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Stormwater Treatment

Stormwater Treatment

Herrera’s scientist and engineers are skilled in the analysis and design of treatment systems and ancillary operations equipment for stormwater runoff.

Our experience has been built from more than 15 years of assistance to municipal clients in the Pacific Northwest. We are experts in the applicable regulatory requirements for treatment and in selecting appropriate and cost-effective treatment technologies that are tailored to the pollutants of concern for the specific application. Our scientists and engineers understand the necessary balance between treatment optimization and operations and maintenance needs.

Additionally, our staff members are experts in the complementary areas of water quality, hydrologic analysis, hydraulic analysis, modeling, permitting, and construction management. Our expertise enables us to provide our clients with practical, well-rounded solutions.

Key Projects

  • South Park Water Quality Improvements Preliminary Engineering Project – Seattle Public Utilities
  • Ecology Embankment Technology Evaluation and Engineering Report – Washington State Department of Ecology
  • Spyglass Stormwater Outfall Water Quality Retrofit Design – Clean Water Services, Oregon
  • Compost Amended Vegetated Filter Strips Pilot Project – Design, installation, and long-term monitoring to provide scientifically defensible justification for use of this relatively low-cost option for treating runoff and reducing runoff volume; Washington Department of Transportation

Pollution Source Control

Pollution Source Control
As part of Herrera’s leading expertise in stormwater management and water quality protection in the Pacific Northwest, we have teamed with public agencies and private industry to provide full service pollution source control support under federal and state National Pollutant Discharge Elimination System permit programs.

Herrera provides engineering evaluation and technical support services to assist public agencies in updating their stormwater management manuals, including source control stormwater requirements, and in performing comprehensive programmatic source control inspections of public works facility operations. We have worked directly with the City of Seattle source control program business and industrial inspection group to support detection inspections of illicit discharges and connections. We service the private sector by providing inspection and auditing support for compliance with National Pollutant Discharge Elimination System stormwater permits throughout Washington and Alaska, specializing in transportation sector industries.

Key Projects

  • Cities of Seattle and Tacoma and Pierce County – Source Control Manual Revisions
  • Illicit Discharge Detection and Elimination – Seattle Public Utilities
  • Stormwater Pollution Prevention Plan Audits and Revisions – Confidential airline client
  • Industrial Stormwater and Wastewater Permit Compliance Assessment – Confidential Client, Tacoma, Washington
  • City-Wide Source Control Assessment – Seattle Public Utilities
  • Stormwater Pollution Control Manual – King County
  • Spill Prevention, Control, and Countermeasures Plan Periodic Inspections – Washington State Department of Transportation

Hydrologic and Hydraulic Modeling

Hydrologic and Hydraulic Modeling
Herrera’s modeling group has extensive expertise with hydrologic and hydraulic modeling.

Our staff works on cutting edge projects for which out-of-the box thinking is required. Herrera conducted a modeling study of a low-impact development subdivision in Seattle, WA at a time when modeling procedures had not yet been developed region-wide. The objectives of the modeling were to support engineering of the stormwater management facilities, including bioretention swales, porous pavement, compost amended soils, and gravel pocket parks; and to predict whether the development would meet state and local regulatory requirements. Our modeling for that project was subsequently included in the flow control modeling section of the Puget Sound Action Team Low Impact Development Technical Guidance Manual for Puget Sound.

Our recent advanced hydrologic and hydraulic modeling studies include dam break analysis, dam enlargement design, design of on-site and regional capital facilities, and development of local and state flow control policy. Our engineers regularly use the following models: HEC-RAS, HEC-GeoRAS, HEC-HMS, XP-SWMM, WWHM2, KCRTS, HSPF, MGS Flood, StormShed, DAM BREAK, Infoworks-CS, and HY8. We also have extensive CAD and GIS capabilities and routinely integrate these technologies into our modeling studies.

