The existing drop structure in Sand Creek just downstream of the Las Vegas Street Bridge (Las Vegas Drop Structure) was completed around 1998. The drop has failed, which has allowed channel grades upstream and downstream of the drop to roughly equilibrate. The purpose of the project was to protect the channel grade in Sand Creek from experiencing additional degradation by replacing the failed drop structure and restoring channel grades.
Sand Creek at Las Vegas Street serves 53 square miles with a total 100-year discharge of over 25,000 cfs. The sandy soils in and around Sand Creek posed a challenge to curtailing the high-velocity flow of groundwater under the drop structure and to maintaining channel grades around the drop structure in a highly erosive environment. The replaced drop structure needed to remain stable in the 100-year flood and protect against a high degree of seepage and uplift.
The proposed design utilizes a combination of 36” and 48” grouted rock in conjunction with a sheet pile cutoff wall and a large number of weep drains. The 12 feet of elevation drop was broken into three sloping faces to provide hydraulic jumps at two locations for maximum energy dissipation. A low-flow channel within the drop guides perennial base flows through the center of the drop structure. The last sloping face was designed to run below natural grade to accommodate expected degradation in Sand Creek downstream of the drop structure, and a staff gage was integrated into the drop structure to assist the County in monitoring the creek’s erosion.
The project is located in Waters of the U.S. and required Corps of Engineers permit. The project was permitted under Regional General Permit 37 (Stream Stabilization Projects in Colorado).
Las Vegas Street Drop Structure
Approval Agency: El Paso County, USACE
Client: El Paso County
Bret Dilts, (719) 520-6847 Designed: 2018
3275 Akers Drive Design Cost: $105,792
Colorado Springs, CO 80922 Construction: 2018-2019
Construction Cost: $3,300,000
Publicly Funded: Yes
JR Engineering prepared a design for a naturalized stream corridor for a master-planned reach of Second Creek in Commerce City. This project is proposed by the City of Commerce City as part of a multi-stage plan by Mile High Flood District and local governments to restore and improve Second Creek.
Second Creek was historically cut off by two irrigation canals, the O'Brian Canal and the Little Burlington Canal, leaving a 4,000 linear foot section isolated from baseflows, and over time this reach was eventually filled in for agriculture. JR Engineering proposed a naturalized channel design using the 2019 MHFD Second Creek hydrology from the BNSF railroad at the northern end of the site, where a channel exists at the railroad bridge, to the south end of the site where the proposed channel will accept future project phase flows from a Regional Detention Pond and culvert crossing under the O'Brian Canal.
The objectives of the Second Creek North Outfall Channel were to: implement master-planned improvements to Second Creek to achieve the regional rehabilitation objectives; create a naturalized channel for Second Creek where no channel exists due to irrigation canals crossing the historic drainageway path; restore connectivity of Second Creek across the Little Burlington Canal; avoid and minimize impacts to existing wetlands; create and restore wetlands and habitat, making use of the existing hydrology as well as the master-planned developed hydrologic condition; and ensure that the Second Creek channel elevations accommodate a planned crossing of the O'Brian Canal, thereby fully restoring channel connectivity from Denver International Airport to E-470.
The channel design used a three-stage composite channel section with a meandering bankfull channel within a sinuous flood-terrace, all within the existing Second Creek regulatory floodplain. Wetland mitigation was accomplished within the sloping flood terrace, using different wetland ecology for each of the hydroseres, and using off-channel mitigation areas to achieve a 1:1 mitigation ratio.
A proposed bored low-flow pipe under the O'Brian Canal into the Second Creek North Outfall Channel will alleviate the retention pond that had been created on the upstream side of the O'Brian Canal, while still permitting enough ponding in Second Creek for FRICO to maintain their existing 50 cfs diversion into the O'Brian Canal.
The project involved floodplain analysis and the preparation of a CLOMR report to MHFD for consideration of the effects of the project on the overall Second Creek floodplain, which will be impacted by several successive project phases.
