Division 2 - DEN WQ Improvements IFB.pdf

TECHNICAL SPECIFICATIONS DENVER INTERNATIONAL AIRPORT

DIVISION 02 ANNUAL WATER QUALITY INFRASTRUCTURE IMPROVEMENTS

TABLE OF CONTENTS DESIGN CONTRACT NO. 202265738

CONTRACT NO. XXXXXXXXX

ISSUED FOR Construction: X/X/XXXX Shrewsberry & Associates Revision No. X

DENVER INTERNATIONAL AIRPORT

WATER QUALITY INFRASTRUCTURE IMPROVEMENTS

(SECOND CREEK REGIONAL POND & WORLDPORT POND)

DIVISION 02 – TECHNICAL SPECIFICATIONS

Division 02 – Technical Specifications shall be the Colorado Department of Transportation (CDOT) 2023

Standard Specifications for Road and Bridge Construction. These specifications control construction of this project. The following Project Special Provisions supplement or modify the Standard Specifications and take precedence over the Standard Specifications and plans.

DIVISION 02 – PROJECT SPECIAL PROVISIONS

FOLLOWING SPECIAL PROVISIONS SUPPLEMENT

Revision of Section 202 – Removal of Wall

Revision of Section 202 - Removal of Riprap

Revision of Section 202 – Removal of Structures and Obstructions

Addition of Section 211 – Dewatering and Stream Diversion

Revision of Section 506 – Soil Riprap

Revision of Section 507 – Grouted Boulders and Stacked Grouted Boulders

Revision of Section 507 – Concrete Slope and Ditch Paving (Reinforced)

Revision of Section 601 – Concrete Class D (Wall)

Revision of Section 604 – Outlet Structure

Revision of Section 609 – Curb and Gutter

DIVISION 02 – CDOT STANDARD SPECIAL PROVISIONS

Revision of Section 208 – As-Constructed Survey

Revision of Section 212 – Soil Amendments, Seeding, and Sodding

Revision of Section 601 – Structural Concrete

REVISION SECTION 202 DESIGN CONTRACT NO. 202265738

REVISION OF SECTION 202

REMOVAL OF WALL

Section 202 of the Standard Specifications is hereby revised as follows:

DESCRIPTION

Subsection 202.01 shall include the following:

This work consists of removal of an existing headwall and wingwall structures.

METHOD OF MEASUREMENT

Subsection 202.11 shall include the following:

Removal of Wall will be measured by the number of linear feet as shown in the plans.

BASIS OF PAYMENT

Subsection 202.12 shall include the following:

Payment will be made under:

Pay Item Pay Unit

Removal of Wall Linear Foot

END OF SECTION REVISION

REMOVAL OF RIPRAP

Section 202 of the Standard Specifications is hereby revised as follows:

DESCRIPTION

Subsection 202.01 shall include the following:

This work consists of removal of existing riprap. Riprap removed shall become the property of the contractor and may be reused in the project if materials meet the requirements of Section 506.

METHOD OF MEASUREMENT

Subsection 202.11 shall include the following:

Removal of Riprap will be measured by the square yard of material removed as approved by the engineer.

BASIS OF PAYMENT

Subsection 202.12 shall include the following:

Payment will be made under:

Pay Item Pay Unit

Removal of Riprap Square Yard

REMOVAL OF STRUCTURES AND OBSTRUCTIONS

Section 202 of the Standard Specifications is hereby revised as follows:

DESCRIPTION

BASIS OF PAYMENT

Subsection 202.12 shall include the following:

Payment will be made under:

Pay Item Pay Unit

Removal of Structure Each

Removal of Pipe Linear Foot

Removal of End Section Each

DESIGN CONTRACT NO. 202265738

ADDITION OF SECTION 211

DEWATERING AND STREAM DIVERSION

Section 211 is hereby added to the Standard Specifications for this project as follows:

DESCRIPTION

211.01 Construction dewatering for controlling surface water and groundwater levels in excavations so as to provide stable soil conditions in which to perform the specified construction.

This work includes the proper treatment and disposal of groundwater collected from construction dewatering operations which include, but are not limited to unclassified excavation, muck excavation, structural excavation and shoring.

MATERIALS

211.02 The Contractor shall provide all required materials and equipment to facilitate dewatering and stream diversion activities.

CONSTRUCTION REQUIREMENTS

211.03 The Contractor shall dewater, by pumping or by excavating trenches leading to a positive gravity outlet, to a depth of at least three feet below the underside of any permanent spread footings prior to exposing their proposed bearing surfaces. The dewatering process shall be commenced a sufficient amount of time in advance of placing excavation equipment thereon to prevent undue disturbance of the foundation soil. If in the opinion of the Engineer, equipment is causing undue disturbance, the Engineer may require further drying of the bearing area or place limitations on the type of equipment permitted on the bearing area. The Engineer may require the Contractor to place

(at the Contractor’s expense) additional filter material beyond any limits that may be shown on the plans to compensate for the loss of bearing capacity.

The water level shall be maintained below the level of placed concrete for at least three days before the water level is allowed to rise.

The Contractor’s method of dewatering and water disposal, including pumping and discharge equipment, must be approved by the Engineer prior to implementation. The Contractor shall submit a dewatering plan for review and approval 30 calendar days prior to implementation in accordance with Subsection 105.02. Water Disposal shall be in accordance with Subsection 107.25 – “Water

Quality Control”. Contractor shall obtain all necessary permits and submit copies to the Engineer prior to commencing any dewatering activities.

