Laserfiche WebLink
graded, cover-soiled, seeded and mulched in April 2002. The final reclamation project in spring 2002 <br />included the final design construction and riprap installation of the permanent Southeast and Northwest <br />perimeter/diversion ditch segments, above junction of the perimeter ditches with Terrace Drain #3. <br />Perimeter ditch segments below Terrace Drain #3 had been completed in 1994. Final reclamation in <br />2002 included extensive roughening to enhance vegetation establishment, and rock placement for small <br />animal habitat. <br />Pertinent mapping, cross-sections, piezometer monitoring data, compaction data, construction <br />certification, and permanent diversion certifications are included in the bond release application. <br />DMG documented compliance of the lower reclaimed benches and perimeter ditches during a special <br />focus oversight inspection conducted with OSM in August 1997. Extensive slope and ditch <br />measurements were taken, and results were described in the DMG inspection report of August 29, 1997 <br />and report addendum of October 17, 1997. <br />Construction certification for the new segments of the Southeast and Northwest perimeter ditches was <br />included in the 3rd quarter 2002 refuse area P.E. certification by Jim Stover. DMG measurements of <br />various segments of the S.E. and N.W. perimeter ditches (both 1994 and 2002 construction segments) <br />are documented in the Ditch and Channel Measurements section of the Division's inspection report <br />dated April 15, 2003. <br />General configuration of the final graded upper bench slopes and top of pile appeared to be in <br />accordance with the approved design. The top of pile is mildly crowned, with bench outslopes in general <br />conformance with design slope gradients and bench heights. DMG slope measurements documenting <br />compliance are presented in the Refuse Area Slope and Terrace Drain Measurements section of the <br />inspection report dated April 15, 2003. <br />Construction design for CRDA-1 included installation of an underdrain. For a number of years, the only <br />seepage from the underdrain has been in the immediate vicinity of the Southeast Perimeter ditch inlet to <br />Pond 6. At the time of the bond release inspection, soil in this underdrain outlet area was moist, but <br />seepage water was not evident. Documentation concerning installation of the underdrain is described on <br />page 12 of the September 28, 2001 DMG inspection report. In summary, correspondence and inspection <br />reports from the early 1980's indicate that the underdrain was apparently completed and observed to be <br />functional, but the installation was apparently not properly certified by a professional engineer. A notice <br />of violation was issued by DMG in 1993, for the failure to certify underdrain installation. <br />On CRDA-1, the operator monitors water levels at multiple zones within the pile to document <br />conformance with stability analysis assumptions. 30 piezometers on the two lower refuse benches are <br />monitored and water levels are reported quarterly, to ensure that permit specified "critical levels" are not <br />exceeded. The piezometers were installed in 1994, and monitoring conducted since installation has not <br />documented a single exceedance of a critical level (apparent exceedances for PZ #406 in the 2"d and 3r0 <br />quarter of 1998 were determined to be erroneous). There periodically have been problems with <br />monitoring certain of the piezometers (#307 prior to 1997, and additionally #107and #303 since that time) <br />due to occasional constriction or obstruction. For an assessment of this monitoring prior to 1997, refer to <br />the DMG inspection report of 8/29197 (page 2) and addendum of 10/17/97 (page 1). Since that time, <br />restrictions have been reported for #107 three times (4`" qtr. '98, 4tb qtr. 2000, 4`" qtr. 2002), for #303 one <br />time (4`" qtr. '98), and for #307 6 times (4`" qtr. '98, all four quarters of 2000, 2nd qtr. 2001). In the <br />Division's judgement, these occasional monitoring problems with three of the 30 piezometers do not <br />represent a significant flaw in the monitoring program. Monitoring of the problem piezometers has been <br />successful on many occasions and has not indicated a single exceedance. Further, uniformly successful <br />monitoring of the remaining assemblage of 27 piezometers has never indicated an exceedance. Given <br />these facts, the Division has not and is not at this time requesting replacement of any of the occasionally <br />problematic piezometers. Further, no indications of mass instability have been noted in quarterly P.E. <br />inspections, or by the Division during regular monthly inspections or special focus OSM oversight <br />inspections. Only limited minor rill erosion has been observed, and a one time occurrence of minor <br />Phase I Bond Release 15 August 15, 2003 <br />