Procedural Guidance Document : Monitoring : Shoreline Protection and Beach Nourishment Projects

A Note on the Use of This Document

Use of this document and other procedural guidance addressing responses to beach erosion will provide a more consistent approach than has been utilized by Commission staff in the past to analyze the cumulative impacts of shoreline protective devices on beach sand supply and, therefore, on public access and recreation. The information contained in this document will identify mitigation measures which can be used to address long-term impacts to public beaches in a more comprehensive manner than under current practice. Such a change will respond to the findings of the Commission’s Regional Cumulative Assessment Project (ReCAP December 1994) which documented that large sections of the pilot shoreline were being armored through emergency and regular permits for individual site protection. The ReCAP findings and other staff work contributed to a growing body of evidence that armoring a bluff, in addition to encroaching onto the beach and preventing its further landward migration, will reduce the amount of sand and gravel entering the littoral cell, and will cause the narrowing of an eroding beach over time and reduction in the area of sand available for recreational use.

This procedural guidance document will serve as a resource to assist Commission staff in preparing their analyses and recommendations upon which the Commission bases its decisions; thus, enhancing the Commission’s ability to protect the State’s beaches and adjacent coastal resources. It is important, however, to accurately characterize this document and explicitly delineate its appropriate use.

Consistent with the authority delegated to the Executive Director to direct the work of staff, and consistent with the Commission’s duty to examine projects, amendments, and other items for Commission action on a case-by-case basis, this document will provide staff with relevant information for drafting proposed findings and assessing compliance with permit conditions. However, this document has not been adopted by the Coastal Commission. Thus, although the sources of information (e.g., scientific methodology or previous Commission actions) contained in this document can be referenced when developing a staff report, this procedural guidance document itself will not be cited, quoted, or relied upon as the basis for recommendations or findings contained in any staff report.

VERTICAL SEAWALL
As-Built Changes Made to Approved Project
Condition of the vertical wall
Beach Conditions in front of and/or Down coast of the Vertical Wall
Bluff Conditions Landward of the Vertical Wall
Scour in front of the wall and End Effects adjacent to the wall

REVETMENT
As-Built Changes Made to Approved Project
Condition of the revetment
Beach Conditions in front of and/or Down Coast of the Revetment
Bluff Conditions Landward of the Revetment
Scour in front of the revetment and End Effects adjacent to the revetment

CAVE FILLING
As-Built Changes Made to Approved Project
Condition of the Cave Filling
Conditions of Drainage through and Adjacent to cave Fill
Bluff Conditions Landward of the cave Fill
Scour in front of the Cave Facing
Beach Conditions in front of and/or Down Coast of the Cave Fill

GROIN OR JETTY
As-Built Changes Made to Approved Project
Condition of the Groin or Jetty
Beach Conditions Up- and Down-Coast of Groin or Jetty

BEACH NOURISHMENT
As-Built Changes Made to Approved Project
Beach Conditions at Receiver Beach and Down Coast Areas
Performance Related Conditions

ATTACHMENT A: MAJOR COMPONENTS OF A MONITORING PROGRAM
1.0 Objectives of Monitoring Program (Why)
2.0 Features to be Monitored (What and Where)
3.0 Monitoring Methods
4.0 Monitoring Schedule (When)
5.0 Reports on Monitoring Efforts
6.0 Maintenance Activities
7.0 Performance Criteria

SHORELINE PROTECTION AND BEACH NOURISHMENT PROJECTS

Monitoring[1] has been defined by the National Research Council, as "the systematic collection of physical, environmental, or economic data or a combination of these data on a beach nourishment project in order to make decisions regarding project operation or to evaluate project performance."[2]While this definition addresses beach nourishment, it is equally applicable to other types of shoreline protection projects (seawalls, revetments, cave filling, groins, etc.). In almost all situations, monitoring is a way to answer questions about project effectiveness and to identify project strengths and weaknesses.