Key Projects

  • Low Impact Development Technical Guidance Manual by Puget Sound Action Team, WA – Contributing author
  • High Point Revitalization – City of Seattle, Seattle Public Utilities
  • Ozette River and Lake Ozette Modeling Study of Large Woody Debris – Makah Indian Tribe
  • Thornton Creek Water Quality Channel – Seattle Public Utilities
  • Rainwise Stormwater Incentives Package to encourage onsite low impact development features – Seattle Public Utilities
  • South Park Conveyance Improvements – Seattle Public Utilities

Hydrologic Analysis

Hydrologic Analysis

Herrera has extensive expertise in surface water hydrology and engineering to support a wide range of water resource projects including river reach analyses, regional watershed master planning, design of stormwater flow control and treatment facilities, stormwater planning and design for low impact development projects, wetland studies, flood frequency analyses, and flood risk assessments.

We use continuous simulation hydrologic modeling techniques for small- and large-scale catchments including HSPF, XP-SWMM, Infoworks CS, MGS Flood, WWHM3, KCRTS, and HEC-HMS. We also use single-event modeling techniques as applicable, depending on local regulatory requirements. Single event models regularly used include StormShed, SBUH, and XP-SWMM (event mode).

Key Projects

  • Cispus River Reach Analysis – Lewis County Department of Public Works
  • Bogachiel River Reach Analysis – Washington State Department of Transportation Environmental Affairs Office
  • Manitou Beach Salt Marsh Restoration Feasibility Analysis – City of Bainbridge Island
  • SR 518 Widening – Washington State Department of Transportation
  • Southeast Issaquah Bypass Environmental Impact Statement – City of Issaquah Public Works Department
  • Low Impact Development Technical Guidance Manual by Puget Sound Action Team, WA – Contributing author
  • Lakewood RainCatchers – Pilot project to test cost-effectiveness of rain gardens, vegetated swales, and drainage cisterns; Seattle Public Utilities Engineering
  • High Point Revitalization – Low impact development design support and modeling for urban subdivision/mixed use development; City of Seattle, Seattle Public Utilities
  • Rainwise Stormwater Incentives Package to encourage onsite low impact development features – Seattle Public Utilities

Wastewater Conveyance and Treatment

wastewater conveyance and treatment
Herrera offers engineering and environmental services for wastewater projects ranging from planning and evaluation through design and construction management.

With experience on numerous projects involving wastewater conveyance and treatment systems throughout the Northwest, Herrera engineers provide wastewater characterization process evaluation, facility planning, system design, odor control, contract document preparation, project management, and construction phase assistance from contract administration to inspection. Our conveyance experience includes service area planning, system evaluation and modeling, I/I studies and design of gravity sewers, pumping stations, force mains, and related hydraulic structures. Our treatment experience includes biological processes, solids separation and processing, disinfection, and solids/effluent disposal and reuse. Joining our team of engineers are planners and scientists who provide the permitting, environmental impact assessment, and mitigation expertise required for wastewater projects to meet all regulatory requirements including the Endangered Species Act.

Key Projects

  • King Street Regulator Station and Conveyance Odor Improvements – King County
  • Engineering Services Including Investigation, Planning, Testing, and Analysis for Thurston County Wastewater Processing System – Thurston County Department of Water and Waste Management
  • Brightwater Wastewater Treatment Plant Siting and Conveyance Development – King County
  • South Lake Union Stormwater and Wastewater Discharge Business Case Analysis – City of Seattle
  • Sweyolocken Pump Station Upgrade – King County
  • Soos Creek Conveyance System Improvements Planning – King County
  • Cle Elum Wastewater Facility Plan Environmental Impact Statement – City of Cle Elum

Underwater Investigations and Engineering Inspections

underwater investigations
Herrera’s diving staff conducts underwater scientific and engineering investigations in both navigable and non-navigable waterways using SCUBA and underwater communication technology.

