the banks of fourmile creek are undergoing stabilization efforts utilizing rip-rap and vegetation.

the fourmile creek watershed in central iowa consists of nearly 80,000 acres of urban and agricultural communities. it’s also home to over 80,000 residents. as this population has grown over many decades, this expansive watershed has become increasingly prone to regular flood events.

these reoccurring floods have impacted numerous residents, resulting in frequent evacuations and the costly destruction of property. extensive efforts have been taken by several government agencies to minimize flooding and enhance the overall water quality in the watershed. a seasoned team of engineers and environmental scientists from snyder & associates has been at the forefront of these efforts since 2006. through a multitude of projects, our team has made a significant difference in the health and safety of this critical water system.

updating fourmile creek modeling & assessments

initially, snyder & associates was commissioned to study the fourmile creek watershed to establish an accurate floodplain model to update the significantly outdated federal emergency management agency (fema) maps. our team of environmental scientists and engineers used hydrologic and hydraulic flood models, along with stream assessments, to evaluate the impact of flooding on future development and the impact that development may have on the watershed.

hydrologic methods from previous studies only accounted for current land use while grouping the entire watershed into one basin. our team completed a comprehensive review of both existing and future land use plans to predict potential conditions in hydrologic models. each of these models divided the 118-square mile watershed into individual sectors to provide a more accurate analysis.

peak flow rates developed through modeling were used to predict fourmile creek’s response to flood events of varying magnitude and duration. a profile of the watershed patterns was established to create flood maps utilizing lidar data and arcgis software. these maps provide valuable information by increasing awareness of the likelihood of flooding and ultimately, reducing the devastating impacts floods can produce.

streambank stabilization increases watershed resilience

stream flooding in fourmile creek tributary a prior to stream stabilization improvements.

in addition to extreme flooding issues, fourmile creek has a long history of erosion and poor water quality. many factors, such as above-normal precipitation and runoff volumes, impervious surfaces, and agricultural practices within the watershed contribute to the stream’s degradation and erosion. specifically, two tributaries of the creek located in ankeny — northeast tributary a and southeast tributary b — experienced extensive stream degradation and bank erosion after the 2008 floods and placed many properties and infrastructure at risk.

to address these individual tributaries, our team assessed over 7,400-feet of the stream before proposing improvements that would not only mitigate flooding but also complement the stream’s natural protection, as well. this assessment, along with our intimate knowledge of the watershed, led to sustainable design solutions.

homeowner input, technical assessments, and an evaluation of alternatives were utilized to prepare conceptual designs for both tributaries using an integrated stream restoration approach. this approach provided cost-effective and aesthetic creek restoration through the combination of several techniques including vegetated buffers, toe protection, graded floodplain benches, and weirs. combined, approximately 6,500-linear-feet of the stream was successfully stabilized at the conclusion of both projects.

fourmile creek watershed management authority & stormwater management plan

while the rehabilitation of the two tributaries drastically improved the creek’s overall water quality, additional efforts were necessary to continue mitigating flooding, erosion, nutrient loading, and bacteria issues. to address these problems, local communities created the fourmile creek watershed management authority (fcwma) in 2012. this group focuses on collaborative work to address both flooding issues and water quality. snyder & associates was commissioned to study the region with the intent of improving the understanding of the watershed and preparing a stormwater management plan.

our experts knew that appropriate mitigation had to account for a powerful, meandering alluvial stream that transports significant sediment load. in some cases, extreme events caused substantial channel changes due to high flow, debris jams, erosion, and sediment deposition. toe rock protection integrated with bendway weirs, floodplain benches, and native vegetation buffers were incorporated into the design. additional measures included establishing permanent easements and expanding polk county’s adjacent conservation area which helped diversify stream habitat and increased wildlife access to the water.

this management plan also addresses overall maintenance goals and responsibilities, budgetary costs, and phasing for the full development of the comprehensive system. additionally, potential regulatory tools, grants, and funding opportunities were outlined and adopted by all jurisdictions involved.

