240277PRJ Arapahoe Ped Bridge Replacement Ad Plans.pdf

FOR ADVERTISEMENT 7-16-25

FOR ADVERTISEMENT 7-16-25

7/16/25

27/16/25

City of Boulder Transportation & Mobility

FOR ADVERTISEMENT 7-16-25

STORMWATER MANAGEMENT PLAN (SWMP) TEMPLATE LESS THAN 1 ACRE OF DISTURBANCE (6/20/2024)

1. SITE DESCRIPTION

The Contractor shall comply with all CDOT contractual requirements, and all requirements associated with the CDPS-SCP on this project. The SWMP Administrator for Construction shall update the SWMP to reflect current project site conditions.

A. PROJECT SITE LOCATION:

Location or address of construction office:

Project is located in Boulder County and the City of Boulder at the pedestrian bridge on the Path over Boulder Creek adjacent to and on the north side of Arapahoe Avenue (SH7) just west of Cherryvale Road. There will be no on-site construction office.

B. PROJECT SITE DESCRIPTION:

The project includes removal of the existing pedestrian bridge, excavation and construction of new concrete spread footing abutments, setting a new steel truss pedestrian bridge and tying in new concrete path on each approach to the structure. The new bridge is located in the same location as the existing bridge but will be longer to span the existing abutments/retaining walls which will remain in place. There will be no grading activities, utility installation or major landscaping.

C. PROPOSED SEQUENCING FOR MAJOR CONSTRUCTION ACTIVITIES:

First stabilize all areas that are not paved or landscaped through establishment of vegetation cover.

Next, install erosion devices as shown in the plans. Next, install traffic control as shown on approved MHT’s. Then, remove the existing pedestrian bridge and excavate behind the existing abutments/retaining walls. Construct new spread footing concrete abutments on each end and backfill with flowable fill and/or class 1 structural fill. Then install the new pedestrian bridge. Construct the new concrete path approaches to the structure and complete minor edge of path topsoil and seeding. Clean up site and all erosion control devices and remove traffic control.

D. ACRES OF DISTURBANCE:

1. Total area of construction site (LOC): 0.06 acres

2. Total area of proposed disturbance (LDA): 0.02 acres

3. Total area of seeding: 0.002 acres

E. EXISTING SOIL DATA:

The subsurface conditions encountered in the exploratory borings generally consisted of a thin layer of topsoil underlain by exiting fill extending to depths of about 2.5 and 5 feet. The fill was underlain by native granular soils extending to shale bedrock (claystone) at depths of about 8.5 and 11.5 feet.

Data Source(s): Geotechnical Report by Kumar and Associates on 10/12/2021

F. EXISTING VEGETATION, INCLUDING PERCENT OF VEGETATIVE COVER:

During design, the SWMP Administrator for Design in consultation with the Engineer will determine if the SWMP Administrator for Design or the SWMP Administrator for Construction will conduct the Vegetation Transects. If the site is disturbed, an Adequate Reference Site(s) may be utilized, refer to the permit.

Pre-Construction Date of survey: 11/2/2023 Percent Existing Vegetative Cover: 100 Description of existing vegetation: Native grasses on northwest, northeast, and southeast corners of the existing pedestrian bridge Method for determining percent vegetative cover:

Visual Inspection of the areas to be disturbed which showed full coverage of 3 of the 4 corners of the pedestrian bridge with native grasses.

Include a map or table showing transect locations, photos documenting pre-Construction vegetative cover, and methodology used to determine existing vegetative cover to SWMP tab 17:

Post-Construction Date of survey: ______________ Percent Vegetative Cover: ______________ Description of vegetation:

The method used to determine pre-construction percent cover shall be used to determine post construction percent cover.

Include map or table showing transect locations, photos documenting post-Construction vegetative cover, and methodology used to determine existing vegetative cover to SWMP tab 17:

2. STORMWATER MANAGEMENT CONTROLS FOR FIRST CONSTRUCTION ACTIVITIES

THE CONTRACTOR SHALL PERFORM THE FOLLOWING:

A. POTENTIAL POLLUTANT SOURCES

Refer to Potential Pollutant Sources in SWMP Section 4A. Evaluate, identify and describe all potential sources of pollutants at the site in accordance with subsection 107.25 and place any Control Measures required to contain potential pollutants.

B. OFFSITE DRAINAGE (RUN ON WATER):

Place Control Measures to address run-on water in accordance with subsection 208.03.

C. CONSTRUCTION DEWATERING:

Obtain a CDPS Dewatering Permit from CDPHE if conditions of their Low Risk Guidance for Discharges of Uncontaminated Groundwater to Land are not met; see subsections 107.02 and 107.25.

