Attachment E - SWMP.pdf

April 17, 2024 Template Version 1.2

Stormwater Management Plan for:

Sand Creek Trail Improvements Sand Creek Regional Greenway

2700 Peoria St.

Aurora, Colorado 80011

City of Aurora Project No.: 5962A

Owner/Operator(s):

Aurora Parks, Recreation & Recreration

Jessica Schafer

15151 E. Alameda Parkway, Suite 4600

Aurora, CO 80012

(303) 739-7000 jschafer@auroragov.org

Engineer Contact(s):

Loewen Engineering, Inc.

Elysa Loewen, PE

7388 S. Revere Parkway, Suite 601

Centennial, CO

(720) 667-2063 eloewen@loeweneng.com

SWMP Preparation Date: 3/5/2024

Estimated Project Dates:

Project Start Date: 09/24 Project Completion Date: 12/24

APPROVED FOR ONE YEAR FROM THIS DATE

City Engineer

Date

Aurora Water Department

Date JW 06/23/2024

224143ES1-APPREXT1

1958-3004 02E, 01F 02F, 03F

06/25/2024 06/04/2025

“THIS STORMWATER MANAGEMENT PLAN HAS BEEN PLACED IN THE CITY OF AURORA

FILE FOR THIS PROJECT AND HAS BEEN DETERMINED TO COMPLY WITH THE APPLICABLE

CITY OF AURORA STORMWATER MANAGEMENT CRITERIA. ADDITIONAL STORMWATER

MANAGEMENT, EROSION AND SEDIMENT CONTROL MEASURES MAY BE REQUIRED OF

THE OWNER OR HIS/HER AGENTS, DUE TO UNFORESEEN EROSION PROBLEMS OR IF THE

SUBMITTED PLAN DOES NOT FUNCTION AS INTENDED.”

“REVIEW OF THIS PLAN BY THE CITY OF AURORA SHALL NOT IMPLY THAT IT HAS BEEN

REVIEWED FOR COMPLIANCE WITH THE REQUIREMENTS SET FORTH BY THE STATE OF

COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT GENERAL PERMIT FOR

STORMWATER DISCHARGES ASSOCIATED WITH CONSTRUCTION ACTIVITY.”

“SEE APPROVED STORMWATER MANAGEMENT PLAN DESIGN DRAWINGS (SITE PLAN) FOR

SITE SPECIFIC BEST MANAGEMENT PRACTICES.”

Project Owner/Developer Signature Block

I have reviewed the information contained within the Stormwater Management Plan and accept responsibility for the requirements set forth.

Permittee/Affiliation Date

Jessica Schafer/

Landscape Designer at City of Aurora -

Parks, Recreation, and Open Space

Plan Preparer Signature Block

I acknowledge my responsibility for the preparation of the Stormwater Management Plan.

CO Professional Engineer Date

Elysa Loewen, PE / Loewen Engineering

05.29.2024

05.28.2024

FACSIMILE

This electronic plan is a facsimile of the signed and sealed pdf set

Elysa M. Loewen Date 05.28.2024

Table of Contents

SECTION 1 SITE DESCRIPTION

i Site Location ii Description of Adjacent Areas

a) Nature and Purpose of Construction Activity

b) Construction Sequence

c) Area

d) Topography, Soils, and Rainfall Data

e) Existing Vegetation

f) Potential Sources of Pollution

g) Non Stormwater Discharges

h) Receiving Waters

i) Site Features and Sensitive Areas to be Protected

j) Other Applicable Federal, State or Local Programs, Regulations or Restrictions

SECTION 2 DESIGN DRAWINGS

SECTION 3 STORMWATER MANAGEMENT CONTROLS

a) SWMP Administrator and Important Contacts

b) Identification of Potential Pollutant Sources

c) BMPs for Stormwater Pollution Prevention

SECTION 4 FINAL STABILIZATION AND LONG TERM STORMWATER MANAGEMENT

a) Final Stabilization Measures

b) Seed Mix Information

c) Final Stabilization Notes

SECTION 5 INSPECTIONS AND MAINTENANCE

SECTION 6 PROBABLE COST FOR INSTALLATION OF BMPs

SECTION 7 CALCULATIONS MADE FOR THE DESIGN

SECTION 8 VARIANCE REQUESTS

REFERENCES

SWMP APPENDIX A – Floodplain Information

SWMP APPENDIX B – Soils Information

SWMP APPENDIX C – Probable Cost Forms

SWMP APPENDIX F – Vertical and General Construction Matrix

April 17, 2024

"Pursuant to Sections 138-440 and 138-442 of the Aurora Municipal Code, the Permittee shall locate, install, and maintain all Best Management Practices, including, but not limited to, erosion controls, sediment controls, drainage controls, and water quality BMPs as indicated in the approved Stormwater Management Plan (SWMP). The following notes are a requirement and shall be included in the SWMP narrative developed for this project and submitted for approval by the City. BMP installations shall be installed per the COA Standard Detail in effect at the time of installation or per the approved SWMP design drawing, a COA approved variance, or a COA approved design drawing plan amendment."

COA Stormwater Management Standard Notes

1. A City of Aurora Stormwater Quality Discharge Permit for Construction Activities must be issued by the City and executed by a COA Erosion Control staff prior to any earthwork activities.