fourmile creek greenway master plan

natural vegetation was incorporated during restoration to enhance wildlife ecosystems.

a series of eight watershed goals aimed at reducing flooding and improving water quality were included in the plan to provide guidance. each goal was assigned subgoals and tasks to help track milestones and develop a schedule. the adoption of a greenway system, or master plan, was one of the eight primary goals of the fcwma. this specific goal outlines practices, such as native vegetation re-establishment, stream restoration, and wetland enhancements. the greenway master plan addresses these improvements, as well as potential recreation and education opportunities along approximately 10-miles of the creek.

stakeholder input and thoughtful consideration of multiple elements are essential when 2022世界杯32强预选赛 and implementing a greenway system. during a 世界杯足球比赛预选赛 open house, our team gathered community input for the future of fourmile creek, which helped shape the plan’s objectives.

greenway master plan objectives:

• flood management and water quality
• native habitat protection and management
• define greenway
• make connections
• 世界杯足球比赛预选赛 access and service
• education
• economic development
• implementable steps

the greenway master plan provides a path to transform the current, developed landscape to a more natural state. to start, it’s necessary to move at-risk human life, property, and infrastructure away from the floodplain. in place of the developed landscape, work commenced establishing oxbow wetland connections, construction of a stormwater wetland, and prairie restoration. once completed, this corridor will provide many community benefits including recreation, alternative transportation, improved water quality, habitat conservation, and flood control.

stormwater wetland reduces nutrient overloads & flooding

as the greenway plan expanded, partners of the watershed project saw an opportunity to be proactive in developing a solution to protect the environmentally sensitive fourmile creek. this resulted in a stormwater wetland which once again brought our team on board to provide environmental and stormwater design services.

positioned adjacent to the popular gay lea wilson trail, the stormwater wetland provides a natural means to remove pollutants from stormwater and reduce overall flow rates. as stormwater is captured within the wetland, pollutants are removed naturally through reduced water velocity and increased settling, uptake, and filtering by vegetation.

volume control is a particularly important benefit as there are downstream portions of fourmile creek that have been restored and stabilized, but there are other locations that continue to suffer from severe bank erosion. managing the channel protection volume in the wetland improves overall stabilization efforts to reduce sediment transport.

the stormwater wetland helps to treat and slow down 23 acres of stormwater runoff from an adjacent suburban landscape before entering fourmile creek. improvements like this help to reduce sediment and pollutant loading into the des moines river further downstream, protecting it for years to come.

fourmile creek restoration gives new life to natural areas

for over 15 years, snyder & associates has helped shape implementation efforts across the fourmile creek watershed through both agricultural and urban areas. today, work on the fourmile creek watershed continues with stabilization improvements and 世界杯足球比赛预选赛 education outreach that teach residents how to better take care of our watersheds. the snyder & associates team stands ready to continue providing guidance for this beneficial and forward-looking endeavor.

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fourmile creek watershed encompasses approximately 76.642 acres, covering 120 square miles primarily in polk county.

today, stormwater wetland systems are being created as multi-functional infrastructure components that help regulate flooding, improve water quality, heighten biodiversity, and produce natural amenities for communities. these manmade systems are primarily designed for the purpose of treating stormwater runoff by combining the functions of natural wetlands with the added capacity for temporary water storage.

polk county conservation followed this trend with their decision to build a stormwater wetland and sediment basin forebay to treat runoff from 25-acres of mixed residential, commercial, and agricultural land. previously, this land area directly drained into the environmentally sensitive fourmile creek. the snyder & associates team was brought on board to provide their expert environmental and stormwater design services.

proper 2022世界杯32强预选赛 and design impacts stormwater improvements

the lower fourmile creek area is currently being developed into a greenway and hosts a regional bike trail with plans to feature restored woodlands and pocket parks alongside the stormwater wetland. without precise construction 2022世界杯32强预选赛 , equipment, sequencing, and techniques, however, even a properly designed project is likely to fall short of providing maximum benefits.