The Contractor may temporarily divert Second Creek or tributaries during construction. Any related permits are the requirement of the Contractor to obtain. Geotextile membrane shall be placed in the stream to provide a barrier between the stream bed and any material placed in the stream to construct working platforms, diversion berms, etc.

The Contractor’s method of diverting Second Creek or tributaries must be approved by the

Engineer prior to implementation. The Contractor shall submit a diversion plan for review and approval 30 calendar days prior to implementation in accordance with Subsection 105.02. The diversion plan shall include the following:

(a) Method statement addressing all requirements including copies of relevant permits required for stream diversion, and,

(b) Plans and design calculations, sealed and signed by a Professional Engineer registered in the

State of Colorado, supporting the diversion plan including but not limited to:

1. Method for determining design flow,

2. Surface water profiling and conveyance calculations,

3. Phasing plans, and,

4. Site restoration plans showing how to return the stream bed to its original configuration as it was prior to construction.

The Contractor may be legally required to obtain permits associated with dewatering activities within, or off the Right of Way. It is the Contractor’s responsibility to obtain these permits. The

Contractor shall consult with the Engineer, and contact the Colorado Department of Public Health and Environment (CDPHE) or other appropriate federal, state, or local agency to determine the need for any permit. The Contractor shall obtain all appropriate permits, equipment and labor necessary to dewater the location.

Discharge of water from dewatering operations shall be in accordance with Section 107.25 Water

Quality Control. Required dewatering of excavations shall be conducted in a manner that avoids pollution and erosion. Any contaminated water from dewatering operations shall not be directly discharged into any state waters including wetlands irrigation ditches, canals, or storm sewers.

Discharge into sanitary sewers will not be allowed unless written permission is obtained from the owner or controlling authority and a copy of this approval submitted to the engineer. A complete application must be submitted to CDPHE at least 30 days prior to dewatering operations. The contaminated water will be containerized, transported and disposed of in accordance with all local, state and federal regulations. Uncontaminated water from dewatering operations shall be contained in basins for dissipation by infiltration or evaporation, shall be hauled away from the project for disposal in accordance with applicable laws and regulations, otherwise a dewatering permit will be required for any other application including discharge to land or surface waters. The

Contractor shall apply for and obtain the Construction Dewatering Permit with the Colorado

Department of Health and Environment (CDPHE). A complete application must be submitted to

CDPHE at least 30 days prior to dewatering operations.

The Contractor shall submit a Dewatering Plan to the Engineer at least 4 weeks prior to the proposed start of dewatering operations. The Dewatering Plan shall provide complete details of the Contractor’s method for construction dewatering including

1) Copies of all permits required for dewatering treatment of and/or disposing of water.

2) If applicable, copies of agreements for disposing of water in storm sewers, sanitary sewers, etc.

3) Equipment description including size, number, type, capacity and location of equipment during dewatering operations.

4) Methods of testing groundwater to determine appropriate disposal

5) Detailed methods of disposal of water

6) If applicable name of facility where contaminated water is to be delivered.

If a construction dewatering permit is needed, in accordance with permit procedures, contractor shall fill out and submit a monthly discharged monitoring report (DMR) to CDPHE for the life of the permit. Copies of monthly submittals shall be provided to Region 4 CDOT Environmental

Project Manager.

Discharge of water obtained from dewatering into ground water or surface water locations without a CDPS Groundwater Infiltration Permit will be considered to be in violation of the Federal Clean

Water Act. All penalties associated with this violation shall be at the Contractor's expense. The permit shall be obtained before start of dewatering.

The Contractor shall furnish all design, materials, tools, equipment, facilities, and services as required for providing the necessary dewatering work and facilities. Provide back-up equipment as necessary for replacement and for unanticipated emergencies. Remove dewatering system from

Project site on completion of dewatering.

METHOD OF MEASUREMENT

211.03 Dewatering will not be measured but will be the amount required to complete the work as shown in the plans.

BASIS OF PAYMENT

211.04 Payment will be made under:

Pay Item Pay Unit

Dewatering and Stream Diversion Lump Sum

All the work listed above, including but not limited to design and preparation of the Dewatering

Plan, DMR reports, labor, materials, requirements of permits obtained, required equipment and removal of equipment, will not be measured and paid for separately, but shall be included in the work. The Contractor shall be liable for any penalty (including monetary fines) applied to the

Department caused by the Contractor’s noncompliance with any dewatering permit or certification.

Monetary fines shall be deducted from any money due to the Contractor. If the monetary fine is in excess of all the money due to the Contractor, then the Contractor shall pay to the Department the amount of such excess. The Contractor will not receive additional compensation, or time extensions, for any disruption of work or loss of time caused by any actions brought against the

Contractor for failure to comply with dewatering controls.

If contaminated groundwater is encountered, additional costs related to removal, sample collection, analytical testing, containerization, transportation and disposal or treatment of the contaminated groundwater will be paid under Section 250 Hazardous Waste Disposal.

REVISION OF SECTION 506

SOIL RIPRAP

Section 506 of the Standard Specifications is hereby revised for this project as follows:

Subsection 506.01 shall include the following:

The work includes excavation, grading, and installation of riprap, boulders, soil riprap, void-filled riprap, and bedding placed at the locations shown on the drawings. The materials to be used and the construction of such structures shall be as specified herein.