Monitoring is one way to answer questions about a project — How will it perform? What will happen to downcoast areas? Will surf change? Monitoring often can be tied to some response action or follow up maintenance; but, it is not by itself a way to improve the performance of a project or to mitigate for impacts. Monitoring cannot substitute for adequate information about the project design, the project location, or the benefits or effects from similar projects.

Objectives of a monitoring program will vary from project to project, but could include, among other objectives, to:

For individual projects, the monitoring objectives should be defined as specifically as possible and should address the individual circumstances of the proposed project.

There are several circumstances where monitoring may be very appropriate as part of a permit approval for shoreline protection and beach nourishment projects. First, Section 21081.6 of the California Environmental Quality Act provides the authority to adopt a monitoring program to insure compliance with project changes or conditions during project implementation. Also, if the project is proposed as a pilot study or as a first phase of a multi-phase effort, early monitoring may provide information which will be essential for thorough evaluation of later projects or later phases of the same project. The details of such monitoring would depend on the pilot study or the multi-phase project and cannot be detailed in a general document such as this. Normally a pilot study or multi-phase project will contain some goals, purposes, intermediate evaluation steps, etc. from which the monitoring program could be developed.

Some projects are undertaken to improve a coastal situation, or to correct some identified problem, for example, to provide better coastal access, to improve recreation, or to reduce the downcoast erosion which has been attributed to a structure. Such projects often will be recommended for approval based on an expectation that the long-term anticipated benefits will be greater than the temporary adverse effects on access, recreation, habitat, sand supply, noise etc. For projects of this type, monitoring could be used to determine if the project provided the anticipated result.

When beach nourishment is used for protection of back beach or upland structures, monitoring may be critical to scheduling necessary maintenance and renourishment. Monitoring could be used to determine the frequency of maintenance and renourishment, to insure that a sufficient beach is available so that individual structures will not be in danger from erosion and thus require a more intrusive form of shoreline protection, and to minimize impacts to public access and recreation from unnecessarily frequent maintenance and renourishment. Available monitoring data could enable the Commission, or staff with proper direction from the Commission, to work closely with the applicant to insure timely maintenance and renourishment without repeated permits or permit amendments.

Finally, to provide the Commission with the best possible understanding of the proposed project and its consistency with the California Coastal Act, analysts must have access to the best available information on the proposed project and project location and must use their best judgment in evaluating the levels or significance of impacts which may result from a proposed action. While the impacts will vary for different projects, there can be some common or frequently encountered situations for which monitoring may be helpful. For example, most shoreline protection efforts, both hard structures and beach nourishment, will have some impact on public access and recreation and many may effect local shoreline sand supplies. Whenever there is some uncertainty about the level or significance of impact from a proposed project, information gained from monitoring the real world effects can improve the information on future projects and improve the Commission’s decisionmaking capability. Without follow-up information, available often through monitoring, it is difficult to improve the input analysis which is used in the Commission’s decisionmaking process or to determine whether the level of significance to each impact which has been ascribed historically to an impact should be increased or decreased.

One of the biggest challenges for an analyst who is designing a monitoring program, or is helping an applicant design a monitoring program, is to ask detailed, focused questions. Detailed, focused questions will direct the monitoring program and improve the chances that the program will eventually provide useful information. For example, if there is concern that a new groin may cause extensive downcoast erosion, rather than ask how the downcoast beach will change, the analyst may ask what will be the long and short term changes to beach width at various specified locations. A complete monitoring effort identifies all the standard questions used by a newspaper reporter — who, what, why, when, where, how, and, possibly, so what.

A monitoring program should address these "reporter questions". The level of detail in the program will vary for different projects. In some situations, the complete monitoring program can be described in a brief letter. For example, if the monitoring program is an effort to undertake annual visual inspections of sea cave fills and to notify Commission staff whenever reinforcing bar is exposed, the full program could be outlined in several paragraphs. In most situations, a more detailed and lengthy program will be needed. In such cases, the analyst may ask the applicant to prepare the program details and submit a separate monitoring document, using general direction provided by the analyst. Attachment A is a general outline for a monitoring program which may be used as a guide for preparation or as a general checklist to determine if the program seems complete.