to ensure it would function as intended, our team ran detailed hydrologic and hydraulic modeling to accurately size the wetland. this process confirmed it would effectively treat runoff from small, frequent storm events while having the capability to pass large storms without causing damage to the wetland or the adjacent trail. though the site had extreme parameter limitations, our design team achieved a successful stormwater wetland design through persistence and detailed 2022世界杯32强预选赛 .

to reduce stream velocity, meanders were added to the stream throughout the wetland.

as designed, the project diverts stormwater from an adjacent roadway into a forebay basin pool with channel meanders added between them to increase the travel length and provide an extended contact period. this allows the wetland system time to serve its purpose of slowing flows and reducing contaminants. once detained, the stormwater enters a mixture of marsh, shallow-water, and deep-water areas that enhance nutrient removal and provide aquatic habitat for various species.

fourmile creek stormwater wetland qualifies for idals grant

to be approved, designs must match established requirements and meet stakeholder’s criteria while still remaining within the given budget. funding is often a major roadblock to the implementation of innovative and efficient stormwater infrastructure around the country. our team worked hard to match this water resources project with available funding sources.

traditional 世界杯足球比赛预选赛 funding and financing methods for stormwater infrastructure provide limited options to address current problems. at the same time, views on stormwater are changing, with increased recognition of urban flooding and the need for infrastructure to properly manage runoff. prompted by the 2008 gulf hypoxia action plan, iowa took proactive steps to protect and improve its water quality by creating an additional funding source called the iowa water quality initiative. this initiative aims to fund water quality projects that can serve as examples and best practices for cities and individuals.

as one of the multiple cities awarded a portion of the state grant, des moines allocated a percentage of the funds toward the fourmile stormwater wetland project. with this additional funding, the city and the iowa department of agriculture and land stewardship (idals) split project costs, making the overall cost more feasible.

stormwater wetland adds to larger fourmile projects

this project comes as an addition in support of the comprehensive fourmile watershed management plan. the initiative helps outline a series of watershed goals to reduce flooding and improve water quality across the watershed’s 76,600 acres. as this project continues to evolve, new practices are added and retrofitted, helping to enhance water quality across the state of iowa.

our goal is always to deliver a project that makes a positive impact — now and for future generations. after monitoring this stormwater wetland system since completion and recording results indicating an overall improvement in water quality, we’re proud to say that for this project, that goal was completed.

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preventative maintenance ensures sanitary sewers remain in proper working condition and helps prevent potential problems. recognizing the benefits of a proactive approach, the des moines metropolitan wastewater reclamation authority (wra) initiated an evaluation of their trunk sanitary sewer system.

as part of a multi-tiered wastewater collection system, large trunk sewers convey waste to the wastewater treatment plant utilizing smaller tributaries. on this project, the inspected trunk system included sewers installed before 2004. the oldest segments dated back to pre-1960, so the potential for deficiencies was a concern.

through the evaluation, the wra and snyder & associates aimed to establish a baseline for the overall health of the trunk system and use it in creating a wastewater asset management plan.

gis & msi technology assist with sanitary sewer inspection

inspections were conducted in two phases over 18 months. during the first phase, approximately 800 sewer manholes were structurally inspected and assessed for inflow and infiltration (i/i). a geographic information system (gis) network was created to record the results, providing a user-friendly database to locate assets, document maintenance, and reference system conditions. this included all manhole structure inspections with corresponding photographs.

multi-sensor inspection technology utilizes an hd camera, lidar, and sonar to create 360-degree pipe profiles during sewer system assessments.

the field investigation procedure began by assembling wra mapping information for sewers and access structures, along with original construction and as-built drawings. sewer manholes were surveyed utilizing gps to obtain accurate locations. most structures were determined to be in fair to good condition. common issues included cracked or broken mortar seals and chimneys, offset frames, and broken or missing cover bolts.

