8/14/06

ELKHORNSLOUGH TIDAL WETLAND PROJECT

REQUEST FOR PROPOSALS

I. INTRODUCTION

The Elkhorn Slough estuary, containing California’s second largest tract of salt marsh, is currently facing unprecedented rates of estuarine habitat loss and degradation. Over the past 150 years, human actions have altered the tidal, freshwater, and sediment processes which are essential to support and sustain Elkhorn Slough’s estuarine habitats. This has led to substantial changes in the extent and distribution of tidal marsh, mudflat, creek, and channel habitats.

Accelerating bank and channel erosion in Elkhorn Slough is deepening and widening tidal creeks, causing salt marshes to collapse into the channel, and eroding soft sediments that provide important habitat for invertebrates from channel beds and mudflats. Habitat functions for estuarine fish, shorebirds, and salt marsh are rapidly deteriorating. Increased frequency of tidal flooding of marshes iscausing plants to “drown” in central areas of the marsh. Based on current knowledge, the accelerated rates of tidal erosion and marsh drowning are primarily due to the estuarine mouth modifications when a harbor was constructed at the mouth of Elkhorn Slough in 1947. Since that time, 50 percent of the salt marsh has beenlost due to marsh drowning and bank erosion and loss continues today at dramatic rates. The subsidence of marsh areas, the loss of riverine sediment inputs, and sea level rise may also contribute to marsh drowning.

The Elkhorn Slough estuarine system is not at equilibrium and it is predicted that the dramatic rates of estuarine habitat loss and degradation in Elkhorn Slough will continue in the near future if no restoration actions are taken.

Elkhorn Slough National Estuarine Research Reserve (Reserve) staff is leading a large collaborative effort, the Tidal Wetland Project (TWP), with the assistance of many partners to develop and implement strategies to conserve and restore estuarine habitats. Potential restoration alternatives developed as part of this RFP must meet the consensus TWP project goals that were developed during the planning phase, particularly Goals 1 and 3A (Appendix A). These groups considered a wide variety of restoration alternative concepts and ruled many of them out based on the anticipated results. The selected initial restoration alternatives include major alterations to the configuration of the Elkhorn Slough mouthto reduce the tidal prism and the associated accelerated erosion of channels, marshes, mudflats, and tidal creeks and inundation of marsh areas (Appendix B).

Additional information about the Elkhorn Slough Tidal Wetland Project can be found at

II. SCOPE OF SERVICES

The Reserve through the Elkhorn Slough Foundation is soliciting services to design and evaluate the hydrodynamic and ecosystem response to a suite of proposed restoration alternativesthat are intended to reduce tidal habitat loss and degradation, in addition to the no-action alternative. The work that constitutes the main focus of this RFP is to predict the hydrodynamic and geomorphic response of possible large-scale restoration alternatives in Elkhorn Slough. The overall timeframe to conduct and complete all phases in the scope of services is tentatively from October 1, 2006 through February 1, 2008.

The contractor will be expected to receive and integrate input from a wide range of participants, and assist the TWP’s Strategic Planning Team(SPT) and Science Panel(SP) (Appendix C) with devising restoration alternatives that will achieve a successful balance among project objectives. Technical work efforts will be guided by the Modeling Advisory Team and TWP Coordinator. The contractor selected for this project must ensure that project-related communications are effective, accurate, and timely.

Other investigators are evaluating related aspects of Elkhorn Slough as part of an Ecosystem-based Management project. These projects are described in Appendix C. Models and deliverables for this project must be developed in a collaborative manner with these investigators to provide output that can support their work, which emphasizes the following:

  • Species and ecological community distributions across the landscape
  • Nutrient transport
  • Socioeconomic impacts of restoration alternatives

At the end of this project, our goal is to have a detailed understanding of the viability andlikely effects of several restoration alternatives. This information will leadto a decision about how to pursue large-scale restoration of Elkhorn Slough. During this phase, conceptual designs of restoration options will be developed,and the critical tasks will be identified for progressing to the next phase of the project, which will involve feasibility analysis, detailed engineering and cost estimation, and regulatory compliance. All designs and modeling work needed to implement a project should be sufficiently documented and structured to be transferable to subsequent phases.

