SECTION CO-952-02224

EXCAVATING, BACKFILLING, AND COMPACTING

[PART 1: GENERAL]{.underline}

1.01 SUMMARY:

A. Section Includes: Excavating, remediating, backfilling, and
compacting for various mill tailing sites.

B. Related Sections:

General Information and Requirements Section 01009

1.02 DEFINITIONS:

A. Unclassified Excavation: Shall consist of the material excavated and
its placement regardless of its nature.

B. Topsoil or Overburden: Surface soil approximately 6 inches in depth
that supports growth of vegetation and contains organic matter. Topsoil
shall be free from subsoil, debris, and stones larger than 1 inch in
diameter.

C. Calcium Carbonate CaCO~3~ Limestone 60 mesh, ground, powder product

D. Calcium Hydroxide Ca(OH)~2~ Lime 10 to 60 mesh, ground, powder
product

E. Compost: A mixture of various decaying organic substances, used for
fertilizing soil.

F. Relocation: Recover existing tailings and relocate to a designated
repository site.

G. In Situ: Situated in the original, natural, or existing place or
position.

H. X-Ray Fluorescence or XRF, is a field test to accurately determine
the composition of soils. The Government will provide the XRF equipment
and operator.

1.03 QUALITY ASSURANCE:

A. Failure Criteria: Not limited to the following:

44436. Settlement of backfill which would allow moisture to pond.

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1.  Improper installation of silt fence which allows tailings excessive
    silt to enter existing live streams.

2.  Failure to apply identified soil amendments/additives at the proper
    application rates and depths.

3.  Excessive disturbance of existing live vegetation.

4.  Working outside defined site boundaries.

1.04 PROJECT/SITE CONDITIONS:

A. Borrow Sources: Borrow on Government land shall be approved in
writing prior to excavation.

B. Removal of Water: The Contractor shall provide and maintain, at all
times during construction, ample means and devices with which to
promptly remove and properly dispose of all water entering the
excavations or other parts of the work without damage to adjacent
property. All excavations shall be kept free from standing water. Any
damage caused by water in the excavations shall be repaired by the
Contractor at the Contractor's expense.

1.05 SUBMITTALS:

A.  General: Submittals shall be in accordance with Section 01009 --
    General Information and Requirements.

[PART 2: PRODUCTS]{.underline}

2.01 MATERIALS:

A.  General: Material excavated shall be unclassified. Backfill material
    shall be approved before use.

B.  Material from excavations shall be used unless it contains ice or
    frozen earth, debris or earth with high moisture content. Materials
    removed in clearing and grubbing shall not be used for backfill.

C.  CaCO~3~ shall have a min. 85% calcium carbonate equivalent.

D. Ca(OH)~2~ shall have a min 85% calcium hydroxide equivalent.

> Calcium Carbonate and Calcium Hydroxide are available from Colorado
> Lime Co., 400 E. Railroad St,
>
> Salida, CO, 719-539-3525. Approved equals shall be considered.

E. Compost shall have a 37% max. moisture content and 40% min. organic
content. Compost is available from Rocky Mountain Soil Inc., 4903 S.
Highway 17, Monte Vista, CO, 719-589-9337. Approved equals shall be
considered.

F. Silt Fence: Propex Geosynthetics, Geotex 2130, or approved equal. A
source of supply is Grand Junction Pipe and Supply, 2868 I-70 Business
Loop, Grand Junction, CO, 81501, 970-243-4604 or 800-748-1564. Silt
fence shall be furnished with steel support posts and wood line posts
and associated fasteners as recommended by the manufacturer.

[PART 3: EXECUTION]{.underline}

3.01 PREPARATION:

A. Dewatering: All work shall be executed under dewatered conditions.
Dispose of excess water by using natural drainage ways near the site to
the extent of their natural capacity when no erosion or other damage is
encountered.

