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Home My WebLink About20101426.tiff Varra Companies, Inc. Office of Special Projects 1431 East 16th Street Greeley,Colorado 80631 Telephone(970)353-8310 Fax/91.0O53-4047 _ J Friday 2 July 201.0 l -2 P 2 LS Weld County Clerk to the Board 915 10`h Street, ri Floor Greeley,Colorado 80632 Subject: Varra Companies, Inc. - Dakolios Pit- Regular Impact (112) Technical Revision Application —Permit M1984-036 Materials submitted to the Colorado Division of Reclamation Mining and Safety (CRMS)—Office of Mined Land Reclamation (OMLR): • Correspondence of 2 July 2010 and attachments. ATTACHEMENTS: • Copy of the 1996 approved Backfill Notice as provided under the 1996 Technical Revision to the permit, M-1984-036. • Correspondence-C.G.R.S. dated 1 July 2010. Your signature below acknowledges receipt of the above referenced material,as attached. The material should be added to the above referenced Application, as originally submitted to the Weld County Clerk to the Board, and made accessible for public review. Received On ,2010 By: Office of the Weld County Clerk to the Board of County Commissioners Y IP �w i 2010-1426 Varra Companies, Inc. DAKOLIos PIT 1 OMLR Techncial Revision—M1984-036 2 July 2010 w c, VarraCompanies, Inc. Office of Special Projects 8120 Gage Street Frederick,Colorado 80516 Telephone(970)353-8310 Fax(970)353-4047 Friday 2 July 2010 To: Jared Ebert, EPS Colorado Office of Mined Land Reclamation 1313 Sherman Street, #215 Denver, Colorado 80203 From: Varra Companies, Inc. Bradford Janes, Professional Forester Subject: M-1984-036 Dakolios Pit— Reply to the Colorado Office of Mined Land Reclamation (Office) Preliminary Adequacy Review correspondence of 27 April 2010. Dear Jared: For greater continuity and ease of reference, we have iterated your comments by item in a graphical box, with our comments in blue following: 1. Updated Post Mine Land Use: As a result of the January 20th, 2010 inspection of the site, the Operator was required to submit a Technical Revision to update the reclamation plan to account for the lining of the two pit excavations with clay. Given the current approved post mine land use is designated as Developed Water Resource, the Division did not require the Operator to submit an amendment to update the current approved land use. However, the Technical Revision indicates the Operator would like to change to post mine land use for a portion of the permit acreage for agricultural use, for farm storage equipment and agricultural material stockpiles. Based off the submitted narrative and the revised map submitted with the Technical Revision, the Division believes about 46.5 acres of land is designated for agricultural use. This acreage is the land not accounted for with the two storage basins and the areas designated for re-soiling and re-vegetation, thus Area 1 and Area 3 (57 acres minus 10.5 acres). The narrative states the current fill area, stockpile yard and recycling area will be used for farm equipment and agricultural material stockpiles. Page 3 of the narrative indicates this farm equipment and agricultural materials stockpile area is designated as Area 2 on the map, however Area 2 on the map is the northwestern reservoir, the Division assumes the applicant meant to state this is Area 3. The reclamation plan map indicates Area 1 and Area 3 will be stabilized with road base instead of being top-soiled and seeded. The current approved reclamation plan calls for top-soiling and re-vegetating the shoreline of the lakes and the periphery areas including the backfilled pit area (Area 3). As stated above, the Operator would like to change the post mine land use for Areas 1 and 3 for agricultural use and not be required to top-soil and re-vegetate these areas. Rule 1.1 (6) requires significant changes Varra Companies, Inc. correspondence of 18 May to the Colorado Office of Mined Land Reclamation(Office) in reply to Office correspondence of 27 April 2010—Dakolios Pit—M-1984-036. Varra Companies, Inc. Office of Special Projects 8120 Gage Street Frederick,Colorado 80516 Telephone(970) 353-8310 Fax(970)353-4047 such as this to be addressed through an amendment to the permit. This request cannot be processed through this Technical Revision. The applicant has two choices: a) Withdraw this Technical Revision and submit an amendment application to change the post mine land use to agricultural for the designated areas. If this option is chosen, the Division will allow the operator to submit an amendment application in 90 days. Or, b) The applicant can modify the submitted technical revision to indicate Areas 1 and 3 will be top-soiled and re-vegetated in accordance with the approved plan. If the applicant chooses to do this, there does not appear to be adequate topsoil stockpiled at the site to reclaim these