Second Creek North Outfall Channel
Approval Agency: Commerce City, MHFD, USACE, FRICO, SACWSD
Reunion Metropolitan District
1790 E Parkside Drive North Designed: 2019-2020
Commerce City, Colorado 80022 Design Cost: $360,415
Contact: Denise Denslow, (303) 288-5431 Construction: TBD
Publicly Funded: Yes (Partial), Public/Private Partnership Construction Estimate: $9,404,500
JR Engineering prepared an update to the overall High Line Canal Operational Hydrologic Model for use in the Urban Drainage and Flood Control District (UDFCD) High Line Canal Master Plan. The High Line Canal is an irrigation ditch that is owned and operated by Denver Water and runs for 67 miles through multiple municipalities. Much of the High Line Canal has adjacent trails and greenbelts, and several watersheds pass through the High Line Canal along its length. Denver Water, in conjunction with UDFCD and its local partners, is permitting stormwater runoff to enter the High Line Canal on a case-by-case basis as they investigate plans to cease their use of the canal for irrigation deliveries.
The original Operational Model was prepared by UDFCD’s consultant as part of the Master Plan in 2017. The Operational Model was intended to be amended and re-evaluated as developments propose discharging to the High Line Canal and as improvements to the High Line Canal are proposed. The hydrologic modeling for the Operational Model was prepared in CUHP/SWMM formats. The purpose of the Operational Model Update by JR Engineering was to examine the feasibility of routing developed conditions stormwater runoff from the proposed Solstice development into the High Line Canal, and to then formally update the Operational Model to include ultimate conditions development throughout the reach.
JR Engineering obtained the Operational Model from UDFCD and modified the sub-catchment delineation and hydrologic parameters to reflect the Solstice development as well as the Sterling Ranch development (by others). The analysis involved a fully developed conditions analysis for existing, proposed, and future development within the watershed and coordination with other developers’ consultants to ensure an accurate representation of the ultimate build-out conditions hydrology. Future conditions drainage patterns and planned conveyance infrastructure designed by others were integrated into the Operational Model Update. Sizing and release rates from proposed and future water quality/detention ponds, both on- and off-site, were included in the modeling effort. The Operational Model established baseline detention requirements for future sub-regional stormwater detention facilities. At the upstream end of the reach, an inflow hydrograph was inserted, which represented the 100-year inflows from the adjacent drainageways and direct discharges from adjacent properties, and was provided by UDFCD’s consultant.
The Operational Model featured several locations where 100-year flows in the High Line Canal would potentially spill into the Solstice development and the adjacent Chatfield State Park. The JR Engineering Operational Model Update analyzed the effects of creating one localized emergency spillway location to Tributary B, an existing drainageway tributary to Chatfield Reservoir. The modeling prompted the design of an overflow inlet box located within the High Line Canal for high flows, and an armored spillway above the inlet box to pass flood-stage discharges to the existing drainageway to reduce the potential for flooding to existing and proposed residences below the Canal. These facilities were fully designed and then incorporated into the Operational Model Update.
The High Line Canal reach adjacent to the Solstice development was designed with side slope modifications and landscape improvements to benefit the linear park aesthetic of the High Line Canal corridor. The existing side slopes were designed to be laid back as compared to the steep banks seen in the existing Canal to promote safety and to turn the Canal into a water feature for the community. These physical changes were integrated into the Operational Modeling Update, which had the effect of creating additional storage volume within the canal corridor and attenuating the routed peak discharge as the inflow hydrograph spread out and occupied the canal’s increased cross-sectional area. The Operational Model Update approval process involved a detention analysis to determine the impacts on the timing of the developed peak discharge in Plum Creek when developed flows are routed in the High Line Canal to Plum Creek.
The Operational Model Update by JR Engineering was approved by UDFCD, Denver Water, and Douglas County.