An on-site inspection will be conducted to verify the correct installation and adequacy of initial

BMPs for the site. No earthwork, including clearing and grubbing, or demolition activities are to begin until the project site has passed an inspection and the City of Aurora Stormwater Quality

Discharge Permit for Construction Activities has been executed. The Permittee is required to present the project’s CDPHE-WQCD Stormwater Discharges Associated with Construction Activity

Permit to the Inspector during the initial inspection. The Permittee shall designate a Stormwater

Management Plan (SWMP) Administrator on the application for the City of Aurora Stormwater

Quality Discharge Permit for Construction Activities. The SWMP Administrator will act as the project representative for any concerns or issues regarding environmental controls and stormwater management.

2. These requirements shall be the obligation of the Permittee, until such time as the Permit is properly closed, or otherwise allowed by the City to be voided, modified, transferred, re-assigned or replaced.

3. This SWMP narrative, the SWMP design drawings, and the Permitte’s inspection and maintenance records are all components of required record keeping and shall be kept on site at all times and updated as required. These and any other pertinent records shall be provided to the City when requested.

4. Any discrepancy between this SWMP and any other approved Stormwater Management Plan for this site shall require compliance with the more restrictive valid, approved plan.

5. Streets shall be constructed with Rough Cut Street Control measures, surface roughened or otherwise temporarily stabilized with rough cut street controls within seven (7) days of completion of grading in the appropriate phase. If paving is to occur within fourteen (14) days after final grading, rough cut street controls shall be waived.

6. Inspection and maintenance of erosion and sediment control Best Management Practices

(BMPs) are the continuous obligations of the Permittee. BMPs shall be inspected at a minimum every seven (7) days and within 24-hours after the end of a precipitation event that produces run-off, and following snowmelt events. If a site is temporarily idle and no construction activities will occur during the 48 hours following a storm event, the post-precipitation event (including

April 17, 2024 snowmelt) inspection shall be conducted prior to commencing construction activities on the site, but no later than 72 hours following the storm event. All necessary maintenance and repairs shall be initiated and completed on an on-going basis, as features are required to operate continuously. Inspections may need to be conducted at a greater frequency than noted above, to ensure features and systems are operating adequately. Erosion and sediment control BMPs shall be maintained and functional for the entire duration of the project.

7. Ingress and egress vehicle access points onto disturbed areas shall be stabilized with Vehicle

Tracking Control Pads (VTC) and shall be constructed with angular rock, 3” to 6” in size and to a depth of at least 9-inches. The use of recycled asphalt or concrete is not permitted. The VTC shall be installed over a liner of non-woven geotextile with a weight of at least 10 oz/yd2 and a grab tensile strength of at least 250 pounds. No dirt or other materials shall be placed on paved surfaces or curb flow lines to act as curb ramps. Only metal ramps or rock wattles may be used in the curb flow line.

8. Fugitive dust emissions resulting from grading activities and/or wind shall be controlled using reasonably available control technology as defined by the Colorado Department of Public Health and Environment.

9. All potential pollution sources on-site shall be identified and control measures installed and practiced to minimize the likelihood of a release. Spill prevention controls shall be developed for the site with BMPs in place to respond to any spills, leaks or other releases.

10. Hydraulic mulching as a means to cover and protect seeding is not an acceptable means of applying mulch in the City of Aurora unless a previously installed irrigation system is used to aid germination and growth and where approved through variance. Hydraulic seeding is not permitted.

11. For all porous landscape detention facilities, in order to prevent clogging of filter medium, installation of the filtration system must be delayed until after the site is fully landscaped.

12. If stockpiles are located within 100 feet of a drainageway or a public storm sewer system, additional sediment controls such as temporary diversion dikes, silt fence, or sediment basin shall be required.

Page Intentionally Left Blank

SECTION 1 SITE DESCRIPTION

In this section, the preparer can gather some basic site information that will be helpful to the permittee later when you file for permit coverage.

– For more information, see City of Aurora Rules and Regulations Regarding Stormwater Discharges

Associated with Construction Activities, current revision (also known as the Rules and Regs), Chapter 2

– Detailed information on determining your site’s latitude and longitude can be found at www.epa.gov/npdes/stormwater/latlong i Site Location

– Site location including, Section, township, range, and latitude/longitude to the nearest 15 seconds.

– Project street location or nearest major cross streets

– If applicable, specific acknowledgement that the land is currently, or will ultimately be owned or managed by the Parks, Recreation and Open Space Department.

Project/Site Name:Sand Creek Trail Improvements

Project Street/Location: 2700 Peoria St.

City: Aurora State: CO ZIP Code: 80011

County or Similar Subdivision: Adams

Latitude/Longitude (Use one of three possible formats, and specify method)

Latitude: Longitude:

1. _ _ º _ _ ' _ _'' N (degrees, minutes, seconds) 1. _ _ º _ _ ' _ _'' W (degrees, minutes, seconds)

2. _ _ º _ _ . _ _' N (degrees, minutes, decimal) 2. _ _ º _ _ . _ _' W (degrees, minutes, decimal)

3. 39.756327º N (decimal) 3. -104.847128º W (decimal)

Method for determining latitude/longitude:

USGS topographic map (specify scale: ) EPA Web site GPS

Other (please specify): Google Earth

Is this land currently or will it ultimately be owned or managed by COA Parks, Recreation, and

Open Space Department? Yes No

CDPS Permit #*:

COA SWQ Permit #*:

*(This is the unique identifying number assigned to your project by your permitting authority after you have applied for coverage under the appropriate construction permit.)

ii Description of Adjacent Areas

– Provide a description of adjacent areas such as residential areas, roads, streams, lakes, etc, which might be affected by the proposed project’s land disturbing activity.