Subsection 506.02 shall include the following:

The Contractor shall cooperate with the Engineer in obtaining and providing samples of all specified materials. The Contractor shall submit certified laboratory test certificates for all items required in this section.

Materials shall conform to the following requirements specified and all referenced sections.

A. Riprap

1. Riprap used shall be the type designated on the drawings and shall conform to Table 1.

2. The riprap designation and total thickness of riprap shall be as shown on the drawings. The maximum stone size shall not be larger than the thickness of the riprap.

3. Neither width nor thickness of a single stone of riprap shall be less than one-third (1/3) of its length.

4. The specific gravity of the riprap shall be two and one-half (2.5) or greater.

5. Riprap specific gravity shall be according to the bulk-saturated, surface-dry basis, in accordance with AASHTO T85.

6. The bulk density for the riprap shall be 1.3 ton/cy or greater.

7. The riprap shall have a percentage loss of not more than forty percent (40%) after five hundred

(500) revolutions when tested in accordance with

AASHTO T96.

8. The riprap shall have a percentage loss of not more than ten percent (10%) after five (5) cycles when tested in accordance with AASHTO T104 for ledge rock using sodium sulfate.

9. The riprap shall have a percentage loss of not more than ten percent (10%) after twelve (12) cycles of freezing and thawing when tested in accordance with AASHTO T103 for ledge rock, procedure A.

10. Rock shall be free of calcite intrusions.

11. Gradation:

a. Each load of riprap shall be reasonably well graded from the smallest to the largest size specified.

b. Stones smaller than the two to ten percent (2 to 10%) size will not be permitted in an amount exceeding ten percent (10%) by weight of each load.

c. Control of gradation shall be by visual inspection. However in the event the Engineer determines the riprap to be unacceptable, the Engineer shall pick two (2) random truckloads to be dumped and checked for gradation.

1) Mechanical equipment and labor needed to assist in checking gradation shall be provided by the Contractor at no additional cost.

12. Color:

a. The color of the riprap shall approved by the Engineer prior to delivery to the project site.

b. Color shall be consistent on the entire project and shall match the color of rock to be used for all other portions of the work.

13. Broken concrete or asphalt pavement shall not be acceptable for use in the work.

14. Rounded riprap (river rock) is not acceptable, unless specifically designated on the drawings.

B. BOULDERS

1. Boulders used shall be the type designated on the drawings and shall conform to Table 2.

2. The specific gravity of the boulders shall be two and one-half (2.5) or greater.

3. Boulder specific gravity shall be according to the bulk-saturated, surface-dry basis, in accordance with AASHTO T85.

4. The bulk density for the boulder shall be 1.3 ton/cy or greater.

5. The boulders shall have a percentage loss of not more than forty percent (40%) after five hundred

(500) revolutions when tested in accordance with AASHTO T96.

6. The boulders shall have a percentage loss of not more than ten percent (10%) after five (5) cycles when tested in accordance with AASHTO T104 for ledge rock using sodium sulfate.

7. The boulders shall have a percentage loss of not more than ten percent (10%) after twelve (12) cycles of freezing and thawing when tested in accordance with AASHTO T103 for ledge rock, procedure

A.

8. Rock shall be free of calcite intrusions.

9. Color:

a. The color of the boulders shall approved by Engineer prior to delivery to the project site.

b. Color shall be consistent on the entire project and shall match the color of rock to be used for all other portions of the work.

C. SOIL RIPRAP

1. Rock requirements are to comply with riprap as specified in Article Materials.

2. The soil material shall be native or topsoil and mixed with sixty-five percent (65%) riprap and thirty five percent (35%) soil by volume.

3. Soil riprap shall consist of a uniform mixture of soil and riprap without voids.

D. VOID-FILLED RIPRAP

1. Rock requirements are to comply with riprap material specifications in Paragraph A.

2. Samples of riprap and void-fill materials shall be submitted for the review and approval of the

Engineer prior to construction.

3. Where “Void-Filled Riprap” is designated on the drawings, riprap shall be mixed with the materials and associated proportions listed in Table 3 and Table 4 to fill the voids of the riprap.

4. If specified, an alternate void-filled riprap mix that includes river cobble shall be used; this mix appears in Table 5 and Table 6.

5. Mix proportions and material gradations in Tables 3 through 6 are approximate and are subject to adjustment by the Engineer. No adjustment in unit price for void-filled riprap will be allowed based on modifications to the mix proportions.

E. BEDDING:

1. Gradation for granular bedding shall conform to Table 7.

2. Granular bedding designation and total thickness of bedding shall be as shown on the drawings.

3. Granular bedding shall meet the same requirements for specific gravity, absorption, abrasion, sodium sulfate soundness, calcite intrusion, and freeze-thaw durability as required for riprap.

a. Broken concrete asphalt pavement or sledge, shall not be acceptable for use in the work.

Rounded river rock is not acceptable unless specifically designated on the drawings.

b. The requirements for the wear test in AASHTO T96 shall not apply.

F. FEATURE BOULDERS:

1. Feature Boulders shall consist of the same material as boulders, differing only by size.

2. Feature Boulders shall meet the same requirements for specific gravity, absorption, abrasion, sodium sulfate soundness, calcite intrusion, and freeze-thaw durability as required for boulders

3. Feature Boulders shall have a minimum dimension of four (4) feet, or as shown on the drawings.

Subsection 506.03 shall include the following:

A. Channel slope, bottom, or other areas that are to be protected with riprap, boulders, soil riprap, or void-filled riprap shall be free of brush, trees, stumps, and other objectionable material and be graded to a smooth compacted surface as shown on the drawings.