Most shoreline protection efforts (structures or nourishment) need occasional maintenance for the protection effort to continue to perform effectively. In many cases, maintenance occurs when someone notices that there is a possible problem, following a major storm event which may have damaged the shoreline protection, or when there is extra sand or rock from another project and maintenance can be done conveniently. Such maintenance can be rather hit-or-miss, and can lead to extensive deterioration of the protective measure before any corrective action is taken. One drawback to such a maintenance approach is that the deteriorating structure may have greater impacts on public access and recreation than would a well maintained structure. Also, if maintenance needs are ignored for too long, it may be necessary to totally replace the deteriorating structure with a larger structure that could have greater impacts on recreation and access than the initial structure.

An alternative to random maintenance is to initiate a monitoring program which provides triggers or conditions which would lead to some form of maintenance. In these situations, the "so what" of monitoring would usually be anticipated maintenance. A trigger for maintenance is a difficult concept to understand and it may best be described through general examples. For a revetment, a trigger might be movement of rip rap from the revetment such that there is rock located seaward of the original footprint of the structure. If structural height is a concern, a different trigger might be the settling or subsidence of a structure below a certain point or elevation. For an on-going beach nourishment project, a trigger might be the reduction of dry beach to less than some minimum width necessary either to provide access during high tide and/or to provide storm protection to upland structures. Project specific maintenance triggers would depend on the proposed project and its location.

If the various triggers and maintenance steps can be identified during review of an application for shoreline protection, the analyst may be able to include anticipated maintenance within the initial coastal development permit. The analyst should keep open the opportunity to review any extraordinary maintenance. Also, the inclusion of maintenance in the initial coastal development permit (either as part of the project description or as a permit condition) should not allow situations where routine maintenance is deferred for so long that the maintenance essentially rebuilds the project without benefit of a new or amended coastal development permit.

Just as every coastal development permit application must be examined for the characteristics of the specific project, a monitoring project must address the specific concerns about the project and the area in which it will be constructed. Table 1 lists some of the more typical shoreline projects and some of the general features or characteristics which can be monitored. This Table is not intended to be comprehensive; it covers some of the more typical features which are monitored, such as beach width and upper bluff retreat, and it covers some features which are less well understood, such as scour and end effects.

One obvious element of Table 1 is the need for some baseline or pre-project information whenever the monitoring program attempts to identify or measure changes which can be attributed to the completed project. Without information on local conditions prior to the project, it is usually impossible to separate project related changes from natural variability. Baseline information about a site can often be developed from the site characterization and project plans. If there is an on-going local or regional shoreline monitoring program, many of the baseline or pre-project conditions may develop from this on-going program. If baseline or pre-project conditions cannot be documented easily, the analyst must determine whether there would be value in monitoring without this information. The analysts must use their best judgment in making these determinations and must considering the specific circumstances of the site and the project.

The following pages cover, in general, many of the "reporter questions" which can be asked for vertical seawalls, revetments, cave filling, groins or jetties, and various types of beach nourishment. This material is provided to prompt ideas and assure the analyst that they have not overlooked the larger or more obvious concerns which could be addressed through monitoring. It is very unlikely that any one project would require all the identified monitoring elements and many projects could be approved without any monitoring. Such decisions must be based on the individual project, and no list can replace a careful, project specific analysis. In all cases, the questions may vary to fit the specific project. Also, the analyst or applicant may have ideas for different techniques which could provide the necessary information.

The level of monitoring should reflect, to an extent, the expected effects and the uncertainty in the significance of these effects. If the effects will be slight, there may be no justification for monitoring, regardless of the uncertainty about whether an effect will occur. Likewise, if there is high certainty about an effect, monitoring may not provide any gain and it may be preferable to consider mitigation or project denial.