Existing data sources and investigations underway are listed in Appendix D. The contractor will be expected to work with the available data and to characterize the uncertainty in the analysis associated with incomplete data. Reportsshould, however, identify data gaps and requirements for subsequent phases of the project.

Key elements of this work include the tasks and deliverables described below. Inlet dynamics, hydrodynamic modeling, future geomorphic scenarios, and future habitat composition (Tasks C, D, E and F) will be analyzed for five restoration options at each of the following time periods:

  • Present
  • Present + 10 years
  • Present + 50 years

Additional hydrodynamic modeling runs will be required to characterize special conditions that are distinctive of this site(see Task D below).

Extensive modeling and the analysis of model results are required for this project. Model results (Task C) must be accompanied by an uncertainty analysis. For interpretations(Tasks D, E, and F)based on model output, the uncertainty in the results must be characterized through the use of statistics, sensitivity analysis, or other rigorous procedures.

Task A: conduct a Literature Review of similar restoration projects

Produce a brief report describing projects that successfully and unsuccessfully addressestuarine habitat loss and degradation related to increased tidal inundation and erosion. The review will bebased on scientific literature, restoration reports, and interviews with experts. The report is intended to assist in the identification and refinement of restoration options.

Task B: Develop conceptual designs of Large-scale restoration alternatives

Develop conceptual designs, including sketches and general descriptions of the work required, for large-scale restoration options 1-4 (Appendix B) identified by the Tidal Wetland Project’s SP and SPT (Appendix C). The main goal is to restore the natural processes in Elkhorn Slough (i.e. tidal prism, morphology, sediment inputs) to reduce the rate of salt marsh loss from tidal inundation and erosion, and channel, mudflat, and tidal creek degradation from tidal erosion(Appendix A).

Based on this work (including the Task A report) and their own expertise, the contractor may present additional restoration alternatives to the SP and SPT that would also meet project goals. For budgetary purposes, the contractor should assume that one additional restoration option will be identified, developed to the conceptual design phase, and evaluated in Tasks C through F below.

TASK C: PREDICT TIDAL INLET DYNAMICS

Develop a model of the tidal inlet, in concert with the hydrodynamic model, that characterizes the stability and geometry of the inlet for each restoration option. All proposed restoration options will affect the tidal prism of Elkhorn Slough, and in turn, the stability and geometry of the existing and proposed tidal inlets. Inlet stability and geometry are primary considerations in hydrodynamic modeling and in the design of restoration alternatives (Task G), particularly Option 2 (Appendix B), which aims to restore the historic location, dimensions, and sinuosity of the Elkhorn Slough mouth.

This analysis is necessary to predict the likelihood of estuarine mouth closure, changes to the sediment budget in the MossLandingHarbor, and as geometric input to the hydrodynamic model for each large-scale restoration option (including the no-action option). While the tidal inlet analysis and hydrodynamic model (below) must be consistent for each option and time period, it is not necessary to couple these models numerically.

TASK D: Model Hydrodynamic Processes

Developa hydrodynamic model of Elkhorn Slough and simulate each large-scale restoration alternative, including the no-action alternative, at each specified time period.

Construct a computational grid. Calibrate and validate the model for the present estuary conditions and document those steps, including a complete description of assumptions used. Existingdata available for calibration and validation is described in Appendix D. The collection of new field data is not an element of the proposed project.

Execute the model for each of the selected restoration options (Task B). The simulations must reflect the analysis of Tidal Inlet Dynamics (Task C). Future scenarios must account for predicted changes in the morphology of intertidal and subtidal areas (Tasks E and F) and projected changes in sea level. Develop maps of hydrodynamic characteristics throughout the Elkhorn Slough, including inundation frequency, tidal range, peak and mean velocity, volumetric exchange rate, and bottom shear stress under various tidal (i.e. spring, neap and average tide) and fluvial (i.e. base and extreme flow) conditions.