Our underwater diving team consists of a diverse group of certified divers that includes registered professional engineers, certified scientific research and rescue divers, and divers trained in HAZWOPER. Engineering and scientific diving requires specialized equipment and training. Herrera’s diving program includes an in-house dive manual, which complies with WAC 296 -37 Standards for Commercial Diving, WAC 296-37-525 Medical Release (hyberbaric conditions), and WAC 296-37-520 (CPR and First Aid). In addition, our divers are preapproved by the Seattle Department of Transportation for Level 1 and Level 2 underwater surveys.

Herrera divers provide engineering design and construction materials inspection; conduct underwater surveys (bathymetry, sonar, and visual), underwater communications, underwater documentation (underwater video, remote sled video, and digital photography), aquatic plant mapping, macrophyte assessment and removal; and data collection to establish and implement experimental protocols. Herrera divers are familiar with Bridge Inspector’s Training Manual 90, Washington State Bridge Inspection Manual (Underwater), National Bridge Inspection Standards (Underwater), and underwater survey protocols of the Puget Sound Estuary Program.

Key Projects

  • Structural and Operational Assessments of Over 350 Stormwater and Combined Sewer Overflow (CSO) Freshwater and Marine Outfalls – City of Seattle
  • Hylebos Waterway Bridge Rehabilitation Project - Underwater Inspection – City of Tacoma
  • Landsburg Dam Diving Inspection of Spillways – City of Seattle
  • Willow Creek Stormwater Outfall Extension Project – City of Edmonds
  • Underwater Bridge Inspections – City of Seattle

Transfer Stations

Transfer Stations
Herrera’s comprehensive solid waste engineering and planning services include transfer station planning, design, and construction management.

We assist our clients with waste characterization, waste flow projections and modeling, siting studies, incorporating recycling into transfer station design and operations, facility design, construction management, and operations and maintenance plans. We upgrade transfer stations that remain operational during construction, and remediate soil contamination at existing facilities.

Key Projects

  • South and North Transfer Station Fuel System and Drainage Improvements – Seattle Public Utilities
  • Bow Lake Transfer Station Pit Repairs Construction Observation Services – King County
  • Snohomish County Southwest Recycling and Transfer Station Expansion – Snohomish County
  • South Transfer Station Fuel System Design, Site Assessment, and Contamination Removal/Fuel System Installation Oversight – Seattle Solid Waste
  • Algona Transfer Station Safety Improvements Environmental Documentation and Permits – King County
  • Houghton Transfer Station Scale-House and Infrastructure Repairs Project – King County

Solid Waste Management and Design

Solid Waste Management and Design
Herrera’s expertise includes all aspects of waste management planning, siting, design, impact assessment, permitting, and recycling.

Our engineers and planners have a thorough knowledge of applicable local, state, and federal regulations. In addition, Herrera is recognized as a regional expert in policy and economic analysis for recycling, reuse, and product stewardship.

Our engineers design solid waste facilities, conduct waste stream analysis and surveys, and evaluate waste management systems and practices (including environmental best management practices and recycling). We provide environmental assessment; stormwater, leachate and landfill gas systems design and management; site utility engineering; permitting; storm and surface water monitoring, sampling, and treatment evaluation; and construction management services for landfills, transfer stations, and recycling and composting facilities.

Key Projects

  • Solid Waste Facilities Master Plan Support Services – City of Seattle
  • Cedar Hills Regional Landfill Area 6 Closure Design – King County
  • Current Management Practices for Construction and Demolition Debris and Recommendations for Increased Recovery – City of Seattle
  • Engineering Services Including Investigation, Planning, Testing, and Analysis for Thurston County Wastewater Processing System – Thurston County
  • Refocusing Solid Waste Services To Achieve Zero Waste – City of Seattle
  • Solid Waste Disposal Options Evaluations for Landfill Closure at the Alcan Border Station near Tok, Alaska – General Services Administration

Pump Stations

Pump Stations
Herrera offers engineering and environmental services for wastewater projects ranging from planning and evaluation through design and construction management.