Provide adjacent area information

The proposed Sand Creek Trail Improvement project is in the City of Aurora, north of

Fitzsimons Parkway/ MLK Jr. Boulevard. Peoria Street is partially contained within the project site and passes over the existing trail. The project extends from approximately the City and

County of Denver limits on the west to approximately 750 feet west of the city and county limits. To the north, the project is bound by Sand Creek. The project lies entirely within the

Aurora Parks and Open Space District. Ajacent developments are mixed-use to the south and commercial to the north.

a) Nature and Purpose of Construction Activity Describe of the nature and purpose of the construction activity, note any vertical construction.

The existing Sand Creek Regional Greenway Trail in this location is composed of approximately 1,270 linear feet of 12-foot-wide crusher fines trail. The purpose of the project is to convert the existing crusher fines trail to a 10-foot-wide concrete trail with 3-foot-wide crusher fines shoulder to match the existing paved trail that continues east to the Colorado Front

Range Trail and west where the Sand Creek Regional Greenway Trail/Colorado Front Range

Trail continues into the City and County of Denver. This section of trail was included in a previous conceptual plan in 2020 prepared by Stream for the Mile High Flood District (MHFD) and City and County of Denver (CCOD) but not paved as part of the project.

Residential Commercial Industrial Road Construction Linear

Utility Overlot Grading Over-excavation Vertical Construction

Other (please specify): Pedestrian Trail

b) Construction Sequence The proposed sequence for major activities should be described, including:

– An estimated project start

– An estimated project end date

– The sequence of major construction activities (Initial, interim, final or overlot grading, utilities, vertical, paving, over – excavation, etc.). This is expected to be a brief overview of the project as more detailed phasing information and specific BMPs will be addressed in later sections of the SWMP narrative report.

Estimated Project Start Date: 09/24

Estimated Project Completion Date: 12/24

Describe the major phases of construction:

The first phase of construcion will consist of establishing initial perimeter BMPs. This will consist of construction fence installation, sediment control log installation, installation of inlet protection, designation of a stabilized staging area, installation of tree protection, and placement of vehicle tracking control, and portable toilets. Refer to the attached Grading and Erosion

Control plan for details.

The next phase of contruction will include cut/fill grading operations to establish a base for the concrete trail, following the alignment of the existing trail. Existing crusher fines where concrete trail is proposed shall be removed. Once design cut/fill slopes are established, reconstruction of the existing Sand Creek Trail, including construction of 10' wide concrete trail with 3' crusher fine shoulders shall commence. Also included as part of this phase is to remove and reset an existing 18" RCP passing under the existing trail. All initial construction BMPs will remain in place, and additional BMPs such as Concrete Washout Areas and Inlet protection around newly placed pipe will be installed when associated construction activities occur.

The final phase of construction will consist of final stabilization measures which include seeding and installation of erosion control blankets on all slopes over 4H:1V and seeding of all disturbed areas. Erosion Control Blanket installation can occur immediately after cut/fill slopes are established in order to protect against intermittent erosive rainfall events that might occur during construction. Should any disturbed surface be exposed longer than one week, the contractor shall provide surface roughening as a means of temporary erosion protection until blankets can be installed. Refer to the Grading and Erosion Conctrol plan for seeding and revegetation details. Initial and Interim BMPs may be removed once upstream disturbed areas are stabilized either with vegetation or permanent surfacing.

c) Area The areas for the site should be described including any grading phasing which will need all of the information by phase, as well as for the overall project. This also includes overlot grading in different phases to achieve the outcome of the project. This may be required to be modified by the contractor with a phasing plan submittal.

– Provide estimates of the total area of the site and the sub area within the site expected to undergo clearing, excavation or grading.

– Include an estimate of the excavation and fill volumes involved during the proposed construction.

– Include an estimate of how excavation and fill will be phased.

– Include an estimate of over-excavation areas and volumes (and type) and an estimate of offsite trucking volume (import and/or export).

Note: If exporting material to an area within the COA limits, the receiving site must have its own

SWMP and may be required to have its own COA Stormwater Quality Discharge Permit. If the export site is outside of COA limits, then the requirements of that local jurisdiction must be met and proof of a valid permit for the site will be required.

Total project area:

0.98 acres

Construction site area to be disturbed :

0.98 acres

Export/Import Volume

166 Export CY

Phase Area Cut/Fill Net

Total Project 232 CY cut

66 CY fill

CY

*Note: Cut/Fill numbers listed are approximations

Description of phasing for sites disturbing more than 40 acres.:

N/A

d) Topography, Soils, and Rainfall Data

– Provide a summary describing the soil, the soil type, and hydrologic soil group, permeability, texture, soil erosion potential, depth, soil structure, etc. and potential impacts of the soil type on the quality of any stormwater discharge from the site.

– A description of the topography of the site, existing site conditions, drainage patterns, and existing site slopes should also be included.

Note: A soils map showing the site limits and excerpts regarding the soils information shall be placed in the SWMP narrative report appendices.

Soil type(s):

The United States Department of Agriculture (USDA) Natural Resources Conservation Service and

Soil Survey Geographic Database soil survey map for Adams County was used to determine existing soils on-site. The primary make-up of soil groups is a mix of Ellicott-Glenberg complex

(EgA) to the east and terrace escarpments (Tc) to the west. These soils are classified as Type A and exhibit high susceptibility to erosion from wind and water and high infiltration rates.

