DRC-2011-001274 - 0901a068801f7988

D^C-2011-00127
Geosyntec'^
consultants
10875 Rancho Bernardo Road
Suite 200
San Diego. CA 92l2j7
PH 858.674.6559
FAX [phone] I
www .geosyntec.com
21 January 2011
David Rupp, P.E.
Division of Radiation Control
Utah Department of Environmental Quality
195 North 1950 West
POBox 144850
Salt Lake City, Utah 84114-4850
Oxnard, CA 93030
Subject: Response to Review of Cell 4B Construction and Request for Information
Cell 4B Construction Quality Assurance Report Addendum
White Mesa Mill - Cell 4B
Bianding, Utah
Dear Mr. Rupp,
Geosyntec Consultants, Inc. (Geosyntec) has prepared this letter on behalf of Denison Mines
(USA) Corp. (DMC) in response to the Utah Department ofEnvironmental Quality, Division of
Radiation Control's (DRC's) Review of Cell 4B Construction and Request for Information dated
20 January 2011. This letter serves as an addendum to the "Cell 4B Construction Quality
Assurance Report, White Mesa Mill, Bianding. Utah" prepared by Geosyntec, dated November
2010. For ease of review, the DRC's comments are summarized below in italics with DMC's
responses following each comment.
1. The Construction Drawings. The originally dated November 2009 Construction
Drawings are mentioned in the report, paragraph 3.2. Several design change
notifications (DCN) are provided in Appendix B. Il appears that revisions of the original
drawings, except for sheets 1 and 6 are included in the subject CQA Report. Please
provide for these missing drawing sheets 1 and 6, as revised for construction, in the
report.
Drawing sheets 1 and 6 were not changed during construction and were therefore not
included as a DCN. Drawing sheets 1 and 6 are included with this letter response as
Attachment 1.
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2. The Slimes Drain Header
a. As discussed last month by telephone, please provide one or more photographs
demonstrating lhal the along the slimes drain header in the SE corner ofthe cell,
lhal Ihe slimes drain header is ballasted continuously on both sides, as request in
the subject DRC Email dated December 14, 2010.
Photographs nos. 1 and 2 in Attacliment 2 show the slimes drain header sandbags. Photo 1 was
taken 13 December 2010. Following receipt of the email request 14 December 2010, additional
sandbags were installed to provide continuous ballasting on 21 December 2010. Photo 2 shows
the installation ofthe sandbags during the 21 December 2010 event. A photograph of the header
is unavailable as approximately 5 feet of precipitation has accumulated in the southeast portion
ofthe cell and is now covered with 8 inches of ice. Removing the water beneath the ice and
subsequently breaking and removing the ice may damage the liner system and is therefore not
recommended.
b. In the subject Geosyntec letter of December 21, 2010. photographs nos. 1 and 2.
show there are IM'O separate sand bag lines crossing over the woven geotextile,
which covers the slimes drain header. Also photograph no. 34 in Appendix A of
the subject CQA Report show sandbags crossing over the woven geotextile
covering Ihe slimes drain access pipe. Il appears these bags may have been
placed lo ballast woven geotextile joints withoul sewing such joints. According to
Ihe subject CQA Plan paragraph 11.7 and the CQA Report, paragraph 6.6.3.3,
the woven geotextile is lo be sewn at all joints. Please provide photographs to
demonstrate lhal these location.'^, including examples of olher woven geotextile
joins, have been sewn in accordance wilh these specifications.
The woven geotextile overlying the nonwoven filter geotextile along the header pipe is designed
to only provide ultra-violet (UV) protection of the underlying nonwoven geotextile. The
underlying nonwoven filter geotextile is designed to act as a filter between the tailings and the
drainage aggregate. The nonwoven geotextile seams are continuously sewn, while the woven
geotextile seams (3 butt seams) are overlapped 12-inches and ballasted with sand bags. The
performance of the woven geotextile is not compromised by the lack of sewn seams.
Furthermore, the woven geotextile seams are in compliance with the Technical Specifications
(Geosyntec, 2009), which state the geotextile shall be overlapped a minimum of 12-inches and
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does not require a sewn seam. Although the CQA Plan (Geosyntec, 2009a) states that all seams
will be overlapped 12-inches and continuously sewn in accordance with the Technical
Specifications, the design intent and the Teclmical Specifications are correct in not requiring the
woven seam to be sewn.
i. Strip Drains
a. Page 7 of Ihe subject CQA Report discusses design change notification (DCN)-
006. It states "This design change modifies the specifications lo allow the
placement of additional sandbags parallel and adjacent lo the existing sand bags
if the underlying strip composite is visible. " Irt contrast, the subject Geosyntec
letter of December 21, 2010. page 3, the fifth paragraph, the first sentence
contains a phrase which states, "...sand bags are no longer placed along the
sides of...bags, which have been rearranged to comply with the coverage and
thickness requirements... "Il appears the inteni of this statement may be lo cancel
DCN-006, i.e. perhaps now there is no parallel and adjacent sand bags lo strip
drains installed on the projeci. However, this statement in Ihe letter may be
interpreted in more than one way. Therefore, verbiage in the current CQA Report,
regarding DCN-006 need to be clarified as lo the preservation of any parallel
sand bag placements adjacent lo strip drain lines.