Refer to CDPHE Low Risk Discharge Guidance Document of Uncontaminated Groundwater to Land.

https://www.colorado.gov/pacific/sites/default/files/WQ%20LOW%20RISK%20GW.pdf

D. VEHICLE TRACKING CONTROL:

Control Measures shall be implemented in accordance with subsection 208.04.

E. PERIMETER CONTROL:

Perimeter control shall be established as the first item on the SWMP to prevent the potential for pollutants leaving the construction site boundaries, entering the stormwater drainage system, or discharging to state waters.

Perimeter control may consist of berms, silt fence, erosion logs, existing landforms, or other Control Measures as approved.

3. QUALIFIED STORMWATER MANAGERS:

F. SWMP ADMINISTRATOR FOR DESIGN:

CDOT Certified Individual responsible for developing SWMP Plan Sheets and SWMP Site Maps during the design phase.

Name/Title Contact Information [phone & email] Certification # Kevin Koryto Phone and Email

G. SWMP ADMINISTRATOR FOR CONSTRUCTION:

(As defined in Section 208) The Contractor shall designate a SWMP Administrator for Construction. The SWMP Administrator for Construction shall become the operator for the SWMP and assume responsibility for all design changes to the SWMP implementation and maintenance in accordance to 208.03, the SWMP shall remain the property of CDOT. The SWMP Administrator for Construction shall be responsible for implementing, maintaining, and revising SWMP, including the title and contact information. The activities and responsibilities of the SWMP Administrator for Construction shall address all aspects of the project’s SWMP. (Update the information below for each new SWMP Administrator for Construction) (Copy of TECS Certification must also be included in the SWMP.)

Name/Title Contact Information (phone & email)

TECS Certification # Start Date Engineer Approval

C. PERMANENT STABILIZATION SUBJECT MATTER EXPERT: This qualified individual will be either a Regional Environmental Staff member, or an Independent Contractor Controller (Independent Assurance Program). This expert is a project team leader responsible for ensuring project adherence to requirements of the 207 and 212 Project Special Provisions as follows, and will be available for questions regarding permanent stabilization requirements.

https://www.codot.gov/programs/environmental/landscape-architecture/assets/inspection-and-verification-checklist-for-roadside-revegetation_-111621_v3.pdf]

1. Review the Topsoil Management Plan and the Permanent Stabilization Site Maps.

2. Attend the Environmental Pre-construction Conference.

3. Coordinate the Site Pre-vegetation Conference.

4. Review and recommend approval of products.

5. Review and recommend approval of the Quantities Verification Prerequisite.

6. Attend the Partial Landscape Completion Walkthrough.

7. Attend the Final Landscape Completion Walkthrough.

Name/Title Contact Information [phone & email]

4. DURING CONSTRUCTION

The SWMP should be considered a “living document” that is continuously reviewed and modified. During construction, the following items shall be added, updated, or amended as needed by the Contractor in accordance with Section 208

A. MATERIALS HANDLING AND SPILL PREVENTION:

prior to construction commencing the Contractor shall submit a Spill Prevention, Control and Countermeasure Plan, see subsection 208.06. Materials handling shall be in accordance with subsection 208.06.

B. OTHER CDPS PERMITS:

List applicable CDPS permits associated with the permitted site and activities.

C. STOCKPILE MANAGEMENT:

shall be done in accordance with subsections 107.25 and 208.07

D. CONCRETE WASHOUT:

Concrete wash out water or waste from field laboratories and paving equipment shall be contained in accordance with subsection 208.05.

E. SAW CUTTING:

shall be done in accordance with subsections 107.25, 208.04, 208.05

F. STREET SWEEPING:

shall be done in accordance with subsection 208.04

5. CONTROL MEASURE MAINTENANCE

Maintenance shall be in accordance with subsection 208.04 (f).

6. INTERIM AND PERMANENT STABILIZATION

The Contractor shall comply with all interim stabilization and permanent stabilization requirements in accordance with subsection 208.04(e).

A. SEEDING PLAN

The following seed mix(es) and rates are for drill seeding method as shown on the Permanent Stabilization Site Maps shall be used:

COMMON NAME BOTANICAL NAME LBS. PLS PER

ACRE

Western Wheatgrass Pascopyrum smithii 6.82 Buffalograss Bouteloua dactyloides 9.33 Sideoats Grama Bouteloua curtipendula 1.37 Slender Wheatgrass Elymus trachycaulus 1.16 Blue Grama Bouteloua gracilis 0.32 Green Needlegrass Nassella viridula 0.72 Sand Dropseed Sporobolus cryptandrus 0.01 Showy Milkweed Asclepias speciosa 2.25 Purple Prairie Clover Dalea purpurea 0.25 Sidebells Penstemon/Orchis Beardtongue Penstemon secundiflorus 0.26

Yellow/Upright/Prairie Coneflower/Mexican Hat Ratibida columnifera 0.17

TOTAL 22.66

B. SEEDING APPLICATION:

The following seeding methods shall be used for all areas which are not surfaced and as shown on the Permanent Stabilization Site Maps. Soil compaction shall be minimized for areas where permanent stabilization will be achieved through vegetative cover.