Description Result Location of Occurrence

Highest

Elevation:

5342’

Approximately the southwest corner of the site, south of the trail bend to the west of Peoria

Lowest Elevation:

5290’

Within Sand Creek, to the north of the west limit of the trail

Steepest Slope:

33.3%

Slope of the existing hillside to the north, adjacent to the northwest portion of the trail

Average Slope:

7.2%

Average of existing slopes surrounding the existing/ proposed trail location

Slopes (describe current slopes and note any changes due to grading or fill activities):

The project area currently slopes to the north with slopes ranging from about 0% to 33% down to

Sand Creek. All cut and fill slopes will be limited to 3:1 max grades. The proposed trail is designed at 4.5% maximum longitudinal slopes (east to west) for the entirety of the trail. All sections of the proposed trail will not exceed 1.5% cross slope (south to north).

Drainage Patterns (describe current drainage patterns and note any changes dues to grading or fill activities):

The project area drains to the north ultimately entering Sand Creek and continuing east within Sand

Creek channel. This Major Basin in this area is the Sand Creek Basin. The sub-basin defined as part of this project is approximately 6.63 acres in size (Basin A) which includes a portion of Peoria street, the RTD bridge, sand creek, and open space containing the existing crusher fines trail and some existing concrete trail. The proposed trail improvements will maintain the overall historic drainage patterns on the site; some modifications will be made to make improvements to local drainage adjacent to the trail, but minor modifications will be made to the existing trail grade and overall basin size, basin overall slope, and design point will remain unchanged.

Normal Monthly Precipitation Table in Inches

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.51 0.49 1.28 1.93 2.32 1.56 2.16 1.82 1.14 0.99 0.98 0.63

Adapted from: http://www.ncdc.noaa.gov/oa/climate/online/ccd/nrmlprcp.html

Imperviousness and Runoff Coefficients:

― Calculate the percentage of impervious surface area before and after construction

― Calculate the runoff coefficients before and after construction.

Percentage impervious area before construction:

24.6

Runoff coefficient before construction (100 Yr):

0.29

Percentage impervious area after construction:

26.9

Runoff coefficient after construction (100 Yr):

0.31

e) Existing Vegetation

– Provide a description of the existing vegetation at the site and an estimate of the percent vegetative cover density prior to disturbance in an average square yard of the site. This requirement does not encompass hard surfaces or damaged areas. The consultant may have to evaluate vegetation from a nearby area if there has already been disturbance. There may also be drastically different vegetation in areas of the project or prairie dog issues, discuss as appropriate.

– A plan showing the existing major trees (4” diameter trunks and larger), tree masses, and shrub masses should be provided.

Existing Vegetation on the site:

Existing vegetation on the site primarily consists of native grasses with native shrubs and trees scattered throughout the site.

Pre-disturbance vegetation density:

Vegetation density is generally high throughout the entirety of the site, with the highest density existing along the stream banks of Sand Creek. Vegetative density is lowest along the existing crusher fine trail.

Discuss tree protections and removals (reference detail for protection):

The proposed trail is to follow the existing trail alignment; therefore the disturbance to existing vegetation is minimized. Some trees close to construction activities along the trail shoulders will be protected during construction utilizing the COA standard tree protection detail.

f) Potential Sources of Pollution

– Identify and list the proposed location and description of any potential pollution sources anticipated to be used during the project, such as portable toilets, vehicle fueling, grout/cement mixers, storage of fertilizers, paints or chemicals and stockpiles, etc.

– Materials of concern may include, but are not limited to, raw materials, fuels, metallic products, hazardous substances designated under Section 101(14) of the Comprehensive

Environmental Response, Compensation, and Liability Act (CERCLA), any chemical the facility is required to report pursuant to Section 313 of title III of the Superfund Amendments and

Reauthorization Act (SARA), fertilizers, pesticides, ash, slag, sludge concrete washout, paints, solvents, and waste piles.

Note: This is expected to be a brief list with detailed information being addressed in later sections of the SWMP narrative report.

Potential pollutants and sources to stormwater runoff:

Concrete Materials and Concrete Waste Management

Concrete Curing

Demolition and Debris Disposal

Form Oil and Concrete Forms

Grading Operations (clearing, excavating, etc)

Sanitary Waste Management

Soil Stockpiling

Stabilized Staging/Haul Routes

Trash

Utility Excavations

Vehicle and Equipment Maintenance, Cleaning, or Leaks

Trade Name, Material, or Operation Stormwater Pollutants Potential Location

Concrete Materials and

Concrete Waste Management Concrete

Concrete Trail, Staging Area

(CWA location)

Concrete Curing Curing Compound Concrete Trail

Demolition and Debris Disposal Trash, Sediment, various other contaminants

Removal of existing underdrain pipes adjacent to trail

Form Oil and Concrete Forms Form Oil Concrete Trail/Trail forms

Grading Operations (clearing, excavating, etc) Sediment

Trail and slopes adjacent to trail, pipe outfall and inlet locations

Sanitary Waste Management Sanitary Waste Staging Areas

Soil Stockpiling Sediment Staging Areas

Stabilized Staging/Haul Routes Sediment, Fuel, Oil Staging Areas, access to existing/proposed trail, trail

Trash Debris, Bacteria, various chemicals, etc.

Staging Areas

Utility Excavations Sediment, Fuel, Oil Trail and adjacent graded slopes

Vehicle and Equipment

Maintenance, Cleaning, or Leaks

Fuel, Oil, Grease, Chemicals, Hydraulic Oil Staging Areas

g) Non Stormwater Discharges Identify and list the location and description of any anticipated non-stormwater components of the discharge, such as springs (State permit required), potable water for dust suppression, landscape irrigation return flow, pipeline dewatering (i.e. waterline flushing and testing) diverted stream flows, flows from wetlands, firefighting activities, hydrant blow-offs, building power-washing where detergents are not used, construction dewatering of groundwater (State permit required),uncontaminated air conditioning or compressor condensate, foundation or footing drains where flows are not contaminated with process materials such as solvents (State permit may be required), or other discharges specifically authorized by a separate National Pollutant

Discharge Elimination Systems (NPDES) permit or a separate Colorado Discharge Permit System

(CDPS) permit etc. Discharges are those flows that are allowed to leave the site.