B. the Contractor shall excavate areas to receive riprap to the subgrade as shown on the drawings accounting for granular bedding.

C. the Contractor shall excavate areas to receive boulders, soil riprap, or void-filled riprap to the specified depth (bedding material is not required for boulders, soil riprap, or void-filled riprap).

D. Subgrade Materials:

1. The subgrade materials shall be stable.

2. If unsuitable materials are encountered, they shall be removed and replaced as Muck Excavation, for subgrade that has been excavated in undisturbed soil.

E. Additional Compaction:

1. Additional compaction shall not be required unless specified by the Engineer.

2. When subgrade is built up with embankment material it shall be compacted to ninety five percent

(95%) maximum density (ASTM D698).

F. Bedding:

1. After an acceptable subgrade is established, bedding shall be immediately placed and leveled to the specified elevation on the drawings.

2. Immediately following the placement of the bedding material, the riprap shall be placed.

3. If bedding material is disturbed for any reason, it shall be replaced and graded at the Contractor’s expense.

4. Contamination:

a. In-place bedding materials shall not be contaminated with soils, debris or vegetation before the riprap is placed.

b. If contaminated, the bedding material shall be removed and replaced at the Contractor’s expense.

506.03.01 PLACEMENT

A. RIPRAP

1. Following acceptable placement of granular bedding, riprap placement shall commence as follows:

a. Machine Placed Riprap:

1) Riprap shall be placed on the prepared slope or channel bottom areas in a manner which will produce a reasonably well graded mass of stone with the minimum practicable percentage of voids.

2) Riprap shall be machine placed, unless otherwise stipulated in the drawings or specifications.

3) It is the intent of these specifications to produce a fairly compact riprap protection in which all sizes of material are placed in their proper proportions. Unless otherwise authorized by the Engineer, the riprap protection shall be placed in conjunction with the construction of embankment or channel bottom with only sufficient delay in construction of the riprap protection, as may be necessary, to allow for proper construction of the portion of the embankment and channel bottom which is to be protected.

b. Slope Placement:

1) When riprap is placed on slope, placement shall commence at the bottom of the slope working up the slope.

c. The entire mass of riprap shall be placed on either channel slope or bottom so as to be in conformance with the required gradation mixture and to line, grade, and thickness shown on the drawings.

d. Riprap shall be placed to full course thickness at one operation and in such a manner as to avoid displacing the underlying bedding material. Placing of riprap in layers, or by dumping into chutes, or by similar methods shall not be permitted.

e. All material used for riprap protection for channel slope or bottom shall be placed and distributed such that there shall be no large accumulations of either the larger or smaller sizes of stone. Some hand placement may be required to achieve this distribution.

f. The basic procedure shall result in larger materials flush to the top surface with faces and shapes arranged to minimize voids, and smaller material below and between larger materials.

g. Surface grade shall be a plane or as indicated, but projections above or depressions under the finished design grade by more than ten percent (10%) of the rock layer thickness shall not be allowed.

h. Smaller rock shall be securely locked between the larger stone. It is essential that the material between the larger stones not be loose or easily displaced by flow or by vandalism.

i. The stone shall be consolidated by the bucket of the backhoe or other means that will cause interlocking of the material.

j. All rock is to be placed in a dewatered condition beginning at the toe of the slope or other lowest point.

k. the Contractor shall maintain the riprap protection until accepted. Any material displaced for any reason shall be replaced to the lines and grades shown on the drawings at no additional cost to the owner. If the bedding materials are removed or disturbed, such material shall be replaced prior to replacing the displaced riprap.

2. Hand Placed Riprap:

a. Hand placed riprap shall be performed during machine placement of riprap and shall conform to all the requirements of this specification.

b. Hand placed riprap shall also be required when the depth of riprap is less than two (2) times the nominal stone size, or when required by the drawings or specifications.

c. After the riprap has been placed, hand placing or rearranging of individual stones by mechanical equipment shall be required to the extent necessary to secure a flat uniform surface and the specified depth of riprap, to the lines and grades as shown on the drawings.

3. Soil Replacement Over Riprap:

a. Where riprap is designated to be buried, place onsite excavated material that is free from trash and organic matter in riprap voids by washing and rodding.

b. Prevent excessive washing of material into stream.

c. When voids are filled and the surface accepted by the Engineer, place a nominal six (6) inches of topsoil over the area, or as designated on the drawings.

d. Fine grade, seed, and mulch per the specifications.

B. BOULDERS

1. Following excavation and acceptance of subgrade by the Engineer Boulder placement shall commence as follows:

a. Boulders shall be placed on the prepared subgrade in a manner which will minimize voids.

b. Voids between boulders exceeding 4" shall be chinked.

2. If Boulders are to be grouted, boulders shall be installed according to Section 507 Grouted

Boulders and Stacked Grouted Boulders.

C. SOIL RIPRAP

1. Adjacent stockpiles of riprap and soil shall be created and mixing done at the stockpile location, not at the location where soil riprap is to be placed.

2. Mix thirty-five percent (35%) soil by volume with stockpiled riprap, using additional moisture and control procedures that ensure a homogenous mixture; where the soil fills the inherent voids in the riprap without displacing riprap.

3. With prior approval of the Engineer, layering the riprap and soil instead of premixing may be allowed if the native soil is granular.