areas. The operator will need to import adequate growth medium and the Division will need to increase the financial warranty to cover the cost to import this material. The Division is correct in this assumption that the farm equipment and agricultural materials stockpile area is designated as Area 3. Pertaining to the change in use; the 1996 Technical Revision Backfill Notice part (e), specifically calls out for the area of fill to revert to A-Agriculture. The use of farm equipment storage is an allowable use in Weld County for Agricultural lands. We respectfully request that the Division agree, with respect to the approved 1996 Technical Revision, that the aims of reclamation for the area in question were properly clarified at that time and that an amendment to the permit to effect the same is un- necessary in this instance. 2. Hydrologic Balance: Since the Operator installed the clay liners for the two basins prior to the Division's approval, no analysis has been submitted to the Division in regards to the possible impacts the clay liners may have on the surrounding hydrologic balance specifically for mounding and shadowing affects. Given the sites proximity to the Saint Vrain Creek and the likely direction of the ground water flow, shadowing impacts may be negligible. However, the Division has observed clay liners, slurry walls and backfilled pit excavations impede the flow of ground water ad cause mounding impacts to land adjacent to these nearly impervious basins. Was any ground water elevation monitoring conducted at the site for lands adjacent to the clay liners prior to their construction? Please determine what impact the installation of these clay liners and the backfilling activity may have on the surrounding ground water levels. Determine how ground water levels will be monitored to determine if a mounding problem is occurring and how the Operator will mitigate possible mounding problems. Please refer to correspondence of C.G.R.S., dated 1 July 2010, as included with this submittal. Varra Companies, Inc. correspondence of 18 May to the Colorado Office of Mined Land Reclamation(Office) 2 in reply to Office correspondence of 27 April 2010—Dakolios Pit—M-1984-036. Varra Companies, Inc. Office of Special Projects 8120 Gage Street Frederick, Colorado 80516 Telephone(970)353-8310 Fax(970)353-4047 Attachments: 1. Proof of Placement of this material with the Weld County Clerk to the Board. 2. Copy of the 1996 approved Backfill Notice as provided under the 1996 Technical Revision to the permit, M-1984-036. 3. Correspondence - C.G.R.S. dated limy 2010. Varna Companies, Inc. correspondence of 18 May to the Colorado Office of Mined Land Reclamation(Office) 3 in reply to Office correspondence of 27 April 2010—Dakolios Pit—M-1984-036. BA.CKFILL NOTICE- Date: Thursday 1 August 1996 To: Gregg Squire Colorado Division of Minerals & Geology Office of Mined Land Reclamation 1313 Sherman St., # 215 Denver, Colorado 80203 FAX #: (303) 832-8106 From: Bradford Janes Professional Forester P.O. Box 5538 Arvada, Colorado 80006-0538 (303) 427-9419 For: Varra Companies, Inc. 2130 South 96th Street Broomfield, Colorado 80020 FAX # (303) 666-6743 Subject: Dakolios Pit - Permit M-84-036. This submittal is intended to fulfill Rule 3.1.5(9) concerning backfill utilizing inert structural fill generated outside of the approved permit area. (a) The approximate location of the proposed fill is the temporary pond shown on the included aerial photograph. Modification to the permit by technical revision will address under separate cover the intent to backfill this body of water created by past extraction activities, and the utilization of materials generated within the D M G permit area to backfill the same. (b) The approximate volume of the inert material to be backfilled is based upon the following estimate: 29.5 acre pond = 143,005.3 sq. yds. x 3 yds. deep (9 ft.) = 429,015.9 cu. yds. (c) The bottom of part (c) of this correspondence includes the signature as affidavit certifying that the material is clean and inert, as defined in Rule 1.1(20), as follows: Inert Material e means non-water-soluble and non-putrescible solids together with such minor amounts and types of other materials, unless DMG Backfill Notice for Varra Companies, Inc. - Dakolios Pit - Permit M-84-036 1 aNCKVIALNOTICE such materials are acid or toxic producing, as will not significantly affect the inert nature of such solids. The term includes, but is not limited to, earth, sand, grave, rock, concrete which has been in a hardened state for at least sixty days, masonry, asphalt paving fragments, and other inert solids. Christopher L. Varra, President Varra Companies, Inc. (d) The backfilling commenced on an initial level to provide for stockpiling near the point of entry. Active backfilling will not extend beyond this point except