X-twitter Spotify Youtube Instagram Facebook Linkedin
Contact

Jackass Gulch MDP FHAD

A concrete drainage channel with a partially submerged metal grate, water pooling behind it, and a patch of ice on the upper surface. The walls are grey and the scene suggests cold weather conditions.
A concrete bridge with metal railings spans over a small stream, surrounded by dry grass, leafless bushes, and a patch of snow; graffiti is visible on the bridge wall.
A concrete bridge with a metal arch underneath spans a shallow creek, surrounded by dry grass and leafless trees, with cars visible on the road above.
A quiet suburban street with double yellow lines, a wooden fence, trees without leaves, and houses in the background on a sunny day. Shadows from trees are cast across the road.
A deep gully cuts through dry, brown grass and leafless shrubs on a hillside. Sparse patches of snow are visible on the ground and in the eroded gully, with bare trees scattered around.
A narrow, shallow creek winds through a dry, barren landscape with leafless shrubs and grasses. Patches of snow remain on the ground, and the sky appears overcast.
A gravel path bordered by a wooden fence curves alongside a river, with leafless trees and shrubs on the left and houses on the right, under a cloudy sky.
A paved footpath with a wooden railing runs alongside a rocky, landscaped area and leafless trees, with buildings visible in the background on an overcast day.
A manhole cover sits atop a mound of cracked, uneven asphalt surrounded by dry, leafless bushes and trees, with patches of snow visible in the background.
A narrow, shallow stream runs between banks of dry grass and reeds, with patches of snow on the ground. Bare trees and overcast skies indicate late winter or early spring in a natural setting.
A small creek runs beneath a crude bridge made of wooden planks and rocks, surrounded by dry leaves, bare branches, and dirt paths in a natural outdoor setting.
A winter scene with patchy snow on the ground, leafless trees, two concrete tunnels, and houses in the background beneath a cloudy sky and distant mountains.
A concrete drainage culvert with metal bars blocking the entrance is partially surrounded by patches of melting snow and dry grass in an outdoor, urban setting.
A dry, grassy field with sparse trees in the foreground, a train passing on elevated tracks in the middle ground, and snow-capped mountains in the background under a partly cloudy sky.
A deep, eroded gully with exposed roots and dry vegetation runs through a grassy field. Patches of snow and dead plants are visible in the foreground, and houses can be seen in the distance.
A large hole in the ground surrounded by dry grass, leafless branches, and patches of melting snow on a chilly, overgrown landscape.
A large drainage pipe surrounded by dry grass and debris is partially blocked by fallen branches and sticks, with sunlight streaming in from the upper left corner.
A narrow creek runs through dry, brown grass and leafless shrubs in winter. Patches of snow are visible on the ground and among the brush, with overcast skies and bare trees in the background.
A dirt path lined with leafless trees and patches of snow winds through a wintery landscape. A sign is posted on the side of the path, and a wooden fence runs along a partially frozen creek.
PROJECT SPONSORS
Logo of the Mile High Flood District, featuring the large blue letters MHFD with a wavy line forming the crossbar of the H, and MILE HIGH FLOOD DISTRICT written below in bold black text.
Follow