High Line Canal Operational Hydrologic Modeling Update
Mirabelle Metropolitan District
Contact: Ryan McDermed, (303) 340-3057
9380 Station Street
Lone Tree, CO 80124
Publicly Funded: No Designed: 2018
Agency Approval: UDFCD, Douglas County, Denver Water Design Cost: $14,800
Solstice Offsite Drainage Outfall
Client: Shea Homes
Contact: Ryan McDermed (720) 348-3077
USACE, Colorado Parks & Wildlife, Douglas County
Design Cost: $60,952 Designed: 2017-2019
Publicly Funded: No Construction: 2019
Agency Approval: 2019 Construction Cost: $349,618
The Solstice development is a single-family residential development in Douglas County, located just south of Chatfield Reservoir. Storm drainage from the Solstice site was split between two existing un-named drainageways, both directly tributary to Chatfield Reservoir The main drainageway crossing the Solstice development was termed “Drainageway A” and consisted of over 180 acres of tributary area, which was carried through Chatfield State park where the drainageway was unimproved with the exception of a culvert crossing at the State Park Road with some existing channelization improvements. Changing the existing drainage patterns through the Solstice site was not possible, so JR Engineering coordinated with Colorado Parks and Wildlife and the U.S. Army Corps of Engineers to create a drainage outfall through the State Park to Chatfield Reservoir.
JR Engineering met with the U.S. Army Corps of Engineers onsite and collaboratively decided on an outfall alignment as well as environmentally sensitive areas to avoid. To minimize the effects of development from the Solstice site, JR Engineering designed a Full-Spectrum detention pond at the downstream property line. The pond was designed to over-detain stormwater releases down to a minimum practicable release, and in doing so the outfall pipe was able to be downsized to an 18” pipe from an original 42” required size based on historical peak flows. The outfall pipe was roughly 1,200 linear feet in length, with the remaining 600 linear feet comprised of open channel and two culvert crossings.
The project required a drainage easement through Federal lands, which was accomplished via the Section 408 process. The 408 process also involved a U.S. Fish and Wildlife consultation to evaluate the effects of the project on the Preble’s Meadow Jumping Mouse habitat and nesting birds within the State Park.
JR Engineering prepared an overall basin hydrologic model using EPA SWMM, which took into account the over-detention release from the Solstice onsite detention pond. JR modeled the proposed storm sewer outfall in StormCAD and the open channel segment in HEC-RAS using the calculated 100-year peak stormflows, and evaluated the replacement of the Drainageway A culvert under the State Park road, which was undersized for the tributary stormwater runoff. JR Engineering designed the culvert replacement as well as a low-flow trail crossing for the Chatfield Reservoir perimeter trail.
JR Engineering prepared final construction plans and a final design report that were reviewed and approved by Colorado Parks and Wildlife and the Omaha District of the U.S. Army Corps of Engineers.
JR Engineering prepared hydrologic and hydraulic modeling, to support construction plans and specifications for the Reunion T-88 Regional Water Quality and Detention Pond located in Commerce City. The project involved the conversion of an existing retention pond to detention and water quality meeting current City and UDFCD criteria, which required a thorough analysis of the 700-acre basin’s developed conditions hydrology.
In 2015, the City of Commerce City began addressing the T-88 Basin stormwater outfall to Third Creek as part of the Tower Road expansion project. The conversion of Reunion’s existing retention pond became necessary as part of a public/private partnership and these improvements allow additional development in the watershed. Several alternatives were prepared and cost/benefits were compared so that the City and Reunion could select an alternative. UDFCD was consulted for the alternatives evaluation
JR Engineering prepared an overall CUHP 2.0 model and EPA SWMM model for the ultimate T-88 Basin system using NOAA Atlas 14 point precipitation based on existing and planned development, future offline water quality/detention facilities, and routing of flows through conveyance infrastructure to determine an inflow hydrograph to the proposed T-88 Regional Pond. This hydrology model was integrated into the storm conveyance infrastructure hydraulic model being worked on by the City’s consultant. JR Engineering prepared an overall T-88 Basin hydrology report which allocated water quality and detention needs basin-wide based on planned land use by multiple developers.