4. Place a first layer of smaller soil riprap of approximate d50 thickness. Then place the top layer with surface rocks that are largely d50 or greater, filling voids as necessary with smaller planted riprap.

Create a smooth plane as described in Paragraph A.

5. The mixture shall be consolidated by large vibratory equipment or backhoe bucket to create a tight, dense interlocking mass.

6. The soil shall be further wetted to encourage void filling with soil.

7. Any large voids shall be filled with rock and small voids filled with soil.

8. Excessively thick zones of soil prone to washing away shall not be created (for example, no thicknesses greater than six (6) inches).

9. For buried soil riprap, the top surface shall be covered with four (4) inches of topsoil such that no rock points are protruding.

10. The final surface shall be thoroughly wetted for good compaction, smoothed and compacted by vibrating equipment; the surface shall then be hand raked to receive planting or seeding.

D. VOID-FILLED RIPRAP

1. The Engineer and/or the Construction Inspector shall observe mixing and placing of the material.

2. Approved individual component materials of void-filled riprap mix shall be delivered to site in separate marked stockpiles. Mixing shall be accomplished using a front end loader or other approved means to add the specified number of “loader buckets” of each material to a mixing stockpile. Ensure that each loader bucket comprises an approximately equal volume. If the loader operator is only able to fill the bucket partially full with large riprap (due to the force required to push the bucket into the pile), but uses full buckets of finer material, the mix proportions will not be correct. Avoid picking up excessive amounts of native soil from the subgrade under the stockpiled materials during the loader bucket mixing operations. The Engineer may reduce or eliminate the volume of topsoil added to the mixture based on the amount of native soil was incorporated during the bucket mixing operation.

3. Once all the materials have been added to the mixing stockpile in the specified proportions, thoroughly mix the pile using a loader, large track-hoe excavator, or other approved means to fill the voids of the riprap without displacing the riprap or creating pockets of finer material absent of riprap.

4. Segregation of materials shall be minimized when hauling from the stockpile to the installation location. Remixing shall occur as necessary to correct for any segregation as the material is placed.

5. The loose material shall be placed in a single lift of sufficient height such that final grade will be achieved upon compaction. Additional mixing with a track excavator shall be required after initial placement to ensure that the void-filled riprap is thoroughly mixed and no segregation or excessive amount of smaller void-fill material is present on the surface. The mixing and placement process shall result in larger riprap (D50 size or larger) flush to the top surface with faces and shapes arranged to minimize voids, and smaller material between and below larger materials.

6. If the top of the compacted material is below final grade, placement of only the smaller void-fill materials to achieve final grade will not be permitted. Additional void-filled riprap shall be added and the entire section mixed with a track excavator to eliminate the presence of smaller void-fill material on the surface.

7. Avoid segregation of materials and remix any section where the combined material consists primarily of the void-fill materials. The density and interlocking nature of riprap in the mixed material shall essentially be the same as if the riprap was placed without filling the voids. This requires care and persistence on the part of the Contractor to install the work and on the part of the Engineer to assure that the work is installed correctly.

8. At the direction of the Engineer, a 50:50 mixture of pit run and Type II bedding shall be sprinkled on the surface of the void-filled riprap and washed-in with water using a high pressure hose to fill-in small voids. This shall be done just prior to compaction of the void-filled riprap.

9. If specified as part of the cobble mix, the top dressing of cobbles shall also be mixed in on the surface of exposed sections of void-filled riprap material prior to compaction of the riprap material.

10. Compaction of the void-filled riprap shall be performed by running over the void-filled riprap with a large, heavy duty track excavator or dozer. The moisture content of the mixture shall be at optimum conditions prior to compaction and water shall be added, as necessary, at the direction of the

Engineer. Compaction of void-filled riprap shall be reviewed and approved by the Engineer.

11. Where indicated on the drawings, a surface layer of 4 to 6 inches moist topsoil shall be placed over the void-filled riprap. The topsoil surface layer shall be compacted to approximately 85% of maximum density and within two percentage points of optimum moisture in accordance with ASTM

D698. Topsoil shall be added to any areas that settle.

12. the Contractor shall install a test section of at least 100 square feet of void-filled riprap for the review and approval of the Engineer prior to installation of the remaining void filled-riprap.

13. Elevation tolerance for the void-filled riprap shall be 0.10 feet. Thickness of void-filled riprap shall be no less than thickness shown and no more than 2-inches greater than the thickness shown.

E. FEATURE BOULDERS

1. Feature Boulders serve an aesthetic function and as such shall be placed and rotated into final position as directed by the Engineer in order to achieve the desired result.

5.06.03.02 REJECTION OF WORK AND MATERIALS:

A. Engineer will reject placed riprap, boulders, soil riprap and bedding that do not conform to this section.

the Contractor shall immediately remove and re-lay the riprap, boulders, soil riprap, void-filled riprap, and bedding to conform to the specifications.

B. Riprap, boulders, soil riprap, void-filled riprap and bedding that do not conform to this section shall be rejected, whether delivered to the job site or placed.

C. Rejected riprap, boulders, soil riprap and bedding shall be removed from the project site by the

Contractor at the Contractor’s expense.

Subsection 506.04 shall include the following:

Payment for boulders, riprap, soil riprap, void-filled riprap, and bedding shall include but is not limited to excavation for boulder, riprap, soil riprap, void-filled riprap, bedding and embankment material for filling existing voids; subgrade preparation, furnishing and placing boulders, riprap, soil riprap, void-filled riprap, and bedding; and disposal of excess excavated material. Payment shall be made at the contract unit price and shall include full compensation for all labor, equipment, materials, transportation, and all other appurtenant items to complete the work.