With experience on numerous projects involving wastewater conveyance and treatment systems in the Northwest, our engineers provide wastewater characterization, process evaluation, facility planning, system design, contract document preparation, project management, and construction phase assistance from contract administration to inspection.

Our conveyance and pump station experience includes service area planning, system evaluation and modeling, inflow and infiltration studies, and design of gravity sewers, pumping stations, force mains, and related hydraulic structures. Herrera provides civil, mechanical, process, electrical, and instrumentation and control engineering for pump stations from project planning through construction and startup. Herrera engineers have designed pump stations for facilities ranging from 7 mgd to 230 mgd.

Key Projects

  • Sweyolocken Pump Station Upgrade – King County
  • North Creek Pump Station and Storage Facility – King County
  • North Beach Pump Station Replacement Preliminary Design – King County
  • Lakeland Hills Pump Station Evaluation and Design – King County
  • Cedar Hills Regional Landfill Pump Station and Conveyance Improvements – King County
  • Value Engineering Session for the Soos Creek Pump Station – King County
  • Pullen Creek Fish Passage and Restoration Design Project – Taiya Inlet Watershed Council

Landfill Engineering

Landfill Engineering
Herrera’s landfill engineering services include operation planning, engineering, permit assistance, and construction oversight of solid waste landfill development, operation, and closure throughout the Pacific Northwest.

Our expertise includes all aspects of waste management planning, siting, design, impact assessment, and permitting. Our engineers and planners have a thorough knowledge of applicable local, state, and federal regulations. We design solid waste facilities, conduct waste stream analysis and surveys and recycling, and evaluate waste management systems and practices (including environmental best management practices).

Herrera engineers provide landfill gas leachate and engineering services that include operation planning, permit assistance, and construction oversight. Our landfill gas expertise includes all aspects of collection, conveyance, monitoring for operational compliance, monitoring for design basis, gas control, and conformance with Title V air operation. Herrera engineers design active and passive gas collection, conveyance and control systems for landfill sites, remediation sites, and adjacent and ancillary facilities associated or impacted by landfill gas. We have extensive knowledge and expertise working with landfill operations staff to troubleshoot and design retrofits for operation efficiency and gas control. Our construction engineers are knowledgeable in solid waste design and operations to ensure that our designs are efficiently implemented during the construction phase.

Key Projects

  • Cedar Hills Regional Landfill Area 6 Closure Design - King County
  • South Cushman Solid Waste Landfill Expansion - Fairbanks North Star Borough
  • Vashon Landfill Development and Final Closure - King County
  • Carnation Landfill Corrective Action Plan - City of Carnation
  • Engineering Services for Thurston County Leachate Landfill - Thurston County
  • Closure of Municipal Solid Waste Landfill Cell #6 - Fort Lewis Public Works

Design

construction-vasa
Herrera’s interdisciplinary design capabilities include traditional civil design services such as site development, solid waste, wastewater and remediation; innovative stormwater management design tailored to site-specific conditions; as well as restoration design including stream and river restoration, wetland restoration, bank stabilization and estuarine/shoreline design.

All of our designs are based on well tested engineering principles and analysis and extensive knowledge of regulations, codes, and operational considerations.

Key Projects

  • Sweyolocken Pump Station Upgrade – King County
  • Cedar Hills Regional Landfill Area 6 Closure Design – King County
  • South and North Transfer Station Fuel System and Drainage Improvements – Seattle Public Utilities
  • SR 518 SeaTac Airport to I-5/I-405 Interchange Project Hydraulic Analyses and Storm Drainage Systems Design – Washington State Department of Transportation
  • Homestead Creek Residential Low Impact Development Project – Private Developer, Snohomish County, Washington

Conveyance

Conveyance
Herrera’s conveyance design experience includes stormwater conveyance systems and wastewater conveyance systems ranging from small gravity pipelines to large diameter pipelines and force mains.