The T-88 Pond was then designed using the UD-Detention design aid with the SWMM inflows, and over-detention was provided in the T-88 Regional Pond to utilize existing downstream culverts which were undersized for the T-88 Basin’s future conditions developed discharges.
Reunion T-88 Watershed Hydrologic Analysis
Client: Reunion Metropolitan District
1790 E Parkside Drive North Designed: 2016-2017
Commerce City, Colorado 80022 Design Cost: $120,000
Contact: Denise Denslow, (303) 288-5431 Construction: 2018
Publicly Funded: Yes (Partial), Public/Private Partnership Construction Estimate: $1,700,000
JR Engineering prepared a drainage analysis and construction plans for the Bryant Drive Storm Drain Improvement Project, which involved the removal and replacement of an existing private storm sewer system with a public system having adequate capacity.
Bryant Drive is located within a private mobile home park in Federal Heights. An existing system installed with the development in the 1960s was undersized and at various times the owner has added parallel storm sewer systems to increase its carrying capacity, which in places was comprised of reinforced concrete pipe, PVC pipe, and clay pipe.
JR Engineering evaluated the hydrology of the 41-acre basin and determined inflows at the many storm inlets in the system as well as offsite flows from the Cascade mobile home park and 96th Avenue. An alternatives analysis was prepared which evaluated full or partial replacement of the existing storm sewer system to capture and convey either the 5-year or the 100-year storm event. JR Engineering recommended complete replacement of the old system with the replacement storm sewer designed to capture and convey the 100-year storm event. The proposed replacement system was comprised of a single 42” HDPE pipe down the center of the private roadway, located inside a drainage easement dedicated to the City.
A critical aspect of the design was the decrease in time of concentration and a corresponding increase in piped peak flows resulting from the replacement of the old undersized system with an appropriately-sized replacement, as well as the effects of these larger flows on receiving infrastructure. The selected alternative of a replacement system that conveyed the 100-year event was based on mitigating existing local flooding concerns.
The project is intended to be constructed in 2018 and will include roughly 1,180 linear feet of 42” HDPE storm sewer, 13 manholes, and 415 tons of asphalt.
Bryant Drive Storm Drain Improvement Project
Jeff Hill, PE, CFM
Services: Engineering Designed: 2016-2018
Agency Approval: City of Federal Heights Design Cost: $31,800
Publicly Funded: Yes Construction: 2019
Agency Approval: 2018 Construction Cost: 600,745
The Town of Erie’s 2013 Water Master Plan identified the need for a Zone 3, 24-inch transmission waterline from the existing 16-inch waterline at the intersection of Vista Parkway and County Line Road to the intersection of Vista Parkway and Parkdale Circle. In addition to the new 24-inch transmission waterline, a connection between the new line and an existing 8-inch waterline in Cessna Drive was identified.
The 24-inch transmission waterline is needed to meet the existing and future demand for water supply to the Town’s 1.5-MG and new 4-MG water storage tanks for Zone 3. The connection to the existing 8-inch waterline in Cessna Drive is to eliminate a dead-end water line to improve water quality and supply purposes.
JR Engineering completed the preliminary design phase of the project, which included an analysis of four alternatives for the waterline alignment. Construction schedules, construction cost estimates, pros, and cons were also reviewed for each alignment alternative. The Town ultimately selected an alignment that followed an existing drainage channel and would be less impact on vehicular traffic on Vista Parkway during construction.
After the preliminary design phase, JR completed the topographic survey for the waterline corridor. JR utilized Underground Consulting Solutions (UCS) to pothole 11 existing utilities, which would cross the new 24-inch water line.
JR recently completed the final design and construction documents for the project. The final waterline alignment included 6400 feet of 24-inch PVC waterline, 1600 feet of 8-inch PVC waterline, one bored crossing of the Coal Creek, and two bored crossings of drainage channels. The Town is currently acquiring temporary and permanent easements for the waterline, and construction is anticipated for the winter and spring of 2017.