Subsection 506.05 shall include the following:

Payment shall be made at the contract unit price for boulders, riprap, soil riprap, void-filled riprap, and bedding and shall include full compensation for all labor, equipment, materials, transportation, and all other appurtenant items to complete the work.

Soil Riprap (9”) Cubic Yards

Soil Riprap (12”) Cubic Yards

Type I (CDOT CL A) Cubic Yards

Type II (CDOT CL B) Cubic Yards

REVISION OF SECTION 507

GROUTED BOULDERS AND STACKED GROUTED BOULDERS

Section 507 of the Standard Specifications is hereby revised for this project as follows:

Subsection 507.01 shall include the following:

This work consists of installing grouted boulders, stacked grouted boulders, and grouted rock retaining walls constructed at the location (s) shown on the drawings.

Subsection 507.02 shall include the following:

The Contractors shall provide all materials and incidentals necessary to install the grouted boulders and stacked grouted boulders. The Contractor shall submit a mix design in writing to the Engineer for approval prior to placement of any grout. The Contractor shall cooperate with the Engineer in obtaining and providing samples of all specified materials. The Contractor shall submit certified laboratory test certificates for all items required in this section.

Materials shall conform to the following requirements specified and all referenced sections.

Boulders shall meet the requirements of Section 506 Riprap (Special). Rhyolite rock shall not be used for any grouted boulders.

Gradation:

a. Each load of boulders shall conform to the dimensions specified on the drawings and in Section 506 Riprap (Special)

b. Boulders for a boulder edge shall have a maximum ratio of largest to smallest rock dimension shall be 1.5 or as shown on the drawings.

c. Control of gradation will be by visual inspection.

1) In the event the Engineer determines the boulders to be unacceptable, the

Engineer will pick two random truckloads to be dumped and checked for gradation.

2) Mechanical equipment and labor needed to assist in checking gradation shall be provided by the Contractor at no additional cost to the Owner if the boulders do not meet the specified gradation.

3) If the boulders do meet the gradation specified, the Owner will pay for the equipment and labor required for checking.

Color:

a. The color of boulders shall meet the requirements of Section 506 Riprap (Special).

Grout:

1. Concrete for the grout shall be an approved batch meeting the following requirements:

a. All grout shall have a minimum 28-day compressive strength equal to 3,200 psi.

b. One cubic yard of grout shall contain a minimum of six (6) sacks of Type II

Portland cement.

c. A maximum of 25% Type F Fly Ash may be substituted for the Portland cement.

d. Aggregate for the grout shall consist of 70% natural sand (fines) and 30% 3/8-inch rock (coarse).

e. Slump shall be four (4) inches to six (6) inches.

f. Air entrainment shall be 5.5% - 7.5%.

g. Grout shall contain one and one-half (1-1/2) pounds of Fibermesh, or approved equivalent, per cubic yard of grout.

h. Grout shall contain one and one-half (1-1/2) pounds of Fibermesh, or approved equivalent, per cubic yard of grout.

i. Color Additive in required amounts shall be used when so specified by contract.

Subsection 507.07 shall include the following:

Grouted boulders shall be placed at the locations as shown on the drawings and installed with the following requirements:

1. Subgrade:

a. The subgrade to receive each boulder shall be excavated and any unstable material shall be removed.

b. Grouted Boulders shall be placed on subgrade without granular bedding unless approved by the Engineer.

c. Material approved by the Engineer shall be placed and compacted in a maximum of four-inch (4") lifts to ninety five percent (95%) of Maximum Standard Proctor Density

(ASTM D698) to re-establish the subgrade of each boulder.

d. Unstable material shall be removed from the project site and disposed of by the

Contractor. Removal and replacement of unstable material shall only be completed at the direction of the Engineer and shall be paid for under Muck Excavation.

e. Subgrade shall be excavated a minimum of 6" to a maximum of 12" behind boulders.

f. Backfill behind boulders shall be compacted to ninety five percent (95%) Maximum

Standard Proctor Density (ASTM D698). Care shall be taken during compaction to avoid disturbing and/or damaging the integrity of the boulder channel edge.

g. Finished grades and subgrade for boulders shall be determined from the height of each boulder used.

2. Boulders

a. The top of all boulders shall be as indicated on the drawings.

b. The boulders shall be carefully picked and arranged so that adjacent rock surfaces match within two (2) inches in top elevation and two (2) inches along the vertical exposed face or channel side of rock.

c. Boulders shall be placed such that adjacent boulders “touch” each other and voids do not exceed four (4) inches. It is the intent of construction to minimize voids and grout placed between boulders.

d. The Contractor shall, if deemed necessary, support the boulders from falling over before and during the placement of grout, backfill, and completing compaction work on either side of the boulder.

e. Smaller rocks shall be “chinked in” to fill all voids behind the boulders. Smaller rocks shall also be used to "chink in gaps larger than four (4) inches. Placement shall be approved by the Engineer prior to grouting.