We offer engineering and environmental services for sanitary sewer projects including monitoring and modeling to support comprehensive planning. Our engineers provide a range of services from flow monitoring and modeling of sanitary sewer systems, to comprehensive planning and design of conveyance systems. Our conveyance experience includes: service area planning; system evaluation and modeling; I/I studies; and design of gravity sewers, pumping stations, force mains and related hydraulic structures.

Joining our team of engineers are planners and scientists who provide the permitting, environmental impact assessment, and mitigation expertise required for wastewater projects to meet all regulatory requirements including the Endangered Species Act.

Key Projects

  • SR 900 Improvements from Newport Way NW to Interstate 90 Stormwater Conveyance Design – Washington State Department of Transportation
  • Soos Creek Conveyance System Improvements Planning – King County
  • Brookside Creek Stormwater Conveyance Outfall Retrofit Design – City of Shoreline
  • Brightwater Wastewater Treatment Plant Siting and Conveyance Development – King County
  • Eastside Interceptor Section 1 Capacity Upgrade – King County

Training Services

Training
Herrera is a Pacific Northwest leader in all aspects of stormwater management, Endangered Species Act (ESA) compliance, environmental documentation, permit compliance, and construction site inspection.

Our staff has provided training programs on these topics for clients including WSDOT, Seattle Public Utilities, Federal Highway Administration, Environmental Protection Agency, and numerous audiences including tribal entities, designers, biologists, and operations and maintenance staff. In addition, our staff members have taught courses for the University of Washington’s Wetland Certificate Program, the Northwest Environmental Training Center, and other universities and community colleges.

All of Herrera’s training services are geared towards interactive formats where the participant is actively engaged in the learning experience, rather than being a passive recipient of the information. Training we deliver is guided in part by Robert Mager’s instructional development methods, as described in his books Making Instruction Work and Preparing Instructional Objectives. We integrate the following three design elements into all course activities, presentations, and instructional methods:

  • Clearly stated instructional objectives.
  • Use of teaching or instructional methods that are appropriate and effective for achieving the stated objectives.
  • Evaluation of measurable instructional results to ensure students have successfully met instructional objectives. (Course evaluations will be relevant to stated instructional objectives.)
  • In addition to the technical expertise and experience as teachers and trainers that we bring to our clients, we also can provide videotaping and editing services and web-based training tools, if those needs arise.

Key Projects

  • Highway Runoff Manual Training Program – WSDOT
  • NEPA Document Review and Training Workshop – Nez Perce Tribe
  • On-Call Environmental Regulatory, Compliance, and Hazardous Materials Training – WSDOT
  • OSHA 8-hour Refresher Training 2002 – U.S. EPA
  • Preparation of Biological Assessments: An Advanced Training Manual – WSDOT

Stream Restoration

Stream Restoration
Herrera’s restoration projects include work in habitats in many of the ecosystems found in the western United States.

Our biologists, geologists, and engineers provide full start-to-finish project services from initial concept planning through site selection, design, and permitting to construction management and post-construction monitoring. Employing a flexible situation-specific approach to each project, our staff creates solutions that best meet our clients’ project and program needs. We specialize in bioengineering techniques that use innovative technologies such as engineered logjams. Our staff develops and implements durable and cost-efficient solutions that successfully integrate into the biological and physical landscape.

Key Projects

  • Aquatic Habitat Restoration Concept Design in Tryon Creek and Lower Columbia Slough – City of Portland
  • Willows Creek Bypass and Stabilization Preliminary Design – City of Redmond, WA
  • Chico Creek Instream Restoration – Kitsap County
  • Pullen Creek Fish Passage and Restoration Design Project – Taiya Inlet Watershed Council
  • Skookum Creek Restoration Plan and Design – Squaxim Island Tribe
  • Lents Interceptor / Johnson Creek Aggradation Project – City of Portland, Bureau of Environmental Services, OR
  • Big Spring Creek (Montana) Remedial Investigation / Feasibility Study – Private Client
  • Bronson Creek (Oregon) Enhancement – Clean Water Services, Oregon
  • Rickreall Creek Restoration Design and Construction Services at the Delbert Hunter Arboretum – City of Dallas, OR
  • Albany Santiam Canal Bank Erosion Project and Canal Operations Plan and Field Assessment – City of Albany, OR

Shorelines

Shorelines
Herrera scientists have a broad range of experience in shoreline master program and critical area protection program updates.