Client: Town of Erie
Wendi Palmer, (303) 926-2875
Town of Erie Design: 2016
645 Holbrook Street Design Cost: $65,000
Erie, CO 80516 Construction: 2017
Publicly Funded: Yes Construction Cost: $2,500,000
Swan Meadow Village is a small modular home community located in Dillon, Colorado. The community is privately owned and maintained. The existing infrastructure is over 30 years old and requires heavy-duty maintenance. The water lines have been failing and have required costly repairs over the last three or four years. Water to the community is supplied through two-meter vaults, and one meter has failed and has been shut off. With only one point of supply, the entire community has to be turned off anytime repairs have to be made. The water pressure supplied to many of the homes was also very low compared to typical pressure ratings. Water to the community is supplied by the East Dillon Water District.
JR Engineering designed a new water system for the community which included two new water meter vaults with adjustable pressure regulators, new service connections with meters, shut off valves, thermarisers to keep the connections into the homes from freezing during the winter, and three new fire hydrants. The old water system was constructed using ductile iron pipe, and the corrosive soils contributed to the deterioration of the pipe. The water District approved replacing the waterline with PVC and the copper service lines with PVC. During construction, temporary water service was provided to the homes. JR coordinated with the East Dillon Water District, Lake Dillon Fire Department, and Summit County Engineering on this project.
Swan Meadow Village Water Line Replacement – Dillon, CO
Client: Sun Communities
Len Shember (248) 208-2545
Sun Communities, Inc.
27777 Franklin Road, Suite 200
Southfield, MI 48034
Publicly Funded: No
Agency Approval: Design: 2015
East Dillon Water District Design Cost: $45,000
Lake Dillon Fire District Construction: 2016 - 2019
Summit County Engineering Construction Estimate: $1,100,000
JR Engineering prepared the design and construction documents for the initial phase of infrastructure for the 61st and Pena Station project. The 61st and Pena Station development project includes the roadway and utility infrastructure required to serve the first rail stop from Denver International Airport on the east corridor line. The site is located between Tower Road and Pena Boulevard, north of 56th Avenue in the City of Denver.
The sanitary sewer collection system serving the station and adjacent development includes: 1.7 miles of gravity sewer ranging in size from 8-inch to 24-inch, 4.2 MGD sewer lift station, and 0.25-mile force main. The project included preparing a sewer master plan for the nearly 600-acre lift basin. The master plan included a cost-benefit analysis of various locations of the lift station within the three drainage basins to be served. The Lift Station includes; a 40 foot deep wet well; 3-1600 GPM submersible pumps; auxiliary generator, odor filtration system, and controller with telemetry. The station was designed to municipal standards as the City will own and operate the station. Value Engineering was ongoing for the design to keep the station’s budget in line. The station and collection system was approved by Denver Wastewater, Denver Planning, Metro Wastewater, the Colorado Department of Health and Environment, and numerous other jurisdictional agencies.
The goals of the project were to: prepare a cost-effective design for a sewer collection system to serve a 600-acre lift basin supporting the first rail stop from DIA.
61st and Pena Station Phase 1 Sanitary Sewer Improvements and Lift Station
Client: City and County of Denver and Aviation Station North Metropolitan District No. 1
Stewart Williams (CCD) (303)542-7111
Mark Throckmorton (District), (303)295-3071
L C Fulenwider, Inc.
1125 17th Street, Suite 2500 Designed: 2014-2015
Denver, CO 80202 Design Cost: $210,000
Publicly Funded: YES Constructed: 2015-2016
Agency Approval: 2015 Construction Estimate: $2,600,000
JR Engineering prepared the design and construction documents for the Meridian Lift Station H to serve a lift basin within the Meridian Metropolitan District. The lift station will serve 280 single-family homes, 242 units of multi-family, and nearly 200,000 square feet of commercial development at full build-out.