― Identify all allowable sources of non-stormwater discharges that are not identified. The allowable non-stormwater discharges identified might include those in the table below.

― Identify measures used to eliminate or reduce these discharges and the BMPs used to prevent those discharges from becoming contaminated.

Check if

Applicable to Site

List of Potential Non-Stormwater Discharges Management of Discharge

Waters used to wash vehicles where detergents are not used

X Water used to control dust Perimeter BMPs (Sediment Control

Logs)

Potable water including uncontaminated water line flushings

Routine external building wash down that does not use detergents

Pavement wash waters where spills or leaks of toxic or hazardous materials have not occurred (unless all spilled material has been removed) and where detergents are not used

Uncontaminated air conditioning or compressor condensate

Uncontaminated ground water or spring water

Foundation or footing drains where flows are not contaminated with process materials such as solvents

Uncontaminated excavation dewatering

Landscape irrigation

Potable water for firefighting activities

Diverted channels or streams

Flows from wetlands

Sanitary sewer/plumbing line testing

h) Receiving Waters List the name of all potential receiving water (s) and the size, type and location of any outfall. If the discharge is to a municipal storm sewer system, then provide the name of that system, the location of the storm sewer discharge, and the ultimate receiving water(s). State whether or not there are wetlands, the 100-year floodplain status (i.e. if the site is within a floodway, near a flood plain or not within a flood zone), if the receiving water is impaired or not, and if there are any stream crossings proposed.

Note: Floodplain maps shall be provided in the SWMP narrative report appendices and shall show the site in relation to the floodplain.

― List the waterbody(s) that would receive stormwater from your site, including streams, rivers, lakes, and wetlands. Describe each as clearly as possible, such as Murphy Creek, a tributary to the Sand

Creek, and so on. Indicate the location of all waters, including wetlands, on the site map.

― Note any stream crossings or stream diversions, if applicable.

― List the downstream storm inlets, storm sewer system or drainage system that stormwater from your site could discharge to and the waterbody(s) that it ultimately discharges to. It is preferred that the waterbodies are listed to a reservoir, Sand Creek, Cherry Creek or the South Platte.

― If any of the waterbodies above are impaired and/or subject to Total Maximum Daily Loads (TMDLs), please list the pollutants causing the impairment and any specific requirements in the TMDL(s) that are applicable to construction sites. Your SWMP should specifically include measures to prevent the discharge of these pollutants.

The site is within the Cherry Creek Drainage Basin: Yes No

The site is within the Aurora Reservoir Drainage Basin: Yes No

Description of receiving waters:

The project lies entirely within the Sand Creek basin, which drains into Sand Creek and ultimately the South Platte River

Description of storm inlets and storm sewer systems:

There are two storm sewers that are proposed within the site area. One system consists of an

18" RCP that carries flows south to north, under a small section of existing crusher fine trail. The RCP daylights with an FES to the north. The second system consists of a 12"

HDPE w/ area drain that also carries flows north to south under the crusher fine trail and outfalls with an FES. In both cases, outfalls discharge towards Sand Creek. Inlet protection shall be placed installed for both systems.

Description of impaired waters or waters subject to TMDLs:

N/A

100- Year Floodplain Status:

According to the Federal Emergency Management Agency (FEMA) Flood Insurance Rate

Map (FIRM), Panel Number 08005C00338K (17 December 2010). The the location of improvements and cut/fill grading operations are within a Regulatory Zone AE floodplain/Floodway. Further Sand Creek is currently under analysis for a Flood Hazard

Area Delineation and the model has been completed in this area and provided to our team.

The floodplain limits in the FHAD (deemed our best available data) were utilized in our cut/fill planing for the area. See floodplain "no impact" memorandum.

Description of wetlands:

Other: N/A

i) Site Features and Sensitive Areas to be Protected

– Describe unique site features including streams, stream buffers, wetlands, specimen trees, natural vegetation, steep slopes, or highly erodible soils that are to be preserved.

– Describe measures to protect these features.

– Include these features and areas on your SWMP design drawings.

All proposed improvements and cut/fill grading operations are outside of any sensitive areas.

However, Sand Creek is between 25' and 300' north of the existing/proposed trail. Therefore, sediment control log is proposed along the entire length of the trail to protect against sediment transport into the these areas. Additionally, as noted in the soils information (Appendix B), the on site soils are comprised of mainly sand and exhibit high suscepetibility to erosion. To minimize soil erosion all cut/fill slopes shall be kept under a 3:1 maximum, and erosion control blanket shall be placed as shown on all slopes exceeding 4:1. Seed and mulch shall be spread over all disturbed areas outside of the concrete trail. Natural vegetation shall be maintained by mitigating the distrubed area outside of the existing trail, and construction fence being installed around trees to be protected. Refer to the Grading Erosion and Sediment Control Plan for

Details.

j) Other Applicable Federal, State or Local Programs, Regulations or Restrictions State any other regulations that are affecting the site (i.e. State CDPHE, Regulation 72, Consent

Decrees, etc).

1) Endangered Species Certification

State whether or not there are any endangered species or critical habitats on or near the site. If so, then describe the impacts and the measures being taken to address that impact and supply documentation in the SWMP narrative report appendices.