Monitoring will vary from one project to the next; however, it is necessary to have some level of consistency between different area offices on the uses and requirements of monitoring so that similar projects will be treated consistently throughout the state. Eventually, monitoring should be part of the permit tracking effort which is being installed in each office. For the present, whenever monitoring is part of a permit for shoreline protection or beach nourishment, either as part of the project description or as a permit condition, the analyst should fill out the attached tracking form, keep a copy in the District office, and send a copy to the Technical Services Unit. If there is time, the analyst should contact the Technical Services Unit prior to requiring monitoring to determine if there are similar projects in other areas which are being monitored. Each year the Technical Services Unit can prepare an internal report on the monitoring of shoreline protection and beach nourishment, based on the information provided in the tracking forms and follow-up with analysts.

TYPE OF PROJECT

PRE-CONSTRUCTION PROJECT AND SHORELINE CHARACTERISTICS

POST-CONSTRUCTION PROJECT AND SHORELINE CHARACTERISTIC

Vertical Seawall

Beach and upland profile at location of proposed wall, showing upper bluff or back beach and beach elevations; extending to mean lower low water, wading depth or other acceptable seaward point.

Beach width in front of wall.

Beach width down coast of wall.

Locations of water seeps on the bluff face.

As-built changes made to approved project.

Condition of wall and need for maintenance.

Beach width in front of wall.

Beach width down coast of wall.

Retreat of upper bluff.

Scour in front of wall.

End effects/ end scour adjacent to wall.

Revetment

Beach and upland profile at location of proposed revetment, showing upper bluff or back beach and beach elevations; extending to mean lower low water, wading depth or other acceptable seaward point.

Beach width in front of revetment.

Beach width down coast of revetment.

As-built changes made to approved project.

Condition of revetment and need for maintenance.

Beach width in front of revetment.

Beach width down coast of revetment.

Seaward edge of revetment and revetment slope.

Scour in front of revetment.

End effects/ end scour adjacent to revetment.

Cave Filling

Locations of water seeps exposed on bluff face.

Beach width in front of cave fill.

Beach width down coast of cave fill.

As-built changes made to approved project.

Condition of cave fill and need for maintenance.

Adequacy of drainage through cave fill.

Changes to drainage along areas adjacent to cave fill

Scour in front of cave facing.

Beach width in front of and adjacent to cave filling.

Groin or Jetty

Up and down coast beach width.

Up and down coast beach slope.

Planned pre-fill amounts and design.

(Also add all information for appropriate nourishment.)

As-built changes made to approved project.

Condition of beach fill and groin or jetty, and need for maintenance.

Up and down coast beach width.

Up and down coast beach slope.

(Also add all information from appropriate nourishment.)

Beach Nourishment

Source: Offshore or submarine (dredged)

Receiver: Nearshore

Grain size, color and physical properties of source and receiver material.

Chemical contaminants of source and receiver material.

Design of offshore berm.

Width and slope of beaches near offshore berm.

As-built changes made to approved project.

Final amount of nourishment.

Width and slope of beaches near offshore berm.

Beach Nourishment

Source: Offshore or submarine (dredged)

Receiver: Onshore

Grain size color and physical properties of source and receiver material.

Chemical contaminants of source and receiver material.

Design of onshore berm.

Width and slope of receiver beach.

Width and slope of downcoast beach.

As-built changes made to approved project.

Final amount of nourishment.

Width and slope of receiver beach.

Width and slope of downcoast beach.

Beach Nourishment

Source: Onshore/ Inland (excavated material)

Receiver: Nearshore

Grain size, color and physical properties of source and receiver material.

Chemical contaminants of source and receiver material.

Design of offshore berm.

Width and slope of beaches near offshore berm.

As-built changes made to approved project.

Final amount of nourishment.

Width and slope of beaches near offshore berm.

Beach Nourishment

Source: Onshore/ Inland (excavated material)

Receiver: Onshore

Grain size, color and physical properties of source and receiver material.

Chemical contaminants of source and receiver material.

Design of onshore berm.

Width and slope of receiver beach.

Width and slope of downcoast beach.

As-built changes made to approved project.

Final amount of nourishment.