The 0.448 MGD Lift Station includes a 28 foot deep wet well, four 175 gpm submersible pumps, twin 4” force mains, flow metering, wastewater macerator, auxiliary diesel/natural gas generator and controller with telemetry. The station was designed to Meridian Metropolitan District standards as the District will own and operate the station. The station and collection system was approved by Meridian Metropolitan District, the Colorado Department of Health and Environment, Douglas County, Tri-County Health, and the Cherry Creek Basin Water Quality Authority.
JR Engineering provided construction management for the construction phase of the project.
Meridian Lift Station H Improvements
Client: Shea Homes and Meridian Metropolitan District
Ryan McDermed (303) 791-8180
1805 Shea Center Dr., Suite 450 Designed: 2013-2014
Highlands Ranch, CO 80129 Design Cost: $120,000
Publicly Funded: No Constructed: 2015-2016
Agency Approval: 2015 Construction: $1,800,000
JR Engineering provided civil design services for the design associated with the realignment of the Bull Canal to accommodate Washington Street widening and the reconfiguration of the 152nd Avenue Intersection. The design was required to meet the stringent conveyance, maintenance, and hydraulic criteria established by the canal’s management company. The Farmers Reservoir and Irrigation Company (FRICO) managed the canal.
JR’s ability to successfully negotiate with both the City of Thornton and FRICO regarding seepage and design criteria lead to the success of this project.
The realignment of the nearly 1,100-foot segment of the Bull Canal was selected using a multi-tiered alternative analysis using input from numerous entities and stakeholders. The selected alternative replaced outdated bridge structures and utilized a single box structure with radial segments running below the southbound lanes of Washington Street.
Ditch maintenance and ditch rider access where critical requirements for the design of the structure.
JR’s design implemented stilling areas and access locations to address these requirements.
Private irrigation diversion structures are located within the realigned portion of the canal. To make sure that the diversions rates were maintained, the proposed channel geometry was analyzed with the hydraulics. The system hydraulics was modeled and field calibrated under the preconstruction conditions to verify that the proposed design matched the flow depth and velocity parameters.
Bull Canal Realignment at 152nd Avenue and Washington Street
Client: City of Thornton
Pete Brezall, (720) 977-6251
City of Thornton Design: 2013-2020
12450 Washington St. Design Cost: $120,000
Thornton, CO 80241-2405 Constructed: 2020 (Anticipated)
Publicly Funded Construction Estimate: $2.6 Million
Approval Agencies: City of Thornton, Farmers Reservoir and Irrigation Company (FRICO)
The High Line Canal is a 71-mile waterway that provides irrigation and recreational uses across Denver and is managed by Denver Water. JR’s proposed civil design for 4,000 LF of the canal with the Solstice residential development included two roadway crossings over the canal, Lake Breeze Drive & Bright Sky Lane. The new bridge crossings span lengths of approximately 80 feet & 60 feet, respectively. An overflow structure along the canal was also incorporated into the design to prevent the canal from overtopping during major storm events. Recreational trails and maintenance access along the canal were incorporated into the design along with existing canal features.
JR Engineering partnered with ERO Resources Corporation to obtain environmental clearances. A Natural Resources Assessment and Level II Historic Resource Documentation was completed to observe the existing biological resources and identify potential historical impacts associated with the project. The historic resource documentation and public outreach were completed to resolve the possible “adverse effect” of construction near and within the canal identified by the Army Corps and SHPO.
Bridge Structure Selection & Design
A hydraulic analysis was performed on the channel during the design of the bridges & overflow structure. Proposed topography was used to determine the characteristics of the ultimate canal conditions. HEC–RAS & SWMM software was utilized to determine the water surface elevations within the canal at a design flow rate of 600 cfs per the High Line Canal Stormwater Operations Master Plan. JR Engineering worked with San Engineering LLC to create a bridge structure that would not interrupt flows in the canal and provide adequate structural capacity for the given spans. Understanding the above constraints, 32” H x 58” W pre-stressed concrete box girders were selected.