Provide supplemental model runs as needed to revise and refine restoration alternatives (Task B) and address specific design issues (Task F) or other questions such as various inlet geometries (see Task C) and episodic events. We expect a total of 20 model runs will be required to evaluate specific restoration options and address additional questions to characterize anticipated atypical conditions (e.g., floods, extreme tides, mouth closure).

Outputs from the hydrodynamic model will serve as inputs to other modeling and interpretation activities, including the analysis of geomorphic change (Task E). Model output must support analysis of erosionand deposition in the channel, tidal creeks, and intertidal mudflats and marshes. It should also include tidal range and inundation frequency to support the characterization of future habitat composition (Task F).

The uncertainty of model output must be characterized (see Scope of Services).

Hydrodynamic modeling should at least include the following:

  • Subtidal (channel, tidal creek) and intertidal (mudflat and marsh plain) hydrodynamics
  • Wetting and drying of intertidal regions
  • A model domain that extends into MontereyBay and includes the extent of the tidal habitats of the Elkhorn Slough system, including MossLandingHarbor, the Old Salinas River Channel, and all wetland areas that receive any tidal flow through water control structures
  • Watershed inputs of surface water
  • Water withdrawals at the Moss Landing power plant

Hydrodynamic modeling outputs should at least include the following for each restoration alternative:

  • Map of peak tidal velocities (including a map comparing peak velocities to the no-action alternative)
  • Tidal prism estimate
  • Map of bed shear stress and assessment of erodibility in the channel and along the banks
  • Map and summary of changes to tidal range and inundation frequency
  • Potential issues related to existing infrastructure (i.e. roads, railroad, jetty structures) such as stability and peak water surface elevations

In addition to the direct model outputs, the contractor should describe the assumptions made in calibrating, developing, and executing the model.

Task E: predict future morphological scenarios

Develop morphological (bathymetry/marsh elevation) scenarios for tidal habitats in Elkhorn Slough by interpreting output from the hydrodynamic model (Task D)and other sources of information (Task F, Appendix E) to predict erosion/deposition trends in subtidal and intertidal areas. Predict morphological trends for each large-scale restoration alternative (including the no-action alternative) for the time periods identified above. These predictions shouldbe based on observed erosion trends(Appendix E) in addition to hydrodynamic model output, and must include both subtidal and intertidal habitats. Watershed and littoral sources of sediment should be considered. Surface wave erosion should also be evaluated as an additional source of erosion. This analysis should present the aerial extent of various inundation frequency classes (correlated to habitat type in Task F), and indicate the trend (direction and rate) in area for each class.

The proposed methodology must be calibrated and validated by application to recent historic conditions. The uncertainty of predictions must be characterized (see Scope of Services). Future predictions must include an analysis and discussion of the relative importance of episodic events (i.e. floods and tectonic events) for different restoration options.

Morphological scenarios should include the following results:

  • Maps of erosion/deposition trends ofthe channel bed and banks
  • Maps of erosion/accretion trends in intertidal areas

And include discussion of:

  • The relative importance of the relationships between channel bed erosion, tidal creek extension, submerged head-cut migration, vegetated marsh loss from inundation and erosion,and bank failure with respect to habitat changes
  • The effectivenessof each restoration option inreducing these modes of habitat loss and degradation
  • How long-range predictions of restoration options compare with both periods in Elkhorn Slough’s history and with other estuaries in California to support the analysis of ecologic community structure (Appendix C)
  • Whether 100-year exogenous events (e.g., floods from the Pajaro or SalinasRiversor tsunamis) affect predictions of restoration options

TASK F:PREDICT FUTURETIDAL HABITAT COMPOSITION

Produce a brief review of tidal range and inundation frequency relating tomarsh elevation thresholds (porewater anoxia, etc.) associated with various estuarine communities in Elkhorn Slough.