Our scientists are published and have contributed to the scientific literature considered best available science in wetlands, fish habitat, and geomorphology. Shoreline and critical area protection programs require the application of the latest scientific knowledge as it applies to the specific types of natural resources in each jurisdiction.

We provide our clients with innovative solutions to balance the regulation of property with critical areas protection. In addition to assisting jurisdictions in revising regulations, Herrera has worked with jurisdictions to develop programmatic alternatives that would meet requirements for critical areas protection. Herrera has also prepared the SEPA documentation needed for adoption of new plans and regulations.

We have provided inventories of shoreline and critical area resources, including channel migration zones, floodplains, streams, wetlands, and nearshore marine habitat that are integral to science-based planning required by the Growth Management Act to update shoreline and critical areas protection.

We have assisted many jurisdictions and clients with identifying restoration opportunities for wetlands, intertidal areas, rivers, and streams, and has extensive experience implementing restoration projects.

Herrera assisted the National Oceanic and Atmospheric Administration in evaluating the 2003 Shoreline Master Program Guidelines for compliance with the Endangered Species Act. We evaluated how the guidelines would affect development activities in the shorelines of all coastal counties in Washington State. We developed a set of recommendations for local jurisdictions to help ensure compliance with the Act and protection of listed species. Herrera scientists are versed in Ecology’s guidelines for preparing shoreline characterizations for SMP updates and their integration in Critical Area protection.

Our range of local, state, and federal experience related to management, regulation, and protection of shorelines and critical areas makes Herrera uniquely suited to help clients efficiently identify and update their shoreline master program and critical area protection programs.

Key Projects

  • Manitou Beach Salt Marsh Restoration Feasibility Analysis and Preliminary Design – City of Bainbridge Island
  • Frye Cove Bulkhead Replacement Beach Enhancement – South Puget Sound Salmon Enhancement Group
  • Ala Spit Development of Nearshore Process and Habitat Protection Plan – Island County
  • Columbia Slough In-Stream Habitat Enhancement Scoping – City of Portland Bureau of Environmental Services
  • Rockaway Beach Shoreline Road Stabilization Study – City of Bainbridge Island
  • Washington State Shoreline Master Program Guidelines Programmatic Biological Assessment – National Oceanic and Atmospheric Administration Office of Ocean and Coastal Resource Management

River and Floodplain Restoration

River and Floodplain Restoration
Herrera looks at basin-scale processes that affect reach and project site conditions and delivers analysis and recommendations that address issues ranging from threatened infrastructure to degraded habitat.

Our river science and geomorphology group is devoted to restoring rivers and floodplains for future generations. We provide environmentally sensitive alternatives for protecting infrastructure and property and restoring habitat. Herrera’s interdisciplinary staff addresses the complex issues associated with river engineering and restoration, including detailed quantitative analysis and hydraulic modeling; biological assessments and restoration plans; determining channel migration zones; design, specifications, and cost estimates; construction management; and long-term project monitoring. Our clients benefit from designs based on state-of-the-art science and engineering that meet permitting requirements.

Key Projects

  • Gales Creek and Tualatin River Dike Stabilization Project – Clean Water Services
  • South Fork Nooksack River Refuse Site Project – Nooksack Indian Tribe
  • Lower Tolt River Floodplain Reconnection Project – Seattle Public Utilities
  • Auburn Narrows Floodplain Habitat Restoration Project – King County
  • Emergency Response for Nisqually River Erosion Control and Channel Migration in Mount Rainier National Park – National Park Service

Geomorphology and River Science

Geomorphology and River Science
Herrera’s scientists look at basin-scale processes that affect reach and project site conditions and deliver analysis and recommendations that address issues ranging from threatened infrastructure to degraded habitat.