Are endangered or threatened species and critical habitats on or near the project area?

Yes No

If yes, describe the species and/or critical habitat and provide reference to other documents as appropriate:

2) Historic Preservation

State whether or not there are any historic sites on or near the site. If so, then describe the impacts and the BMP measures being taken to address that impact

Are there any historic sites on or near the construction site?

Yes No

If yes, describe or refer to documentation that determines the likelihood of an impact on this historic site and the steps taken to address that impact.

SECTION 2 DESIGN DRAWINGS

Approved design drawings shall be kept with the approved narrative report (this document) in the field and must be kept current. See COA Rules and Regs Chapter 3 for more information regarding

Living Documents. For most projects, a series of site maps is recommended. The first should show the undeveloped site and its current features. An additional map or maps should be created to show the developed site or for more complicated sites show the major phases of development.

– SWMP design drawings are required to indicate the types, locations, and extents of BMPs proposed for installation on the project site.

– For more information and requirements, see Rules and Regulations Regarding Stormwater Discharges

Associated with Construction Activities, current revision (also known as the Rules and Regs), Chapter 2

SECTION 3 STORMWATER MANAGEMENT CONTROLS

This section shall describe the stormwater management controls that will be used to control pollutants in stormwater discharge during construction activity.

a) SWMP Administrator and Important Contacts

– List Contact names and phone numbers for the SWMP Administrator, alternates, owner, developer, etc that are known

– Copy as needed

Owner/Operator(s):

City of Aurora Parks Recreation and Open Space Division

Jessica Schafer

15151 E. Alameda Parkway, Suite 4600

Aurora, CO 80012

(303) 739-7000

Area of Control (if more than 1 operator at site):

Project Manager(s) or Site Supervisor(s):

Company or Organization Name: TBD

Name:

Address:

City, State, Zip Code:

Telephone Number:

Fax/Email:

SWMP Administrator Contact(s):

City of Aurora Parks Recreation and Open Space Division

Jessica Schafer

15151 E. Alameda Parkway, Suite 4600

Aurora, CO 80012

(303) 739-7000

This SWMP was Prepared by (the Colorado Licensed

Engineer):

Loewen Engineering

Elysa Loewen

7388 S. Revere Parkway, Suite 601

Centennial, CO 8012

(720) 667-2063 eloewen@loeweneng.com

Emergency 24-Hour Contact (for site, not 911):

Company or Organization Name: TBD

Name:

Address:

City, State, Zip Code:

Telephone Number:

Subcontractor(s):

Company or Organization Name:

Name:

Address:

City, State, Zip Code:

Telephone Number:

Other:

Company or Organization Name:

Name:

Address:

City, State, Zip Code:

Telephone Number:

Other:

Company or Organization Name:

Name:

Address:

City, State, Zip Code:

Telephone Number:

b) Identification of Potential Pollutant Sources All potential pollutant sources, including materials and activities, at a site must be evaluated for the potential to contribute pollutants to stormwater discharges.

– Identify and describe the sources of potential pollutants to stormwater discharges. At a minimum, each of the following sources and activities shall be evaluated for the potential to contribute pollutants to stormwater discharges.

– Numbers in [] brackets indicate the appropriate section to describe the BMPs to be used to address the potential pollutant source

Applicable to Site (Y, N, Maybe)

Sources of Potential Pollutants to

Stormwater Discharges

Applicable to Site (Y, N, Maybe)

Sources of Potential Pollutants to

Stormwater Discharges

Y

All disturbed and stored soils

(including borrow areas, stockpiles, haul routes, and over-excavation)

[Section 3 c) 1, 2, and 3]

N

Routine maintenance activities involving fertilizers, pesticides, detergents, fuels, solvents, oils, etc.

[Section 3 c) 4]

Y

Vehicle tracking controls and clean up [Section 3 c) 6]

On-site waste management practices

(waste piles, liquid wastes, dumpsters, etc.) [Section 3 c) 7]

N

Management of contaminated soils

[Section 3 c) 4]

Y

Concrete truck/equipment washing, including the concrete truck chute, pump truck primary and associated fixtures and equipment [Section 3 c)

7]

Y

Loading and unloading operations

(including access points and protection of existing BMPs)

[Section 3 c) 10]

Dedicated asphalt and concrete batch plants [Section 3 c) 5]

Y

Outdoor storage areas (building materials, fertilizers, chemicals, etc.)

[Section 3 c) 4]

Y

Non-industrial waste sources such as worker trash and portable toilets

[Section 3 c)7]

Y

Vehicle and equipment maintenance and fueling [Section 3 c) 4]

M

Other areas or procedures where potential spills can occur [Section 3

c) 4]

Y Significant dust or particulate generating processes (including haul

Stormwater or groundwater dewatering [Section 3 c) 9]

Applicable to Site (Y, N, Maybe)

Sources of Potential Pollutants to

Stormwater Discharges

Applicable to Site (Y, N, Maybe)

Sources of Potential Pollutants to

Stormwater Discharges routes, masonry mixing, and silos)

[Section 3 c) 2]

N

Power washing of building using detergents or other chemicals/solvents [Section 3 c) 4]

Building/vertical construction

(including paints, solvents, drywall, fire retardant, etc) [Section 3 c) 4, 7, 10]

c) BMPs for Stormwater Pollution Prevention This section of the SWMP narrative report shall include a narrative description of the appropriate controls and measures that will be implemented before, during and after construction activities at the project site to manage and control the runoff of pollutants.