during the second phase of inspections, nearly 60 miles of gravity sewer (15 inches to 96 inches), 13,000 feet of force main (12 inches to 24 inches), and 7,000 feet of siphon piping were evaluated using multi-sensor inspection (msi) equipment.

for large diameter sanitary sewer trunks and interceptors, a visual-only inspection can be unreliable. with critical usage requirements, it’s not ideal to leave decision-makers with the tough task of evaluating which pipes might appear to be deteriorating. after a variety of inspection technology was considered, msi was chosen for its ability to detect pipe corrosion severity during active flow.

msi creates a 360-degree profile of pipes using a high-definition (hd) camera, lidar, and sonar equipment. the hd camera allows for a detailed visual inspection of each segment and records defects in a nassco pipeline assessment certification program (pacp) database. it also has a photo stitching process that allows the viewer to pan or rotate at any point during an inspection. the lidar information reveals corrosion characteristics to quantify the pipe wall loss of each segment, and sonar collects information from below the water line to tabulate debris volumes and estimate necessary cleaning needs. digital reports and images from the msi provide significant detail to assist in ranking the severity of defects.

risk-based approach to creating a wastewater asset management plan

utilizing the data collected from the inspections, our wastewater engineering team utilized risk analysis methods to assess the health of the network and create an asset management plan for sewer rehabilitation. with costly rehab decisions at stake, risk management is a tool used to prioritize wastewater collection system resources for rehabilitation.

sanitary sewer risk analysis is comprised of two factors—the likelihood of failure (lof) and the consequence of failure (cof).

the lof represents the sewer’s physical condition. the data collected data from the msi was utilized to determine the likelihood of failure for each sewer segment. the likelihood of failure includes two components: overall pipe rating (opr) and corrosion volume per inch diameter-feet. the (opr) is a scoring system that ranks individual pipe segments by the visual defects that were recorded during the inspection. overall pipe ratings by segment are placed in a matrix to calculate the likelihood of failure.

the cof considers the impact on the entire system and surrounding community if a specific segment were to fail. when wastewater utility assets fail without notice, the repair costs are typically exponentially higher when compared to planned rehabilitation. similar to the likelihood of failure, a matrix system is used to assign weights and rate each segment.

by combining both factors (lof and cof) into one (risk), weak points in the system are identified with greater accuracy and more effectively prioritized for repair. this methodology ensures that dollars are spent cost-effectively and rehabilitation schedules are optimized. it also helps prevent environmental and human health implications.

to calculate risk, the lof and cof ratings are multiplied together. wastewater utility assets are prioritized based on the resulting risk rating. risk scores are then sorted from high to low. pipes associated with a higher risk score represent the primary candidates for rehabilitation. once sorting is complete, a curve is generated and risk categories are defined which includes lowest, lower, moderate, higher, and highest risk.

approximately 121 segments (or 20 percent) of the wra’s sewer system were classified as high- to higher-risk assets. the areas that currently present the highest risk lie within the southwest outfall and south side interceptor located south of downtown and parallel to the des moines river. these sewers act as the lifeline of the metropolitan sewer system.

wastewater asset management plan for sanitary sewer system

as a result of the sewer system assessment, two phases of pipelining are recommended. both phases of sewer lining will address several of the highest-risk segments while presenting the best opportunity to meet budget goals. the sewers in this area have particularly flat slopes that result in low velocities and create an ideal environment for corrosive conditions. priority lining will prevent further deterioration of the sewer and ensure that assets are repaired before unexpected failures occur.

the design is currently underway for both phases by the snyder & associates’ team with lining anticipated to be completed in 2021. snyder & associates continues to assist the wra in identifying other areas of priority and 2022世界杯32强预选赛 additional phases of rehabilitation for future programming.

services provided by snyder & associates include construction administration, gis and asset management, gis mapping and analysis, along with wastewater system analysis and 2022世界杯32强预选赛 .