Our river science and geomorphology group is devoted to restoring rivers for future generations. We provide environmentally sensitive alternatives to protecting infrastructure and property. Our interdisciplinary staff addresses the complex issues associated with river engineering and restoration, including detailed quantitative analysis and hydraulic modeling; biological assessments and restoration plans; design, specifications, and cost estimates; construction management; and long-term project monitoring. Our clients benefit from designs based on state-of-the-art science and engineering that meet permitting requirements.

We take restoration projects from planning and analysis through design, permitting, and construction.

Key Projects

  • White River Bypass Reach Hydraulic and Geomorphic Analysis of Flow Diversion – Puyallup Tribe of Indians, Fisheries Division
  • Geomorphic Assessment of the Grays River Watershed – Bonneville Power Administration
  • Cispus River Geomorphic Reach Analysis – Lewis County
  • White River Reach Analysis and Emergency Response Action Plan for Route 410 – WSDOT
  • South Fork Nooksack River / Lower Hutchinson Creek Geomorphic Assessment, Restoration Plan, and Design – Nooksack Indian Tribe Natural Resources Department and the Lummi Nation

River Engineering

construction-vasa
Herrera develops innovative technologies such as engineered log jams (ELJs) to restore habitat and protect infrastructure. Our clients benefit from designs based on state-of-the-art science and engineering. Our ecologically focused designs meet permitting requirements and lead to construction that exceeds regulatory standards.

Engineered log jam (ELJ) technology emulates natural riverine processes to protect roadways and property in a way that provides net environmental benefit. ELJs offer a realistic alternative to traditional engineering practices such as rock riprap, and ELJs are more likely to achieve regulatory approval. We design ELJ applications for rivers of all sizes and freshwater and marine shorelines. ELJ designs have been successfully applied in urban and rural settings throughout regions in the U.S. and Australia. We collaborate with clients to ensure design safety and stability specific to the geographic and regional requirements of the project site.

Our Hoh River project won an American Council of Engineering Companies Gold Award and withstood extreme flows in 2006 flooding.

Key Projects

  • Hoh River Logjam Design and Construction Services at U.S. Highway 101 – WSDOT
  • Dungeness River Engineered Logjam Restoration – Jamestown S’Klallam Tribe
  • South Fork Tolt River Large Woody Debris Placement Project Plans and Implementation – Seattle Public Utilities
  • Design, Consultation, and Inspection of Three Engineered Logjams on the White River – Northwest Pipeline Corporation
  • Quilcene River Engineered Logjam Installation Pilot Project Design and Construction Oversight – Skokomish Indian Tribe

Coastal Engineering Services

Coastal Engineering Services
Herrera’s services range from planning and analysis through design to post-construction monitoring. For our coastal engineering projects, we have a track record of integrating multiple disciplines including engineering, geology, ecology, water resource science, and planning to arrive at successful solutions for our clients.

We conduct coastal engineering projects and studies in shore-drift direction analysis, longshore sediment transport studies, coastal erosion, sedimentation and sediment budget studies, coastal geomorphology analysis, tidal prism modeling and analysis, inlet stability analysis, beach armoring impact assessment, and habitat restoration design.

Our engineers and scientists have project experience in coastal and tidal marsh geomorphology, hydrology, and hydraulics; wave and tidal hydraulics; design and assessment of shoreline structures; underwater monitoring and inspections; wave and boat wake analysis; and analysis, design, and construction services for restoration projects in coastal and estuarine environments.