Pay Item Seeding Method (subsection 212.05) Acre 212-00706 Seeding (Native) Drill 0.002

Total 0.002

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.

C. MULCHING APPLICATION:

Apply a minimum of 2 tons/ac of certified weed free hay or 2 1/2 tons/ac of certified weed free straw per acre and in accordance with Section 213, and mechanically crimp it into the soil in combination with an organic mulch tackifier.

Prior to winter shutdown or the summer seeding window closure: Uncompleted slopes shall be mulched with 2 tons of mulching (weed free) per acre, mechanically crimped into the topsoil in combination with an organic mulch tackifier in accordance with Sections 208 and 213.

D. SPECIAL REQUIREMENTS:

Soil amendments, seedbed preparation, and permanent stabilization mulching shall be accomplished within four working days of placing the topsoil on the de-compacted civil subgrades. If placed topsoil is not mulched with permanent stabilization mulch within four working days, the Contractor shall complete interim stabilization methods in accordance with subsection 208.04(e) at no additional cost to the Department.

Permanent stabilization mulching shall be accomplished within 24 hours of hydraulic application of native seed.

The Contractor shall submit a proposed Permanent Stabilization Phasing Plan to the Engineer for approval showing how the SWMP Permanent Stabilization Plans will be implemented to minimize damage to seeded areas.

FOR ADVERTISEMENT 7-16-25

E. SOIL AMENDMENT REQUIREMENTS:

Minimum amendment material requirements for all disturbances to receive seeding (native).

0.002 Total Acres of Seeding (Native) Drill with Topsoil Generated From Topsoil (Offsite)

Se ed in g

(N at iv e)

Dr ill

Pa y

Ite m

-0

06 Pay Item Description Amount/Acre Units Total For This Method

212-00700 Organic Fertilizer High or Low N Pounds 0

212-00701 Compost (Mechanically Applied) CY 0

212-00703 Humate Pounds 0

212-00704 Mycorrhizae Pounds 0

212-00705 Elemental Sulfur Pounds 0

0.00 Total Acres of Seeding (Native) Hydraulic With Topsoil Generated From

Se ed in g

(N at iv e)

Hy dr au lic P ay It em

2-

Pay Item Description Amount/Acre Units Total For This Method

212-00700 Organic Fertilizer High or Low N Pounds 0

212-00702 Biotic Soil Amendments (Hydraulically Applied) Pounds 0

212-00703 Humate Pounds 0

212-00704 Mycorrhizae Pounds 0

0.00 Total Acres of Seeding (Native) Broadcast With Topsoil Generated From

Se ed in g

(N at iv e)

Br oa dc as t

Pa y

Ite m

-0

08 Pay Item Description Amount/Acre Units Total For This Method

212-00700 Organic Fertilizer High or Low N Pounds

212-00701 Compost (Mechanically Applied) CY

212-00703 Humate Pounds

212-00704 Mycorrhizae Pounds

212-00705 Elemental Sulfur Pounds

F. SOIL RETENTION COVERING:

On slopes and ditches requiring a blanket or turf reinforcement mat (trm), the blanket/trm shall be placed in lieu of mulch and mulch tackifier and placed after seeding (native). See SWMP Site Map for blanket/trm locations.

G. PERMANENT STABILIZATION APPLICATION UNDER STRUCTURES:

Under structures shade patterns should be considered and the use of Median Cover Material (Stone) or other stabilized options with an approved Project Special Provision should be used. See SWMP Site Map for locations.

Stabilization will be concrete slope paving

H. RESEEDING OPERATIONS/CORRECTIVE STABILIZATION:

Prior to partial acceptance.

All seeded areas shall be reviewed by the SWMP Administrator for Construction and or Engineer for bare soils caused by surface or wind erosion. Bare areas caused by surface or gully erosion, blown away mulch, etc.

shall be re-graded, seeded, and have the designated mulching applied as necessary, at no additional cost to the project.

7. PRIOR TO PROJECT FINAL ACCEPTANCE

1. When directed by the Engineer, removal and disposal of temporary control measures shall be included in the cost of work.

2. At the end of the project, all ditch checks shall consist of either temporary erosion logs (or equivalent) or permanent riprap.

3. All storm drains shall be cleaned prior to the Final Acceptance of the project. If required, include work in

202-04002 Clean Culvert.

4. Refer to Specification 208.10 for Items to be completed prior to requesting partial acceptance of water quality work

FOR ADVERTISEMENT 7-16-25