B.  Silt Fence: The Contractor shall measure and determine the amount of
    silt fence required at the time of job commencement. Install
    sediment curtains along live stream banks in accordance with
    manufacturers recommendations and as directed by the Contracting
    Officer.

C.  Topsoil: Topsoil shall be stripped from the repository sites and
    stockpiled for later use.

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3.02 INSTALLATION:

A. Excavation: Perform excavation to the lines, grades, and elevations
indicated to allow for safety, placing of materials and inspection.
Provide proper depth with allowance made for backfill, as shown on the
drawings.

B.  **Work Summary Charts: Refer to the attached maps, tables and
    attachments for the locations and requirements for each site
    designated for remediation.**

  --------------- ---------- ----------- --------- ------------- --------------- ---------------
                                                                                 

  **General Site                                                                  
  Information**                                                                  

  **Site**        **Est.     **Est.      **Area    **Perimeter   **Treatment**   **Repository
                  Tailing    Volume      Acres**   (FT)**                        Dimensions**
                  Depth      (CY)**                                              
                  (IN)**                                                         

  KC01            0-3        242         0.60      1105          Relocation      app. 36\' x
                                                                                 36\' x 5\' deep

  KC05            0-12       693         0.43      990           Relocation      app. 61\' x
                                                                                 61\' x 5\'

  KC06            0-24       4627        1.48      1782          Relocation      app. 158\' x
                                                                                 158\' x 5\'

  KC09            0-30                   1.51      2701          In situ         N/A

  KC09 deep       0-30                   0.30      809           In situ         N/A

  KC09a           0-30                   0.50      1176          In situ         N/A

  KC15            0-3                    0.57      1286          In situ         N/A

  KC16            0-24                   0.44      808           In situ         N/A

  KC16a           0-12                   0.73      1184          In situ         N/A

  KC16b           0-12                   0.26      666           In situ         N/A

  KC16c           0-12       ** **       1.35      1729          In situ         N/A
  --------------- ---------- ----------- --------- ------------- --------------- ---------------

  ---------- ------------------ ------------------ ------------------ ------------------ ----------------- ----------------
             **Required Site                                                                               
             Amendments**                                                                                  

             **CaCO**~3~        **CaCO~3~**        **Ca(OH)~2~**      **Ca(OH)~2~**      **Compost**       

  **Site**   **8\" depth**      **16\" depth**     **8\" depth**      **16\" depth**     **Remediation**   **Repository**

  KC01       **7.0**(*11.7*)                       **3.5**(*5.8*)                        **75.6**          **1.0**

  KC05       **3.7**(*8.5*)                        **3.2**(*7.3*)                        **54.2**          **1.3**

  KC06       **43.2**(*29.2*)                      **46.6**(*31.5*)                      **186.5**         **6.6**

  KC09                          **85.9**(*56.9*)                      **74.3**(*49.2*)   **87.6**           

  KC09 deep                     **2.7**(*8.9*)                        **1.1**(*3.5*)     **37.8**           

  KC09a                         **9.9**(*19.8*)                       **7.7**(*15.4*)    **29.0**           

  KC15       **6.3**(*11.1*)                       **4.2**(*7.4*)                        **71.8**           

  KC16                          **7.5**(*17.0*)                       **5.2**(11.7)      **14.7**           

  KC16a      **10.5**(*14.3*)                      **7.3**(*9.9*)                        **24.9**           

  KC16b      **1.3**(*5.1*)                        **0.9**(*3.4*)                        **8.9**            

  KC16c      **35.6**(*26.4*)                      **24.6**(*18.2*)                      **45.9**           

             NOTE: Values shown                                                                            
             are **Actual                                                                                  
             Tons** to be                                                                                  
             applied per site                                                                              
             and (*Design Tons                                                                             
             per Acre*)                                                                                    
  ---------- ------------------ ------------------ ------------------ ------------------ ----------------- ----------------