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located west of northwest beaver drive in johnston, camp dodge has been cemented as a community staple for over a century. this military installation where thousands of world war i soldiers once trained now serves as the headquarters for the iowa national guard, iowa’s fire service training bureau, the state police academy, and numerous other organizations.

as the facility has grown over the years, it’s been plagued by well-documented water treatment issues and inefficiencies. based on their desire to own and operate an independent, modern water source with treatment, water storage, and an onsite distribution system, iowa national guard leaders reached out to the duo of 2022足球世界杯小组赛赛程  and snyder & associates to design safe and efficient structural and water system upgrades.

comprehensive water system plan presents viable solutions

the snyder & associates team completed a comprehensive water system master plan to help determine the best course of action moving forward. our 2022世界杯32强预选赛 efforts included the presentation of options for improved water quality with increased capacity and flexibility to meet future demands and regulations. ultimately, the proposed improvements would allow the iowa national guard to serve adequate, reliable, and high-quality water to all camp residents and organizations on the base.

after an extensive review of existing facilities, it was found that raw source water from two shallow groundwater wells contained high levels of iron and total organic carbon (toc), along with small amounts of radium. the team analyzed two treatment alternatives — a lime softening system and an ion exchange process that was similar to the existing plant. detailed equipment sizing plans, functional plan view layouts and elevations, and construction cost estimates for both alternatives were completed. likewise, operational cost estimates for each alternative were provided to aid in determining which alternative would be more economical long-term.

selected lime softening water treatment system & additional upgrades

the lime silo was built to provide storage of lime used in the water softening process. it also houses the lime mixing equipment and the waste lime sludge pumps.

after careful consideration and discussion, the iowa national guard committee authorized the snyder & associates team to proceed with the development of the lime softening water treatment system. this system was viewed as the most versatile treatment option, as well as the best alternative to meet the master plan directives. the lime softening process is able to reduce and/or remove hardness, iron and manganese, arsenic, total organic carbon (toc), and radium from the source water.

to provide system redundancy and allow additional capacity for the future, the final designs included two lime softeners for the facility. additionally, a bulk steel silo for lime storage was included next to the facility. this 20-ton silo provides one-month storage for peak day demand and four-month storage at average day demand.

to further support the new treatment system, an inspection of both source water wells was also recommended. since these systems were built to handle capacities from nearly 60 years ago, it was determined neither well would be able to meet current-day peak demands. our team recommended increasing the overall capacity by upgrading the existing submersible pump, motor, column, discharge piping, valves, and various electrical upgrades. this served as a near-term solution but was the most cost-effective since the expenses associated with a new supply and raw water transmission main were fiscally unachievable at the time.

at snyder & associates, providing solutions that not only overcome immediate obstacles but also consider future expansion needs is at the core of our design process. to that end, much care was taken with the design of the facility’s piping system. our team made sure to create an easily accessible network to accommodate another lime softener in the future if conditions warrant. our piping design can be quickly and easily extended for expansion.

facility upgrades make room for new water treatment systems

completed by our structural engineering team, the building addition for the lime softening equipment was added just to the south of the existing water plant facility. this building also houses the aeration process system, recarbonation, filtration, disinfection, chemical addition, and high service pumping equipment. outside the building, lime sludge lagoons and a 150,000-gallon ground storage reservoir were constructed. in addition, the existing water plant facility was renovated by removing outdated process equipment. this provided space to convert the area into an office, conference room, laboratory, storage area, restroom with shower and lockers, and control room facilities.

interior of chemical feed room during construction completed by 2022足球世界杯小组赛赛程

this ambitious project was completed in multiple phases implemented over several construction seasons to make them financially feasible for the iowa national guard. the updated lime softening water treatment facility has now been operational for a number of years and has continued to meet the needs of all camp residents and organizations on the base.

