify complete shells or shell fragments. Each soil boring was assigned a Munsell color chart number. Once the shells were separated out for each two-foot interval, a hydrogeologist identified them.
SFWMD staff used a software program to estimate the hydraulic conductivity of each sieve sample. The program used ten equations and the grain-size statistics to calculate hydraulic conductivity. The ten resulting values were the arithmetically averaged to improve the reliability of the estimate of hydraulic conductivity.
Hydraulic conductivity was also determined by field drawdown tests. The drawdown tests were scheduled only after the wells had been fully developed and after at least one round of water quality sampling. The same test method was used at each site.
See OFR 00-483 for a more complete description of the field methods and laboratory analysis of the data.
U.S. Department of the Interior, U.S. Geological Survey
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