Overflow Structure Design & Hydraulics
Established on the hydraulic analysis of the High Line Canal Operational model, JR Engineering integrated an overflow structure to release any overtopping flow from the canal and prevent flooding of the Solstice Development. The structure was designed to capture runoff that might otherwise overtop the canal and safely route it into the adjacent tributary. The inlet structure is a 4’ x 60’ area inlet built into the slope paving of the canal bank. In the event this inlet capacity is exceeded, there is also an overflow spillway that will route excess into the existing tributary and ultimately Chatfield Reservoir.
Aaron Clutter, PE – Client Manager Garrett Bales, PE, CFM – Director Land Development
Eli Farney, PE, PTOE – Director of Public Works Daniel Clark, PE – Project Lead Engineer
Tristan Bonser, PE – Water Resources Manager
High Line Canal Crossings & Overflow Structure for Solstice Development
Client: Mirabelle Metropolitan District
Contact: Ryan McDermed, (720-348-3077) Designed: 2017-2020
Design Cost: $700,000
Privately Funded: Shea Homes Constructed: 2019-2020
Agency Approval: Douglas County, Denver Water Construction Cost: $13.5 Million
JR Engineering designed the Crystal Valley Ranch Sanitary Sewer Outfall, which included approximately 9,500 linear feet of sanitary sewer to convey wastewater from proposed single-family residential development to an existing interceptor located approximately one mile away. The proposed sanitary sewer line paralleled two existing drainageways, which were undergoing concurrent improvement. The combination of sanitary sewer and drainage channel are located in an open space tract adjacent to a regional trail.
The Crystal Valley Ranch Sanitary Sewer Outfall required an update to the development’s Master Utility Study for updated wastewater loading and pipe sizing, as well as a detailed hydraulic analysis of the system in conformance with the Town of Castle Rock’s Wastewater Collection Design Criteria Manual. The proposed sanitary sewer outfall was reviewed and approved by the Town of Castle Rock.
Crystal Valley Ranch Sanitary Sewer Outfall
Client: Crystal Valley Recovery Acquisition, LLC
Jerry Richmond, (303) 267-6195 Designed: 2014-2016
7200 S. Alton Way, Suite C400 Design Cost: $32,000
Centennial, CO 80112 Construction: 2017
Publicly Funded: No Construction Cost: $360,000
JR Engineering designed improvements on Tanglewood Creek in Westminster which involved stabilizing approximately 0.4 miles of existing natural drainageway following the UDFCD Big Dry Creek Outfall Systems Planning and extending a culvert under 128th Avenue. The channel stabilization measures involved sheet pile check structures and grouted stepped boulder drops for grade control, and fill and realignment of parts of the existing incised Tanglewood Creek channel. All improvements are in the final stages of review by UDFCD and will be eligible for the maintenance program.
The project was analyzed using HEC-RAS and used flow rates from the 2012 Big Dry Creek Flood Hazard Area Delineation report to determine the future conditions floodplain limits and evaluate the hydraulic stability of proposed improvements. The CLOMR and LOMR analysis relied on the FIS flow rates to remap the improved channel.
The CLOMR request involved revised effective, existing, and proposed conditions floodplain mapping with a regulatory floodway analysis. After construction was completed in 2018, a Letter of Map Revision (LOMR) was prepared to officially revise the current Flood Insurance Rate Map (FIRM) to reflect the Tanglewood Creek channel improvements. Also involved in the Tanglewood Creek improvements were coordination for an Individual Permit application to the Army Corps of Engineers for roughly 0.92 acres of impacted jurisdictional wetlands.
The goals of the channel improvement project were to protect existing wetlands and riparian corridors, repair and stabilize eroded reaches of the drainageway, and improve the conveyance of the drainageway to accommodate future basin development.
Tanglewood Creek CLOMR/LOMR
Client: Century Communities, LLC
Mike Cooper, (303) 770-8300 CLOMR: 2015 LOMR:2020
8390 E. Crescent Parkway, Suite 650 Design Cost: $48,000
Greenwood Village, CO 80111 Constructed: 2016-2018
Publicly Funded: Yes (Partial) Construction Estimate: $735,000