C. General Statement of Work:

> **[Tailing Relocation Sites: KC01, KC05, KC06]{.underline}**
>
> 1\. Locate the 3 relocation sites.
>
> 2\. Locate the repository sites for the relocation sites.
>
> 3\. At the existing tailing locations, place silt fencing along the
> stream bank to protect runoff of loose materials prior to removal of
> any materials. Silt fence shall be used to prevent erosion into the
> creek during excavation and until at least the end of the first
> growing season. Every effort should be made to prevent accidental loss
> of tailings into the creek.
>
> 4\. Existing live willows and native vegetation should be preserved
> where possible.
>
> 5\. Remove the top soil at the 3 repository sites and set aside.
> Excavate the repository to the approximate dimensions as stated on the
> Work Summary Chart or as staked. Excavated material shall remain
> separated from the topsoil material.
>
> 6\. Remove tailings to the estimated native soil depths , as shown on
> the Work Summary Chart. The Government XRF operator may decrease
> removal depth if metal concentrations in existing tailings soils are
> suitable (\<4000 ppm) to leave behind. The estimated depths of tailing
> removal range from 3"-24" as identified in the Work Summary Chart.
>
> 7\. Removed tailings will be relocated to the designated repository.
> During the relocation process, the Contractor shall use extreme care
> not to spill or drop tailings along the haul route to the repository.
> Spilled tailings shall be immediately identified and removed to the
> repository. Refer to 3.02E for backfill requirements at the repository
> sites.
>
> 8\. Grade and shape remaining native soils to match and blend into
> surrounding topography.
>
> 9\. After the tailing relocation is complete, the calcium carbonate
> and calcium hydroxide amendments will be added and mixed into the
> remaining native soils to a depth of 8". See the attached table for
> estimated quantities of amendment for each remediation site.
>
> 10\. After the amendments are added, the compost will be added and
> tilled to a depth of 4". See attached table for estimated quantities
> of compost for each remediation site.
>
> 11\. The Contractor shall be prepared to till and mix all amendments
> by making multiple passes with the power equipment. Changes of
> direction and pattern are highly recommended to thoroughly mix all
> materials.
>
> 12\. Haul or access routes and any disturbances outside the defined
> worksites shall be graded and ripped/tilled to match surrounding
> topography.
>
> 13\. Throughout the entire process, the Contractor shall be prepared
> to apply dust control water, if needed. The Contractor and Government
> representative shall closely monitor the work process and determine if
> dust abatement is required. Water will be available on site. The
> Contractor will be required to furnish and operate all equipment.

**[Tailing In-situ Treatment Sites: KC09, KC09deep, KC09a, KC15, KC16,
KC16a, KC16b, KC16c]{.underline}**

> 1\. Locate the 8 in situ sites.
>
> 2\. At the existing tailing locations, place silt fencing along the
> stream bank to protect runoff of loose materials prior to removal of
> any materials. Silt fence shall be used to prevent erosion into the
> creek during in situ remediation process and until at least the end of
> the first growing season. Every effort should be made to prevent
> accidental loss of tailings into the creek.
>
> 3\. Existing live willows and native vegetation should be preserved
> where possible. Existing alluvial gravels and dead vegetation shall be
> crushed and mixed into the tailings during the remediation process.
>
> 4\. The deepest stream side tailings shall be pulled back with an
> excavator or backhoe as far from the stream as possible and
> consolidated into surrounding tailings. Maximum thickness shall be
> 16". Grade and shape tailings to match surrounding topography,
> ensuring that the tailings remain in the designated treatment area.
>
> 5\. Where tailings are less than 12" deep:
>
> \- Place and till calcium carbonate and calcium hydroxide amendments
> to an 8" depth.
>
> \- Place and till compost amendment to a 4"depth.
>
> 6\. Where tailings are greater than 12" deep:
>
> \- Place and till calcium carbonate and calcium hydroxide amendments
> to a 16" depth.
>
> \- Place and till compost amendment to a 4"depth.
>
> 7\. After the amendments are added, compost will be added and tilled
> to a depth of 4". See attached table for estimated quantities of
> compost for each remediation site.
>
> 8\. The Contractor shall be prepared to till and mix all amendments by
> making multiple passes with the power equipment. Changes of direction
> and pattern are highly recommended to thoroughly mix all materials.
>
> 9\. Access routes and any disturbances outside the defined worksites
> shall be graded and ripped/tilled to match surrounding topography.
>
> 10\. Throughout the entire process, the Contractor shall be prepared
> to apply dust control water, if needed. The Contractor and Government
> representative shall closely monitor the work process and determine if
> dust abatement is required. Water will be available on site. The
> Contractor will be required to furnish and operate all equipment.