The SWMP narrative report shall clearly describe the relationship between the phases of construction, and the implementation and maintenance of BMP controls and measures. For example, the report must indicate which controls will be implemented during each of the following phases of construction:

clearing and grubbing for perimeter controls, installation of initial BMPs, clearing and grubbing, overlot grading, installation of interim BMPs, site construction, utility construction, vertical construction, other pertinent construction phases, final grading, stabilization, removal of BMPs, and Permit closeout.

1) Structural Practices

– Clearly describe the initial/interim, post-paving, and permanent structural site management practices to control erosion and sediment transport. Practices may include, but are not limited to: silt fences, diversion dikes, temporary slope drains, inlet protection, outlet protection, check dams, curb/rock socks, sediment control logs, compacted earthen berm, and terracing.

BMP Description: Sediment Control Log

Intended Use/Purpose: Sediment control logs shall be installed to the east of the stockpile/ staging area and along the north side of the entirety of the existing Sand Creek Trail that is proposed to get replaced.

Appropriate Installation

Timing:

Sediment control logs shall be installed before removal of existing Sand Creek Trail and prior to grading operations starting.

Appropriate Removal

Timing:

The sediment control logs shall be removed after both the proposed Sand Creek Trail improvements have been poured and are set.

BMP Description: Inlet Protection

Intended Use/Purpose: Inlet protection shall be installed around the inlets of storm sewers that pass under the existing trail to prevent transport of sediment towards Sand Creek by settling sediment out of runoff before entering the inlet.

Appropriate Installation

Timing:

Inlet protection shall be installed prior to any grading operations and before mobilization.

Appropriate Removal

Timing:

Inlet protection shall be removed prior to removal of the storm sewer to the west and replaced after the replacement of the new storm sewer. Inlet protection shall be removed after project completion and final stabilization measures have been implemented on all disturbed surfaces.

BMP Description: Vehicle Tracking Control

Intended Use/Purpose: Vehicle Tracking Control is intended to mitigate tracking of sediment into the roadway from construction traffic leaving the site.

Appropriate Installation

Timing:

Vehicle Tracking Control is to be set up after perimeter BMPs are installed, and prior to grading operations starting

Appropriate Removal

Timing:

Vehicle Tracking Control shall be removed after final stabilization measures have taken place and construction traffic has ceased for the project.

2) Non-Structural Practices

– Clearly describe initial/interim, post-paving, and permanent stabilization practices, including site specific scheduling of the implementation of these practices. Site plans should ensure that existing vegetation is preserved where possible and that all disturbed areas are stabilized. Non-structural practices may include, but are not limited to:

temporary seeding, mulching, temporary sod stabilization, vegetative buffer strips, temporary landscaping, temporary erosion control blankets/matting, temporary soil retention matting, surface roughening, dust suppression, seasonal schedule, and preservation of mature vegetation.

BMP Description: Dust Suppression

Intended Use/Purpose: Dust suppression shall be provided as required during earthwork operations and along all disturbed areas that have not been vegetated or paved with concrete.

Appropriate Installation

Timing:

Dust suppression shall occur as required during construction

Appropriate Removal

Timing:

Dust suppression shall be performed until all disturbed areas have been stabilized with vegetation or final surfacing (i.e. concrete or stabilized crusher fines)

BMP Description: Debris and Trash Cleanup

Intended Use/Purpose: Debris and trash cleanup is intended to keep a sanitary workspace at the construction site entrance to protect against sediment tracking.

Appropriate Installation

Timing:

DTC shall take place throughout the duration of construction operations as needed.

Appropriate Removal

Timing:

DTC shall stop after construction completion and all disturbed areas have been stabilized and construction traffic has ceased.

3) Phase Construction Activity and BMP Implementation

This section shall describe the relationship between the phases of construction, and the implementation and maintenance of BMP controls and measures. For example, indicate which controls will be implemented during each of the following phases of construction:

prior to clearing and grubbing for perimeter controls ( installation of initial BMPs), clearing and grubbing, overlot grading, installation of interim BMPs, site construction, utility construction, vertical construction, other pertinent construction phases, final grading, stabilization, removal of BMPs, and Permit closeout.

― Clearly describe the various phases of construction and the implementation of BMPs to be used during each phase. Examples of project phases may include, but are not limited to, demolition, clearing and grubbing, overlot grading, over-excavation, road construction, utility installations, vertical construction, fine grading, and final stabilization. The description for a particular phase may have sub-phases. For example, the overlot grading of an 80 acre site may have to describe multiple sub-phases for the

40 acre disturbance limitation. Another example would be vertical construction phase may describe sub-phases of the construction such as grading, foundations, framing, finishing, and stabilization. For more information, see Rules and Regs, Chapter 2, Section

2.2.1)

Note: Some construction information may need to be added once a contractor(s) are involved. See the

Manual and below for more information.

Phase Description: Initial Phase

Duration of phase

(start/end dates):

Installation occurs prior to grading operations and terminates after initial BMPs are in place.

BMPs Associated with the Phase:

Construction Fence, Vehicle Tracking Control, Sediment Control Logs, Debris and Trash Cleanup, Inlet

Protection, Portable Toilets

Describe Temp/Final

Stabilization for Phase:

Installation of all perimeter BMPs is complete.

Phase Description: Interim Phase

Duration of phase

(start/end dates):

Interim phase starts as soon as initial BMPs are installed and grading operations commence and ends when proposed grading meets the design intent and is deemed acceptable/ready for stabilization

BMPs Associated with the Phase:

Concrete Washout, Inlet protection for proposed culvert/inlets

Describe Temp/Final

Stabilization for Phase:

Disturbed areas to remain until seeded erosion control blanket can be installed. Construction of proposed improvements is complete.