Width and slope of receiver beach.

Width and slope of downcoast beach.

VERTICAL SEAWALL

Some typical questions about vertical seawalls which could be addressed through monitoring are provided below.

(Verification that the wall construction followed the approved design and identification of as-built changes)

Usually, the contractor can make a determination about whether the vertical wall was built according to the design which was approved in the permit. The applicant can be required to provide a copy of the approved project description with the bid documents, and to obtain from the contractor a statement which either verifies that the final project conforms with the approved project or identifies all ways in which the final project differs from that which was approved. Project changes could be noted on a copy of the project plans or through new as-built plans. If the analyst wants to check this information independently, the exposed dimensions can be measured with a tape measure and color and texture can be determined through visual examination.

Monitoring of the wall conditions can be accomplished rather easily by routine visual inspection, comparing the wall to its as-built condition. In many situations the work can be done by the property owner; however, if there is additional monitoring which requires a licensed engineer, it may be less confusing if all monitoring is performed and reported together. Visual monitoring for rust staining, exposed reinforcing bar and spalling can be documented, if necessary, with clear photographs of the wall. Wall tilt can be determined with a hand held level or a plume line. If either process shows that the wall has moved, a licensed engineer or surveyor should be brought in to measure the extent of tilt and determine what, if any, additional action is necessary. Since wall tilt can be a sign of potential failure, a licensed engineer should take part in the discussions on corrective measures. Releveling a vertical seawall should not be considered a normal or routine element of seawall "maintenance".

Monitoring beach conditions after a seawall is installed normally requires some baseline information of the beach conditions prior to installation of the wall. Beach width should be measured prior to the installation of the vertical wall at various identifiable locations, spaced regularly along the beach. If the concern is for dry beach area, the measurements can be made using a tape measure, measuring from the base of the bluff or from the base of the seawall to a seaward limit such as the wetted bound. The same locations should be measured once or twice a year, for a given period of time (for example, five or ten years, or possibly for as long as the wall is standing and there is any measurable beach seaward of the wall). It is important that the year to year measurements be taken in the same way, at the same shoreline locations and during the same time period, such as always during the same season, month, or two week period.

If the vertical wall does not extend the entire height of the bluff, it may be useful to monitor the long-term change in upper bluff conditions after installation of a vertical wall. This will require information on the baseline or pre-project bluff condition. A profile of the bluff face, bluff edge and top of bluff should be prepared prior to or immediately following the installation of the vertical wall, measured at one or more locations along the bluff. If the bluff is relatively uniform, retreat measurement may be made from one "typical" location possibly somewhere near the center of the bluff or between the two property lines. If the bluff is very irregular, it may be necessary to select measurement points every 10 or 20 feet to insure that future bluff changes will be identified during the monitoring. Changes in bluff profile can be obtained through repeated surveys of the profile or from periodic photographs shot from the same spot and taken of the same location. Changes in the landward retreat of the bluff can be measured from fixed locations. such as the corners of a building, a man hole cover, a street light, etc. to the top of the bluff using a tape measure. The critical part of this measurement is insuring that the measurements be undertaken by someone familiar with the Coastal Act definition of top of bluff (Public Resources Code Section 13577) and that the measurer can identify the top of bluff whenever the measurements at required. If the profiles are measured by a licensed surveyor, the profiles should be tied into an established survey marker or benchmark, and all measurements should be referenced to this benchmark.

Monitoring scour in front of or on the beach adjacent to a vertical wall requires information on the elevation of the beach in front of or adjacent to the wall both before and after a scour event. One element of a program to monitor scour would be the ability to predict when a scour event will occur so that the pre-scour beach elevation can be measured. Scour depth could then be measured as the lowering of the beach elevation in front of or on the beach adjacent to the wall, measured either during or immediately after the scour event. The depth of scour, multiplied by the length and seaward width of the scour depression would approximate scour volume. Repeated and frequent measurements of beach depth after the occurrence of scour could be used to determine when the beach elevation returns to the pre-scour elevation and to indicate the duration that scour would be noticeable. If it is not possible or reasonable to measure beach elevations prior to a scour event, the pre-event beach elevation can be approximated from:

Any irreversible accelerated bluff retreat adjacent to a vertical seawall can be noted from visual inspections of the bluff adjacent to the vertical wall and can be documented by photographs. Such retreat will normally look like a small depression, discontinuity or hole along the bluff face. This retreat may not occur; if it does, the first concern is simply to document its occurrence, through photographs, text, etc. The extent of retreat can be surveyed or an indication of extent can be developed from measuring retreat with a tape measure, where the important dimensions would be the depth of retreat compared with a fixed feature, such as the vertical wall, the height of the retreat and the distance along the bluff where this retreat is evident.

Revetment

Some typical questions about revetments which could be addressed through monitoring are provided below.

(Verification that the wall construction followed the approved design and identification of as-built changes)

Usually, the contractor can make a determination about whether the revetment was built according to the design which was approved in the permit. The applicant can be required to provide a copy of the approved project description with the bid documents, and to obtain from the contractor a statement which either verifies that the final project conforms with the approved project or identifies all ways in which the final project differs from that which was approved. Project changes could be noted on a copy of the project plans or through new as-built plans. If the analyst wants to check this information independently, the exposed dimensions can be measured with a tape measure and sizes of rock can be either measured or estimated through visual examination; the type of material can be determined through visual inspection.

Monitoring of the revetment conditions may be accomplished rather easily by routine visual inspection, comparing the revetment to its as-built condition. In many situations the work can be done by the property owner; however, if there is additional monitoring which requires a licensed engineer, it may be less confusing if all monitoring is performed and reported together. Visual monitoring for exposed geotextile fabric or shifted revetment rock can be documented, if necessary, with clear photographs of the structure. Wall elevation and seaward rotation can be identified through movement of the top of the revetment. Movement of the top of the revetment determined through surveys or with a tape measure if there is a fixed point to which the elevation and seaward limit of the revetment could be referenced. If the revetment has moved, a licensed engineer or surveyor should be brought in to measure the elevation loss and determine what, if any, additional action is necessary. In many coastal areas, wave action will cause a shifting of revetment material fairly regularly. A revetment can be used for many years to effectively protect upland property if there is regular inspection and maintenance (such as repositioning rock into the revetment if it has shifted seaward, or adding small amounts of rocks if the revetment is settling slowly).

Monitoring beach conditions after a revetment is installed normally requires some information on the beach conditions prior to installation of the revetment. Beach width should be measured prior to the installation of the revetment, measured at various identifiable locations, spaced regularly along the beach. If the concern is for dry beach area, the measurements can be made using a tape measure, measuring from the base of the bluff, seaward extent of vegetation, or base of the revetment to a seaward limit such as the wetted bound. (If the base of the revetment is used to measure the width of dry beach, care must be taken to first check that the revetment footprint has not shifted seaward.) The same locations should be measured once or twice a year, for a given period of time (for example, five or ten years, or possibly for as long as the revetment is standing and there is any measurable beach seaward of the revetment). It is important that the year to year measurements be taken in the same way, at the same shoreline locations and during the same time period, such as always during the same season, month, or two week period.

Monitoring the long-term change in upper bluff conditions after installation of a revetment will require information on the pre-project or baseline bluff. A profile of the bluff face, bluff edge and top of bluff should be prepared prior to or immediately following the installation of the revetment, measured at one or more locations along the bluff. If the bluff is relatively uniform, retreat measurement may be made from one "typical" location possibly somewhere near the center of the bluff or between the two property lines. If the bluff is very irregular, it may be necessary to select measurement points every 10 or 20 feet to insure that future bluff changes will be identified during the monitoring. Changes in bluff profile can be obtained through repeated surveys of the profile or from periodic photographs shot from the same spot and taken of the same location. Changes in the landward retreat of the bluff could be measured from fixed locations. such as the corners of a building, a man hole cover, a street light, etc. to the top of the bluff using a tape measure. The critical part of this effort is insuring that the measurements be undertaken by someone familiar with the Coastal Act definition of top of bluff (Public Resources Code Section 13577) and that the measurer can identify the top of bluff whenever the measurements at required. If the profiles are measured by a licensed surveyor, the profiles should be tied into an established survey marker or benchmark, and all measurements should be referenced to this benchmark.