to provide for stockpiling at these entry points until this Notice has been approved by DMG. Depending upon the rate at which material is generated on-site or secured from off-site locations, the rate of fill is expected to occur over a period of (10) years, or approximately three (3) surface acres per year. (e) The backfilled lake will create a level surface suitable for agricultural, or if provided for by subsequent permit modification, a wetlands bank. Finished fill will have a cap of overburden (including 6 inches of soil) a minimum of two (2) feet in depth. (f) Voids and settling will be avoided by placement of material into an inundated medium. Fines generated from the wash plant are constantly emptied into the pond at an approximate rate of 30,000 tons per year and will settle into voids displacing the water until the existing basin is filled. Per Part (10) and (11), all mined material to be disposed of within the affected area will be handled in such a manner as to prevent any unauthorized release of pollutants to the surface drainage system; and, no unauthorized release of pollutants to groundwater shall occur from any materials mined, handled or disposed of within the permit area. - end - DMG Backfill Notice for Varra Companies, Inc. - Dakolios Pit - Permit•M-84-036 2 CGENVIRONMENTAL gfIEWO©E July 1, 2010 Mr. Garrett Varra Varra Companies, Inc. 8120 Gage Street Frederick, Colorado 80203 Re: Water Impoundment Hydrology CGRS No. 1-135-10807ab 5-1 0 80 7ab Dear Garrett: This letter and attachments address comments presented by Colorado Division of Reclamation, Mining and Safety regarding mounding and shadowing related to water impoundments. Any impoundment or pond that holds water at an elevation above the surrounding water table will have the potential of increasing the water table elevation (mounding) at some distance from the pond, which is determined by the total groundwater-pond head difference. For ponds that are large in areal extent the distance to no influence on the upstream side is usually less than the downstream side as the head difference will be less based on the water table's hydraulic gradient. The influence imposed by the pond can be estimated by one dimensional unconfined flow solutions presented by McWhorter and Sunada, 1977. Numerical models can be used but we have found model results generally agree well with analytical solutions. An example calculation using a one dimensional unconfined flow equation is presented as Attachment A. In most unconfined flow regimes we consider the distance to no influence (or measurable influence) generally to be on the order of 600 feet. For your operations it appears the pond and groundwater head difference is on the order of five feet. Given this scenario at 100 and 300 feet from the pond the resulting mounding would be four and two feet, respectively. We advise that great care be given when constructing water impoundments (lined or unlined) within 100 feet of any subsurface structures. We have evaluated the affects of impermeable barriers on groundwater hydrology by using the analytical model TWODAN. We simulated a uniform flow field using aquifer properties typically associated with sand and gravel deposits. We then simulated an impermeable barrier within the flow field. The results indicate that the groundwater hydrology is modified but only severely in very close proximity to the barrier. Upstream of the barrier the hydraulic gradient will increase and will decrease downstream of the barrier. Hydraulic gradient changes of between one and two feet are observed within 15 feet of the barrier wall but are negligible at any significant distance from the hydraulic structure. A P.O. Box 1489 Fort Collins, CO 80522 T 800-288-2657 F 970-493-7986 www.cgrs.com Mr.Garrett Varra July 1,2010 Page 2 of 2 graphical output depicting the barrier wall simulation is provided in Attachment B. We also ran simulation in ModFlow, which yielded similar results. If you have any questions regarding this letter, please contact me at 970-493- 7780. Sincerely, CGRS, Inc. y . Adams. P.G. Principal/Hydrogeologist REFERENCES McWhorter, D. and Sunada, D. K., 1977. Groundwater Hydrology and Hydraulics. Water Resource Publications, Littleton, Colorado, pp 146-148. ATTACHMENT A UNCONFINED FLOW ANALYSIS Spreadsheet Calculates One Dimensional Head Distribution (Unconfined) h =Jhi2+X/I,(H2—hie) H Head at no influence(ft) 4808 h Head at point of interest(calculated) � hi Head at retention pond X Distance from pond to point of interest(ft) 300 L Distanct to no influence(ft) "600' ATTACHMENT B BARRIER WALL MODEL RESULTS 86 _ —_ _—_ _—_ _— —_ _ _—-—_ 8 88 - -— —-— —'—_ -— —- - -—- - 90 88 \•.� 8r 92 --- II 94 96 10o 1t —-—-—- Approximate Gradient Line in Uniform Flow X span:0 to 800 Y span:0 to 800 Impermeable Barrier Solution Varra Companies Hello