Logo for Littleton with a black vertical rectangle and three wavy lines in red, yellow, and white next to the word Littleton in bold black text.
Follow
The Calibre logo features the word Calibre in bold, blue letters with the C and part of the r and e in yellow. Three vertical blue and yellow bars appear to the left of the text.
Follow
A detailed map titled JACKASS GULCH DRAINAGE BASIN MAP (EXISTING CONDITIONS) shows a drainage basin outlined in purple with labeled streets, contour lines, flow arrows, and information tables.
Jackass Gulch was last studied in 1990/1991 alongside Lower Dad Clark Gulch with a FHAD and Outfall Systems Plan (Centennial Engineering, 1990; 1991). The 1990/1991 studies identified significant flood risk at the highly traveled intersection at Santa Fe Dr and Mineral Ave (5+ foot flood depths in the 100-year storm) and proposed several Capital Improvement Projects (CIPs) throughout the watershed. In addition to the 1990/1991 study, the following individual studies have been completed in this area:
  • Phase II Drainage Report for Riverpark Subdivision (Harris Kocher Smith, 2019)
  • Final Drainage Report for Stonecreek Assisted Living & Memory Care (HKS, 2018)
  • Final Drainage Report, RNDC Site (Kimley Horn, 2016)
  • Final Drainage Report and Stormwater Management Plan, Southbridge Shopping Center (Wyatt & Assoc, 2007)
  • Addendum to Phase III Drainage Report for Peakview Office Park (MMC Engineering, 2001)
  • Addendum to Phase III Drainage Report for Peakview Office Park (MMC Engineering, 2001)
  • Final Drainage Report, Centennial Covenant Church (Robinson Dalton, 2001)
  • Phase III Drainage Study for A Part of Lot 1, Southbridge Filing No 3 (Murray Consulting Engineers, 1998)
  • Phase III Drainage Study for A Part of Lot 2, Southbridge Filing No 3 (MMC Engineering, 1998)
  • Phase III Drainage Report, Mineral Avenue Station, RTD Light Rail Transit System (RTD, 1998)
  • Drainage Report, Southwest Corridor Light Rail Transit and Freight Rail Relocation (RTD, 1997)
  • Phase III Drainage Report (Robinson Dalton Consulting, 1996)
  • Phase III Drainage Study for Littleton Apartments at Mineral Avenue (Parsons & Assoc, 1994)
  • Phase III Drainage Study, Southbridge Filing No 9A (Carroll & Lange, 1994)
  • Phase III Drainage Study, Southbridge Filing No 9B (Carroll & Lange, 1994)
  • Phase III Drainage Study for Southpark Subdivision Filing No 11 (Carroll & Lange, 1992)
  • Phase III Drainage Report for the Southbridge Business Park (Fowler & Assoc, 1992)
  • Phase III Drainage Report for Allstate at Southpark Subdivision (Colorado Land Consultants, 1989)
  • Final Drainage Report for South Broadway Car Care Center (Merrick & Co, 1987)
  • Final Drainage Report for Southpark Shopping Plaza (Merrick & Co, 1987)
  • Drainage Report for Jackass Hill Road (KKBNA, 1985)
  • Southbridge Filing No 5, Drainage Study and Erosion and Sediment Control Plan (KKBNA, 1985)
  • Final Drainage Report for Martin Marietta Littleton Systems Center (Merrick & Co, 1983)
  • Southbridge I and II Office Buildings Drainage Study (KKBNA,1981)
  • Drainage Study for Southpark Subdivision (Tir-Consultants, 1981)
  • Viewpoint at Southpark Final Storm Drainage Report (Merrick & Co, 1981)
  • Surface Drainage Report for Mineral Avenue/Atchison Topeka, Santa Fe, and Denver and Rio Grande Railroads Grade Separation Project (Centennial Engineering, 1981)
  • Southbridge Filing No 4 Final Drainage Study (Gingery, 1981)
  • Southbridge Filing 1, Final Drainage Study (Gingery, 1979)