The intent of DCN-006 was to allow the parallel and adjacent placement of sandbags in the event
the sand bags overlying the strip composite could not be moved (e.g. frozen in place and shape).
DCN-006 is an option for sand bag placement in addition to the original design as shown in
Detail C on Drawing Sheet 6. The sandbags currently in place in Cell 4B were made compliant
with Detail C on Drawing Sheet 6 in December 2010 when warmer weather allowed for the
bags, which were previously frozen in place and shape, to be moved to comply with the original
design. Therefore, although DCN-006 was not used in the final construction of Cell 4B,
modifying or retracting DCN-006 is not necessary.
b. As mentioned in a telephone conversation with you last month, we request a
drawing or manufacturer's catalog cuts, etc., showing the engineer's approved
method, used during this construction, lo change the direction of the slimes strip
drains.
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(1) . There are several locations shown on the original plans requiring the
direction of the strip drains lo change. Please demonstrate the method
used wilh example photographs of such use.
(2) . Numerous photographs of Ihe strip drain lines in Appendix M of the CQA
Report as well as some surveyed strip drain lines in Appendix K
demonstrate .strip drain lines locaiions where Ihe strip slimes drains have
been turned from their original course lo "short-cut intersect" the slimes
drain header perpendicularly. Please demonstrate the method used at
these locations with example photographs of such use as M'ell.
The strip drains were joined using the manufacturer supplied splice fittings (Attachment 2) and
as shown in Photo 3. The curve in some of the strip drain laterals near the tie-in to the header
pipe were made without cutting, kinking, using elbow fittings, or otherwise compromising the
strip composite. Rather, the strip composite was simply bent to form a curve.
c. Specific Strip Drains. As you are aware, there have been several concerns raised
regarding sand bags covering the strip drains. These concerns are mentioned in
the subject DRC letters references at the beginning of this letter. DRC letter dated
December 9, 2010 slates lhat, "each individual line of strip drain and sandbag
cover will be reviewed, corrected as needed, and separately documented by
Geosyntec. Further, lhat an individual record for each strip drain will be made by
Geosyntec in the as-built report fthe CQA Report], or as an addendum thereto.
This element will be critical lo obtain final DRC approval of Ihe strip drain/sand
bag system. "
In the construction inspection chronology, DUSA conveyed the subject CQA
Report to DRC via letter dated November 30, 2010. That date is the same date as
a DRC construction inspection, summarized by our mentioned letter dated
December 9, 2010. That letter stated some general concerns regarding the strip
drain sand bag placement. The subject Geosyntec response letter of December 21,
2010 M'as written to address these DRC concerns. However, Ihe Geosyntec letter,
in general, was not specific to individual strip drains, per the intent of the DRC
letter of December 9, 2010. In our telephone conversation last month, you
mentioned that DUSA has strived to correctly reorient errant sand bag
installation work.
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The CQA Report, Appendix M. provides photographs pertaining lo each strip
drain. After review of such, we request the following:
(1) . Photographs of reworked strip drains 31 and 51 demonstrating no
"piggy-backing " or "fallen dominoes " type stacking of those bags.
Strip drains 31 and 51 were reworked to remove '"piggy-backing" and/or "fallen dominoes" on
16 December 2010. Photographs of the reworked strip drains are included as Photo Nos. 30 and
31 in Attachment 3. Currently, the strip drains are covered with snow and ice and cannot be
entirely exposed without potentially jeopardizing the liner system.
(2) . Photographs of reworked strip drains 15. 16, 17, 18, 19, 20. 21, 22, and
23 demonstrating the following:
(a) . The bags have been reoriented properly.
(b) . That if any parallel bags (per DCN-006) are used, the parallel
bags are not piggy-backed or fallen domino stacked onto the strip
drain sand bags. Our previous comment in paragraph 3a above,
discusses some concerns with respect to DCN-006.
Strip drains 15 through 23were reworked to remove parallel sandbags on 16 December 2010.
Photographs ofthe reworked strip drains are included as Photo Nos. 4 through 27 and 37 through
45 in Attachment 3. Currently, the strip drains are covered with snow and ice and cannot be
entirely exposed without potentially jeopardizing the liner system.
4. We are unaware if a fence has been installed or contemplated lo be installed surround
Ihe Cell 4B site. A fence surrounding waste ponds is a requirement of UAC R317-3-10.8,
M'hich stales, "Fencing. The lagoon area shall be enclosed with nol less than 6 feet high
chain link fence to prevent entering of livestock and to discourage trespassing. Fencing
must not obstruct vehicle traffic on lop of the dikes. A vehicle access gate of sufficient
width to accommodate all maintenance equipment shall be provided. All access gates
shall be provided with locks. " We anticipate that contingent use of Cell 4B may be
authorized, if a fence is installed in a reasonable period of time.
A fence was installed around Cell 4B in December 2010. The fence is shown in Photo Nos. 34
through 36 in Attachment 3.
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If you have any additional questions please feel free to contact me at [phone].
Attachment: 1 - Drawing Sheets No. 1 and 6
2 - MVP Manufacturer's Cut Sheet
3 - Photo Log
Copies to: Harold Roberts, DMC
Irogory T. Corcoran, PE
principal Engineer
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