3. Grouting:

a. Prior to placing the grout, any type of debris, fines, smaller rock, or silt shall be removed from around or under and on the boulders.

b. Dewatering shall be implemented to guarantee that the grout will not be placed in water and for a period of twenty-four (24) hours after the grout has been placed.

c. Keep boulders receiving grout wet at all times prior to receiving grout.

d. The concrete grout shall be placed by injection methods by pumping under low pressure, through a two- (2") inch maximum diameter hose to ensure complete penetration of the grout into the void area as detailed on the drawings. The grout mix shall be stiffened and other measures taken to retain the grout between the boulders.

e. Grout placement shall begin at the bottom of the lowest boulder and proceed upward to ensure no air voids exist between the grout, subbase, and boulders.

f. Grout shall be placed up to a height of one-half (1/2) of the diameter of the top row of boulders or as directed by the Engineer and shall be placed in the voids and behind the boulders and not on the surface of the rocks.

g. A “pencil” vibrator shall be used to make sure all voids are filled between the boulders from the subgrade and around the boulders to a depth as shown on the drawings.

The “pencil” vibrator may be used to smooth the appearance of the surface, but the

Contractor shall use a wood float to smooth and grade the grout around the boulders.

h. Grout between boulders shall be recessed one third (1/3) the diameter of the boulders on the side facing the channel.

i. Grout should be troweled out and finished to minimize visibility.

j. Clean and wash any spillage before the grout sets so the visual surfaces of boulders will be free of grout to provide a clean, natural appearance, or if washing does not clean off grout residue, the Contractor shall wash off any grout residue with muriatic acid and water, using a brush to scrub off the residue.

k. Grout shall receive cold or hot weather protection. In hot, windy, or dry conditions where rapid surface evaporation may occur, apply evaporation reducer.

Subsection 507.14 shall include the following:

Payment for boulders, shall include but is not limited to excavation for boulder and embankment material for filling existing voids; subgrade preparation, furnishing and placing boulders; and disposal of excess excavated material. Payment shall be made at the contract unit price and shall include full compensation for all labor, equipment, materials, transportation, and all other appurtenant items to complete the work.

B24 24” Grouted Boulders Each

Mortar or concrerte used for gout in grouted boulders shall not be measured and paid for separately but shall be included in the work. Payment for Grouted Boulders and Stacked Grouted Boulders will be full compensation for all work and materials required to complete the item.

Revision of Section 507

Concrete Slope and Ditch Paving (Reinforced)

Revise Section 507 of the Standard Specifications for this project as follows:

Subsection 507.01 shall include the following:

This work shall include reinforced concrete paving for the forebays, thrust blocks, and trickle channels.

MATERIALS

Subsection 507.02 shall include the following:

Reinforcement for the forebays, thrust blocks, and trickle channels shall include welded wire fabric and #4 rebar as specified on the plans.

CONSTRUCTION REQUIREMENTS

Subsection 507.08 shall include the following:

Contractor to sawcut ¼” x 1” deep joints in the forebay bottom slab at 10’-0” maximum spacing. Contractor shall place a sawcut joint at each forebay vertex. Contractor shall provide joint plan for approval prior to construction.

Subsection 507.14 shall include the following:

Payment will be made under:

Pay Item Pay Unit

Concrete Slope and Ditch Paving (Reinforced) Cubic Yard

All materials and labor associated with the forebays, thrust blocks and trickle channels will not be paid for separately but shall be included in the work.

Revision of Section 601 Concrete Class D (Wall)

Revise Section 601 of the Standard Specifications for this project as follows:

Subsection 601.20 shall include the following:

All reinforcing steel necessary to construct the retaining walls as shown on the plans shall be included in the cost of Concrete Class D (Wall).

Revision of Section 604

Outlet Structure

Revise Section 604 of the Standard Specifications for this project as follows:

Subsection 604.01 shall include the following:

This work consists of the construction of the Outlet Structures, including the micropools, at the Second Creek Regional Water Quality Pond and the Worldport Water Quality Pond.

METHOD OF MEASUREMENT

Subsection 604.06 shall include the following:

Outlet Structure will be measured by the actual number of units manufactured or constructed and installed. The pay item shall include all work, materials, and labor required to manufacture or construct and install the Outlet Structure as shown on the design plans and details.

Subsection 604.07 shall include the following:

The accepted quantities, measured as provided above, will be paid for at the contract price for each of the pay items listed below that appear in the bid schedule.

Payment will be made under:

Pay Item Pay Unit

Outlet Structure Each

All materials and labor associated with the Outlet Structure will not be measured and paid for separately but included in the work. Reinforcing steel, structural concrete, bedding material, trash racks, steel plates, anchors, as well as all other materials required to complete the item shall be included in the work.

Revision of Section 609

Curb and Gutter

Revise Section 609 of the Standard Specifications for this project as follows:

Subsection 609.01 shall include the following:

This work consists of the construction of the curb head along the trickle channel for the

Second Creek Regional Water Quality Pond and the Worldport Water Quality Pond. The curb and gutter dimensions shall be as shown on the plans.

Subsection 609.07 shall include the following:

Payment will be made under:

Curb and Gutter Type 2 (Section IM)(Special) Linear Foot

October 1, 2023

Revision of Section 208 As-Constructed Survey

Revise Sections 208 of the Standard Specifications as follows:

Add the following to Subsection 208.10(b):

(b) As-Constructed Survey. The Contractor shall complete an as-constructed survey of each Permanent Water Quality (PWQ) control measure (CM). Surveys are conducted on all PWQ CM for two reasons:

1. To provide initial location information for CDOT PWQ CM inventory, and

2. To provide necessary data for completion of the Pond Information Certification

(PIC) for PWQ CM designed using the Water Quality Capture Volume

(WQCV)

Standard (Extended Detention Basin (EDB), Retention Pond, etc.).