Phase Description: Final Phase

Duration of phase

(start/end dates):

Installation occurs after proposed construction activities are complete and when the season allows for successful growth of seeded erosion control blanket

BMPs Associated with the Phase:

Erosion Control Blanket, Seeding and Mulching

Describe Temp/Final

Stabilization for Phase:

Erosion control blanket and seeding and mulching will be completed once cut/fill slopes are per design and revegetated.

a. Overlot Grading Specific Practices

Overlot grading specific practices should address items such as: surface roughening, blanketing, terracing, mulching, temporary seeding, permanent seeding, temporary sediment pond construction and removal, phasing, haul routes, disturbance limits, rough cut street controls, etc.

– Address haul routes may be designated on the SWMP updates and shall take into consideration drainage, erosion and sediment control BMPs, along with interim stabilization measures.

– Discuss interim stabilization may be provided via plan amendment by the contractor and the engineer at the Erosion Control Kick Off meeting. These measures shall be provided with timeframes and down gradient controls.

BMP Description: Erosion Control Blanket

Intended Use/Purpose: Erosion control blanket shall be placed on all slopes 4:1 or greater to provide erosion protection prior to vegetation being established

Appropriate Installation

Timing:

The erosion control blanket shall be placed at the completion of final grading, after seeding, and in lieu of mulching.

Appropriate Removal

Timing:

The erosion control blanket shall remain in place through the establishment of vegetation and is not removed.

BMP Description: Seeding and Mulching

Intended Use/Purpose: Seeding shall be placed on all disturbed areas according to the plan and in conjunction with the rolled erosion control products

(no mulching required). All areas will be seeded with an approved seed mix specific to existing upland areas within project limits. This will establish a vegetative cover to limit erosion from disturbed areas.

Appropriate Installation

Timing:

Seeding will be completed at the end of grading operations.

Appropriate Removal

Timing:

Seeding will remain as a permanent BMP.

Temporary drainage BMPs (diversion ditches, sediment traps or sediment basins) shall be maintained at all times.

– Discuss timing and procedural requirements for implementation, maintenance and removal of these items during this period of construction.

b. Vertical and General Construction Requirements – See Appendix for Table of

Required Information

• Staging areas change during construction regularly. Therefore, if “con/conex” boxes are to be utilized and if they are to include liquid pollutants, then a redundant BMP measure must be provided

• Site drainage will need to be maintained during vertical construction. Review conditions to ensure that it will continue to work as shown during the grading/utility timeframes.

• Provide redundant BMPs for generators and mobile concrete washouts to protect from fuel/hydraulic leaks

• Continuously review the down gradient BMPs within the impervious and disturbed areas to ensure that conveyances, inlets and outlets are protected appropriately during this phase.

• Areas of disturbance outside of the building envelope shall still require BMPs.

• Continuously review the timing/phasing of the project to ensure the appropriate

BMPs are implemented as construction continues. Deletion of BMPs shall require different measures to be implemented upon deletion.

• BMPs for keeping impervious surfaces clean may need to be enhanced or added to as construction continues.

• Review and implement BMP measures to control roof drainage. This becomes a point source and may cause extensive erosion on site.

Optional Section – To be included if the items in bullet points cannot be addressed elsewhere in this report.

A Plan Amendment from the contractor shall be required to be submitted to the engineer of record and City of Aurora Water Engineering Plans Reviewer three (3) business days prior to the Erosion

Control Kick-Off Meeting. This submittal shall provide narrative information and the associated details required for vertical construction BMPs (structural and non-structural) that will be implemented during this phase of construction.

• Provide a mixing station detail/area for masonry/brick. If the site is going to bring in silos for masonry mixing, wind protection will be required to minimize the maximum extent practicable the dust from impacting adjacent buildings and streets.

• Saw cutting station detail/area

• Options for handling paints, solvents, glues (i.e. utilize the CWS or provide alternative)

• Provide physical and procedural BMPs for clean up along the building during the installation of brick, stone or stucco

• Access may be required around the building, defining a haul route may be necessary and denote stabilization needs on this proposed haul route

• Address waste handling procedures for drywall, painters, carpet layers etc.

• Stream Diversion Method

• Cranes when access is required around the building and may impact BMPs, relocation may be required

4) Material Handling and Spill Prevention

This section shall describe any procedures and locations for all practices implemented at the site that will be used to minimize impacts from identified potential pollutant sources. BMPs need to address many different pollutant sources that include, but are not limited to exposed storage of construction materials, liquid contaminants, contaminated soils management, fueling procedures, redundant measures for any spill or leak sources, and equipment maintenance procedures. Activities involving potential for spills shall have spill prevention and spill response procedures identified.

– Identify and describe how the sources of potential pollutants to stormwater discharges identified in Section 3.2 will be controlled through BMP selection and implementation. The information provided may address frequency, seasonal considerations, characteristics of the area and surface type, primary and secondary containment, proximity to drainageways and stormwater facilities.

BMP Description: Catch Pan

Intended Use/Purpose: Pans are to be placed under the construction machinery during standard fueling and maintenance procedures to ensure that discharges from the vehicles are collected. In addition, if overnight storing of vehicles is anticipated, vehicles and equipment shall be parked/stored at the Stabilized Staging Area with appropriate spill/clean up measures in place

Location(s) Under machinery on site during fueling

BMP Description: Sediment Control Log

Intended Use/Purpose: Sediment control logs shall be placed along the entirety of the north side of the project area to prevent any discharges from vehicles or pollutants from draining into Sand Creek.

Location(s) The downstream…