D.  Equipment Requirements:

> General: The Government cannot dictate the exact power equipment that
> will be used on this job. However, it is recommended that the
> Contractor consider an agricultural field cultivator, 12\" plow,
> spring tooth harrow, commercial rototiller, subsoiler or any
> combination of the above. Also, a crawler tractor with multiple ripper
> teeth capable of penetrating at least 16" may be considered.
>
> The application rate of the calcium carbonate and calcium hydroxide
> amendments is critical. The Contractor shall accurately weigh and
> apply the amendments at the desired rates as shown on the Work Summary
> Chart. The use of a calibrated agricultural fertilizer spreader is
> recommended. The Contractor shall be prepared to accurately
> demonstrate the ability to apply amendments at the desired rates.

The success of the calcium carbonate, calcium hydroxide and compost
amendments is directly related to the depth and even distribution
throughout the incorporation and remediation process. The Government
will be on site to ensure that the amendments are applied correctly.

E. Backfilling:

1.  General: The relocated tailings shall be placed into the designated
    repository site. Even lifts not to exceed 12' shall be placed and
    wheel compacted. Compaction shall be uniform across the full width
    of the repository site.

2.  The excavated materials shall then be placed above the tailings, as
    shown on the drawings to a minimum depth of 2'. Compaction as stated
    above. Grade and shape to blend into adjacent topography.

3.  Evenly spread stockpiled topsoil over the repository site.

4.  Apply compost in accordance with the Work Summary Chart.

> 5\. On the uphill side of the repositories, a diversion ditch will be
> added to redirect runoff from the adjacent hillside so it does not
> flow across the repository.
>
> 6\. On the downhill side of the repositories, a water control ditch
> will be constructed to redirect any excessive runoff from the
> repository

F. Excess Material: Excavated materials which are unsuitable or are in
excess of the requirements for backfill as determined by the Contracting
Officer, shall be deposited as waste at a location in the immediate
vicinity as directed by the Contracting Officer. Grade and shape to
blend into adjacent topography.

G. Testing: The Government will perform any required testing, recording,
and distributing of the results.

[PART 4: MEASUREMENT AND PAYMENT]{.underline}

4.01 METHOD OF MEASUREMENT:

A. Units: The work will be measured and paid for on a lump sum basis,
per Schedule, as shown below.

4.02 BASIS OF PAYMENT

A.  Payment: Payment will be made at the Contract price, as indicated in
    the Bid Schedule, and will include full compensation for the work
    described in the Contract. Payment will be made under:

[Pay Item]{.underline} [Pay Unit]{.underline}

CO-952-02224(1) Schedule A (KC01) . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . Lump Sum

CO-952-02224(2) Schedule B (KC05). . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . Lump Sum

CO-952-02224(3) Schedule C (KC06) . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . Lump Sum

CO-952-02224(4) Schedule D (KC09, KC09deep, KC09a) . . . . . . . . . . .
. . . . . . . . . . . Lump Sum

CO-952-02224(5) Schedule E (KC15). . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . Lump Sum

CO-952-02224(6) Schedule F (KC16, KC16a, KC16b, KC16c). . . . . . . . .
. . . . . . . . . . Lump Sum

END OF SECTION