The Contractor shall submit the as-constructed survey to the Project

Engineer before payment for and final acceptance of any items required to construct the PWQ features. The electronic as-constructed survey shall conform to the requirements of Section 625, use Terrain Modeling Survey

System (TMOSS) codes, and shall include the following information:

1. The Contractor's Professional Land Surveyor’s (PLS) digital terrain model with the electronically sealed field-collected information report.

2. The PWQ survey shall include all horizontal and vertical reference points for all PWQ features as determined by the Contractor’s surveyor.

3. The contours shall be shown at 1-foot intervals with major contours labeled at 5-foot increments.

4. The bottom of the EDB elevations along the toe of embankment slope and top and bottom of trickle channel elevations, to verify positive drainage throughout the basin with labels of features, elevation, and the WQCV elevation as shown on the plans.

5. The top of wall or dam elevation on the survey to verify freeboard (distance between high- water mark and top of wall or dam elevation) along the EDB, and the top width of the embankment along the perimeter of the EDB.

6. A detail of each forebay located at the outfall of each incoming storm drain into the EDB, including plan dimensions with tops of walls, tops of slabs, pipe invert elevations, and pipe diameters.

7. The basin location related to property lines (measured distances), right-of-way lines, buildings, roads, access paths, and other easements.

8. The details of the outlet control structure, including labels of features and elevations, and notes indicating if the features are the same as the design plan, or the reason they are different in the as-constructed survey.

9. The details, including labels and elevations of all grates, racks, screens, and any other materials intended to prevent clogging of the outlet structure orifices by debris of any kind. Label all features and elevations on the as-constructed deliverable CADD 3D model and Survey report.

10. The access and maintenance easements per the ROW plans around the EDB, including the maximum slope of the access easement.

11. The submitted CADD 3D model shall include the following:

a. All control marks set per item 2, and other Project Controls as shown on the sealed Project Control diagram; ensure that contour lines are continuous, closed, unbroken polylines.

b. Grade spot elevations and breaklines used to create the contours.

c. Elevations for all applicable items listed in 2-10 above.

d. Correct contours.

e. Initial /EDB volume calculation report sealed by the

PLS of the data collection.

f. Geocoordinate system that conforms to project datum.

g. Survey information shall be compatible with the latest 3D digital modeling software.

Submit the as-constructed survey, including field survey data, survey report, and electronic model files as a complete package to the Engineer. Allow 10 days for CDOT review of the field survey data.

If the field survey data, survey report or electronic model files indicate the control measure was incorrectly constructed, the

Contractor shall perform necessary corrective work to the PWQ

CM to ensure compliance with design, at no cost to the project, as directed by the Engineer. Payment will not be made for any

PWQ items until corrections have been made and another survey has been completed, compared, and accepted.

The Contractor shall clean all Permanent Water Quality Control Measures before the PWQ Survey, final walkthrough and final acceptance.

Subsection 208.12 shall include the following:

Payment for the as-constructed survey of EDBs and associated items, including creating the electronic 3D CADD model and report, shall be included in Item 625 Construction Surveying.

Revision of Section 212

Soil Amendments, Seeding, and Sodding

Delete Section 212 of the Standard Specifications for this project and replace it with the following:

Description

212.01 This work consists of application of fertilizer, soil amendments, seedbed preparation, and placing seed and sod.

Substitutions from this specification will not be allowed unless submitted in writing to the Engineer and approved by the Region or Headquarters Landscape Architect.

Materials

212.02 Seed, Fertilizers, Soil Conditioners, Mycorrhizae, Elemental Sulfur, and Sod.

(a) Seed. Seed shall be delivered to the project site in sealed bags tagged by a registered seed supplier conforming to the requirements of the Colorado Seed Act, CRS 35-27- 111(1). Seed used on the project shall not be in the Contractor’s possession for more than 30 days from the date of pickup or delivery on the seed vendors packing slip. Bags which have been opened or damaged before Engineer inspection will be rejected. The State required legal tags shall remain on the bag until opened and the seed is placed in either the drill or hydraulic seeders in the presence of the Engineer. The Engineer shall remove all tags after seed has been planted. Each seed tag shall clearly show the following:

(1) Name and address of the supplier

(2) Botanical and common name for each species

(3) Lot numbers

(4) Percent by weight of inert ingredients

(5) Guaranteed percentage of purity and germination

(6) Pounds of Pure Live Seed (PLS) of each seed species

(7) Total net weight in pounds of PLS in the sealed bag

(8) Calendar month and year of test date

Seeds shall be free from all noxious weed seeds per Colorado Seed Act (CRS 35-17)

Soil Amendments, Seeding, and Sodding prohibited noxious weed seed list.

Weed seed content shall not exceed the requirements in part 7.2 of the Colorado Department of Agriculture’s Seed Act Rules and Regulations.

Seed which has become wet, moldy, or damaged in transit or in storage will not be accepted.

Seed and seed labels shall conform to all current State regulations and to the testing provisions of the Association of Official Seed Analysis. Computations for quantity of seed required on the project shall include the percent of purity and percent of germination.

The Contractor shall store seed under dry conditions, at temperatures between 35°F to 90°F, under low humidity and out of direct sunlight. The Contractor shall provide the location of where seed is stored and access to stored seed locations to the Engineer.

Seed stored by the Contractor for longer than 30 days will be rejected.

(b) Organic Fertilizer.