Provide predictions of changes to estuarine habitats (percent change and acreage of habitat types) and produce a map showing habitat distribution and changes for each selected large-scale restoration option (including no-action) for each of the time periods specified. These predictions will be based on the morphological scenarios, hydrodynamic model outputs, and knowledge of processes that determine tidal habitats. Habitat types include tidal salt and brackish marshes, mudflats, tidal creeks, and channels.

An understanding of marsh ecosystem processes, such as marsh accretion and sea level rise, will be required to interpret the hydrodynamic and geomorphic analysis and make estimates of the extent and location of various habitat types.

The proposed methodology must be calibrated and validated by application to current and recent conditions. The uncertainty of results must be characterized (see Scope of Services).

Task G: create Designs of Large-scale restoration alternatives

Revise and further develop feasibility designs for selected large-scale restoration alternatives based on the modeling output (Tasks D and E), SP recommendations, and SPT decisions.

For two options identified by the SP and SPT, provide a 10% design level, including conceptual layout development and design drawings, preliminary cost estimates and design information such as approximate material quantity estimates, location of constructed features on a site plan, and a description of construction methods.

Define the critical tasks for progressing from the end of this project to final design and implementation. Estimate the budget for that work.

TABLE 1: GENERAL GUIDANCE FOREFFORT SPENT ON MAJOR TASKS
(TOTAL FUNDING AMOUNT FIXED AT $335,000)
Task / Deliverable Name / Percent Effort
A / Literature Review of Restoration Options / ~2.5%
B / Restoration Conceptual Designs (report including designs) / ~5%
C / Tidal Inlet Analysis (report) / ~5-10%
D / Hydrodynamic Model Results (report) / ~50-70%
E / Morphological Scenarios (map) / ~10-20%
F / Tidal Habitat Predictions (report) / ~5-10%
G / Restoration Engineering Designs / ~5-10%

III. REQUIREMENTS OF PROJECT DELIVERABLES

Several documents will be generated as part of the work proposed under this contract. Requirements for draft andfinal deliverables are described below. Table 1provides a list of the major deliverables identified for the proposed contract. Intermediate products will be defined in the negotiation of the final product.

The key components for each deliverable include the body of the report, executive summary, glossary of technical terms, table of contents, and a list of references (when applicable). Documents must be provided in both hard copy and electronic format (on CD), and all final documents must be provided in pdf format, so that they can be easily posted on the project website. All text should use 12-point font, 1.5 spacing, and 8.5x11 inch format. Draft deliverables that will be reviewed need to include line numbers. When possible, maps will be compatible with a GIS database.

Coordination activities required of the contractor may include attending working group meetings, giving presentations, preparing written material, and ensuring that the various groups are kept up to date on the progress of technical activities. Contractors will provide two presentations of their draft and final project results to the Tidal Wetland Project teams and attend working group meetings with the Modeling Advisory Team at least quarterly. Presentations will be posted on the project web site.

Effective quality control and assurance procedures are essential for ensuring the technical integrity of the deliverables prepared for the project. Draft technical products will be reviewed by the Modeling Advisory Team. As needed, documents may also be reviewed by specific members of the TWP teams and/or independent technical experts. Contractors will be responsible for compiling and incorporating review comments or documenting reasons why comments were not incorporated.

IV. INFORMATION TO BE INCLUDED IN SUBMITTAL

A. Cover Page

B. Intended Approach demonstrates the process that will be used to complete the Task(s) proposed.

Contractors are required to form their own teams to accomplish all of the tasks outlined in this request for proposals. Feel free to contact us if you need any assistance in assembling these teams.

Describehow you intend to accomplish each of the specific tasks in this proposal. Include a timeline demonstrating your proposed start and end dates for the products in each task. Explain how you will integrate intermediate and final information generated from certain tasks to others.