Key Projects

  • Simonson Boat Ramp and Outfall: Coastal Process Assessment, Biological Assessment, and Permitting Assistance – Island County
  • Tide Marsh Restoration for Lund’s Gulch – Sound Transit
  • Beach Sediment Survey of Puget Sound Shoreline in Thurston County – Thurston County Regional Planning Council
  • Private Property Geomorphic Assessment and Mitigation Project – Private client
  • US Highway 101 Willapa River Potter Slough Hydrologic and Hydraulic Analysis – WSDOT

Lake and Aquatic Plant Management

Lake and Aquatic Plant Management
Herrera SCUBA divers mapped aquatic plants and eradicated Eurasian watermilfoil in Walsh Lake in Seattle’s Cedar River Municipal Watershed.
Herrera’s scientists and engineers have studied and characterized numerous lakes throughout the Pacific Northwest region for the past 26 years, and have applied this extensive background to develop and implement strategies for lake and aquatic plant management.

Our multi-disciplinary staff incorporates scientists, environmental engineers, fisheries biologists, and planners in lake and aquatic plant management projects. These professionals have extensive experience with various lake and aquatic plant projects, primarily focused in the Pacific Northwest region. Our expertise in lake and aquatic plant management includes the following types of projects:

  • Developing lake monitoring plans for diagnostic and restoration studies
  • Developing water quality and stormwater management plans for lake basins
  • Monitoring lakes to evaluate water quality conditions in pelagic (deep) and littoral (nearshore) waters
  • Monitoring surface and groundwater inflows to lakes during base and storm flow conditions for pollutant loading assessments
  • Using scuba divers for underwater videography and structural inspections and to collect sediment cores, aquatic plant samples, and periphyton samples
  • Calculating internal phosphorus loading in lakes using data collected from sediment cores, sediment traps, diurnal water quality studies, and aquatic plant surveys
  • Evaluating sediment contaminant data for dredging projects
  • Collecting and analyzing inflow, outflow, lake stage, precipitation, and evaporation data for hydrologic studies
  • Developing lake water and phosphorus budgets using simple and complex models
  • Evaluating phytoplankton, zooplankton, periphyton, and benthic invertebrate communities for lake restoration projects
  • Evaluating sources of taste and odor and disinfection byproduct precursors in drinking water reservoirs
  • Evaluating pollutant impacts to lakes from nonpoint and point sources
  • Conducting aquatic plant surveys, producing plant distribution/density maps, analyzing biomass and nutrient content, and identifying exotic plant species
  • Preparing exotic species prevention plans and aquatic plant control plans, and surveying lakes for the presence of non-native, invasive aquatic plant species
  • Controlling and eradicating Eurasian watermilfoil and other aquatic plant populations using bottom barriers and hand pulling by scuba divers.

Key Projects

  • Green Lake Restoration Analysis and Alum Treatment Projects – Seattle Parks and Recreation
  • Phase I and II Water Quality Studies, Phosphorous Budget Development, Periphyton and Macrophyte Sampling, Aquatic Plant Surveys, Exotic Aquatic Species Prevention Program, and Taste and Odor Control Plan for Lake Youngs – City of Seattle
  • Walsh Lake Aquatic Plant Survey and Milfoil Eradication Program – City of Seattle
  • Twin Lakes Water Quality Monitoring and Aquatic Plant Assessment – Twin Lake Homeowners Association
  • Chester Morse Reservoir Contaminant Spill and Transport Study – City of Seattle
  • Pine Lake Management Plan Phosphorous Loading Analysis – City of Sammamish
  • Seasonal and Long-Term Effects Model of Lake Morphometry and Hydrological Alternatives for a Decommissioned Power Plant on Roslyn Lake – City of Portland
  • Water Quality Monitoring and Assessment of Tropic Conditions and Bull Trout Habitat in the Boundary Reservoir – Seattle City Light
  • Inventory of Aquatic and Terrestrial Plants, Vertebrate and Invertebrate Species in Capitol Lake – Washington Department of General Administration
  • Horseshoe Lake Phase II Restoration Project – King County
  • Freshwater Aquatic Plant Identification Manual – Washington Department of Ecology
  • Steel Lake Aquatic Plant Management Plan and Aquatic Plant Surveys – City of Federal Way