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established as a training facility for the national guard in 1907, the camp dodge military installation located in johnston, iowa, has seen its share of additions and renovations in over a century of existence. the camp now serves as the headquarters of the contemporary iowa army national guard (iaang) operations, and the over 4,300-acre base maintains many facilities to serve both its military residents, as well as its civilian neighbors. the professionals with snyder & associates and our subsidiary, 2022足球世界杯小组赛赛程 , have partnered with the national guard for over three decades to complete numerous projects of varying size and scope.

repurposing the historic camp dodge pool and surrounding structures

perhaps the largest project our team has undertaken at the camp was the renovation of the former swimming pool area. once billed as one of the largest filtered pools in the country, the camp dodge swimming pool complex closed to the 世界杯足球比赛预选赛 in 2001. the pool opening was filled in with a mixture of sand and soil several years later. the snyder and associates team was tasked with providing landscape architecture services to help renovate the area and create a more useable space.

since the outer coping of the historic pool was still visible, it was repurposed into the design to form the outer border of a multifunctional plaza area. the coping was then surrounded by washed river rock to create a decorative border encircling the space. a portion of the plaza was paved with distinct colored, stamped concrete and paver inserts, adding depth and interest. a free-standing, open pavilion was placed on the southern edge of the plaza. the remaining pool interior space was transformed into a grassy parade ground that can be used for 世界杯足球比赛预选赛 events or military training.

an upgraded parking area was added to accommodate the new space.

updates to the original concession stand created a covered space for grilling and food service, as well as an adjoining patio for outdoor dining. additional parking and walkways were added to support the new functions of the complex and matching exterior finishes were chosen to bring a unified look to the area.

when the basement level of the adjacent camp dodge pool house began to show signs of deterioration several years later, our structural team examined the deficiencies, researched options, and prepared a plan to repair and strengthen the aging concrete foundation. their plan also included moisture mitigation strategies which ensure the structure remains a resource for service members and citizens for many years to come.

athletic training complex provides recreational opportunities

when the idea to incorporate a new athletic training complex was devised in 2019, our team was once again chosen to manage this expansive project. the plan would eventually include a large training building with an indoor field, a soccer field, a softball field, a ½-mile track, and a separate restroom building. due to the size and scope of the plan, our team broke it into five phases. the first phase included the design work and layout of the area, final dimension agreements for each facility, as well as the 2022世界杯32强预选赛 for grading, utilities, irrigation, and seeding. our team also provided design and construction observation services for each stage of the project.

the second phase kicked off with final plans for the large training building and the over 8,000-square-foot indoor turf field and a secure equipment storage area. crews broke ground in december of 2021 with building assembly and interiors to be completed in 2022. the remaining fields and running track will be planned and constructed in subsequent phases.

chapel parking lot expansion, sidewalks, & grounds improvements

the snyder & associates team was tapped again in 2021 to help modernize the chapel building’s access points and parking area. after thoroughly surveying the land to be cleared, our team provided plans and construction documents for the demolition of the current parking area and the removal of aging pavement. additionally, the earthwork and grading were completed for an expanded parking lot, repositioned ada compliant sidewalks, and new gravel access to the rear of the building. this project is also scheduled to be completed in 2022.

our multidisciplinary service offering and our thorough understanding of the iaang’s needs have been gained over three decades of partnership. this knowledge and experience enable us to bring pragmatic solutions to their unique challenges. our firm is proud to partner with the iaang on these projects — and many more to come.

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this expansion project address’ the wastewater treatment needs of ankeny, altoona, bondurant, des moines, and polk county.

the project was separated into five segments with four construction contracts. the project included construction of approximately 16,700-feet of 72-inch and 20,100-feet of 60-inch sanitary sewer through a mix of industrial, commercial, residential, and agricultural areas within the city of des moines and polk county at depths up to 25-feet including open cut and trenchless installation methods. the new sewer primarily paralleled an older sewer/s and an additional project was performed to investigate and evaluate the condition of existing sewers and manholes. this project also included two active railroad crossings requiring significant coordination with the railroad.

with the exception of geotechnical engineering, snyder & associates completed all aspects of the project including comprehensive facility 2022世界杯32强预选赛 , wetland delineation, right-of-way acquisition and negotiations, construction documents, construction observation, construction staking, and construction administration.

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