In recent years, Jackass Gulch has experienced significant headcutting, specifically behind residential neighborhoods that abut the Gulch. In addition, planning for development near the intersection of Santa Fe and Mineral has been underway and will be impacted by the stormwater runoff within Jackass Gulch. Finally, the last FHAD was completed in 1990, and there is no FEMA mapped floodplain at Jackass Gulch. As a results of these conditions, the City of Littleton and Mile High Flood District (MHFD, The District) contracted with Calibre Engineering to perform an update of the Master Drainage Plan (MDP) and to either delineate the local floodplain or establish a FEMA Floodplain with an updated Flood Hazard Area Delineation (FHAD).

GOALS
  • Update modeling from 1991 study
  • Verify 1991 study
  • List expected risks and challenge areas
  • Verify and define flood levels at Mineral and Santa Fe intersection
  • Investigate areas of significant headcutting and erosion at upper reaches
  • Investigate options for regional ponds/detention
  • Map floodplain (either local or FEMA) with updated FHAD
  • Investigate/address trash accumulation during large storms
CRITITCAL ISSUES
  • Old models of the Jackass Gulch watershed show 5+ foot flood depths at Mineral and Santa Fe during the 100-year storm. However, this level of flooding has never been witnessed.
  • The 1990 FHAD was completed before the redevelopment of the RTD Park N Ride and Aspen Grove shopping center, which may have significantly changed the flood levels in varying storm events.
  • There is very significant headcutting present at the downstream end of Jackass Gulch, abutting existing neighborhoods. The cause of the headcutting must be identified and mitigated, and Capital Improvement Projects should be identified.
  • Development is underway southwest of Jackass Gulch (immediately southwest of Santa Fe and Mineral). This development will be impacted by storm runoff from Jackass Gulch and may impact the adjacent Platte River. The development plan suggests channelizing flows and incorporating beaver ponds with wetlands. with wetlands.
  • High Line Canal may become available for stormwater conveyance, which could impact the conveyance, functionality, and needs of Jackass Gulch.
  • There is no water quality in this basin.
  • Significant channel stabilization will be required within this watershed.
SCOPE OF WORK
  • Define the watershed and subwatershed boundaries
  • Runoff hydrographs for subwatershed (CUHP) and hydrologic points (SWMM) (2-, 5-, 10-, 25-, 50-, 100-, and 500-year storms)
  • Hydrological inputs for hydraulic models
  • Confirm impacts of regional facilities, irrigation, splitflows, etc.
  • Perform hydraulic modeling and calculations, including site facilities for existing and future (CUHP, SWMM, HECRAS)
  • Analyze effects/impacts of existing detention including water quality detention facilities
  • Integrate structures, surveyed data, surface data and elevations, LOMR, DFIRM, and other resources
  • Calibrate floodplain mapping resulting from future flows
  • Schematic map of changes
  • Compare hydrology with existing CWCB/FHAD/FEMA data
  • Identify and evaluate peak flows (existing and future conditions)
  • Quantify impacts of future development on percent imperviousness
  • Prepare mapping of 100-year floodplain
  • Create floodway and 500-year model, apping, and tabular encroachment table
  • Identify areas of concern
  • Identify wetlands, riparian zones
  • Prepare cost calculations for existing and future infrastructure with FEMA Benefit Cost Analysis Tool
  • ROW determination and cost estimate for land acquisition
  • Develop alternative sketch plans
  • Develop alternatives, determine best alternatives
  • Determine impact of alternatives on water quality in watershed
  • Summary of Operation and Maintenance
  • Detailed cost estimate for best alternatives
  • Feasibility analysis for alternatives
  • Provide survey recommendations for future design
  • Hydraulic and hydrologic studies for selected plan
  • Updated detailed cost estimate for selected alternative
  • Conceptual design for selected alternative
  • Public presentation/community meeting
  • Provide and maintain project website
  • Integrate community input received at public meeting
  • Project management & QA/QC review
  • Agency coordination
  • Utility coordination
NEXT PUBLIC MEETING
A graphic of a calendar page with TBD in yellow at the top and Date Coming in black text below, indicating that the date is to be determined.
project schedule
A vertical project timeline with six phases: Kickoff (Nov 2019), Hydrology (Apr 2020), FHAD (Current), Alternatives (Current), Design (Est. Sept 2021), and Final Report (Est. Dec 2021).
PROJECT MAPS

Jackass Gulch Watershed Map

A detailed map of Jackass Gulch Watershed outlined in purple, showing local streets, waterways, green space, and urban areas, with a legend and labels identifying key features and boundaries.

Jackass Gulch Drainage Basin Map

Jackass Gulch Hydrologic Soils Groups

A map of Jackass Gulch showing hydrologic soil groups. Areas are shaded in pink and green, with labeled sections. Roads, buildings, and water bodies are visible in the background. A legend and scale bar are included.

Jackass Gulch Impervious Surfaces

A map shows impervious surfaces in a suburban area, outlined in purple with numbered sections. Roads, buildings, and a water body are visible. The legend identifies the outlined areas and shaded surfaces. The map is labeled Calibre.

Draft and final reports for Jackass Gulch will be posted here when they are available.

The links below will download PDFs of past plans and reports for this watershed.

Flood Hazard Area Delineation, Lower Dad Clark Gulch and DFA 0068 (Centennial Engineering, 1990)
Outfall Systems Planning for Lower Dad Clark Gulch and DFA 0068 Alternative Evaluation Report (Centennial Engineering, 1990)
Outfall Systems Planning, Lower Dad Clark Gulch and DFA 0068 (Centennial Engineering, 1991)

A contact information table listing names, agencies, roles, phone numbers, and email addresses for personnel from Littleton, MHFD, and Calibre Engineering involved with Jackass Gulch MDP & FHAD.
Contact
X-twitter Spotify Youtube