Scour is more likely to occur in front of or adjacent to a vertical surface rather than the non-uniform face of a revetment. If scour could be a significant concern, or if there is evidence from existing revetment in the area that scour can occur, it may be appropriate to monitor for scour.

Monitoring scour in front of or on the beach adjacent to a revetment requires information on the elevation of the beach in front of or adjacent to the revetment both before and after a scour event. One element of a program to monitor scour would be the ability to predict when a scour event will occur so that the pre-scour beach elevation can be measured. Scour depth could then be measured as the lowering of the beach elevation, measured either during or immediately after the scour event. The depth of scour, multiplied by the length and seaward width of the scour depression would approximate scour volume. Repeated and frequent measurements of beach depth after the occurrence of scour could be used to determine when the beach elevation returned to the pre-scour elevation and indicate the duration that scour would be noticeable. If it is not possible or reasonable to measure beach elevations prior to a scour event, the pre-event beach elevation can be approximated from:

Any irreversible accelerated bluff retreat adjacent to a revetment can be noted from visual inspections of the bluff adjacent to the revetment and can be documented by photographs. Such retreat will normally look like a small depression, discontinuity or hole along the bluff face. This retreat may not occur; if it does, the first concern is simply to document its occurrence, through photographs, text, etc. The extent of retreat can be surveyed or an indication of extent can be developed from measuring retreat with a tape measure, where the important dimensions would be the depth of retreat compared with a fixed feature, possibly the revetment if it has not shifted significantly, the height of the retreat and the distance along the bluff where this retreat is evident.

Cave Filling

Some typical questions about cave filling projects which could be addressed through monitoring are provided below.

(Verification that the wall construction followed the approved design and identification of as-built changes)

Usually, the contractor can make a determination about whether the cave filling was built according to the design which was approved in the permit. The applicant can be required to provide a copy of the approved project description with the bid documents, and to obtain from the contractor a statement which either verifies that the final project conforms with the approved project or identifies all ways in which the final project differs from that which was approved. Project changes could be noted on a copy of the project plans or through new as-built plans. If the analyst wants to check this information independently, the exposed dimensions can be measured with a tape measure and dimensions of the fronting wall can be either measured or estimated through visual examination; the texture and color can be determined through visual inspection.

Monitoring of the cave filling conditions may be accomplished rather easily by routine visual inspection, comparing the cave filling to its as-built condition. In many situations the work can be done by the property owner; however, if there is additional monitoring which requires a licensed engineer, it may be less confusing if all monitoring is performed and reported together. Visual monitoring for exposed reinforcing bar, rust staining or concrete spalling can be documented, if necessary, with clear photographs of the structure.

Most of the drainage conditions for a cave fill can be monitored by visual inspection, provided there has been an effort to locate and map all the drainage locations prior to or immediately after the cave filling. In many situations the work can be done by the property owner; however, if there is additional monitoring which requires a licensed engineer, it may be less confusing if all monitoring is performed and reported together. Normally water will establish a pathway through the bluff and maintain the same general path until something happens to block that path or make an alternate pathway easier to use. The most obvious identification of water is to see it actually flowing along the bluff face. Other indications of water are concentrations of vegetation or algae, mineral staining on the bluff, or if the water is through a concrete structure, there may be rust stains from oxidized reinforcing.

Monitoring the long-term change in upper bluff conditions after installation of a cave fill will require information on the pre-project or baseline bluff. A profile of the bluff face, bluff edge and top of bluff should be prepared prior to or immediately following the installation of the cave fill, measured at a typical location along the bluff. If the bluff is relatively uniform, retreat measurement may be made from one "typical" location possibly somewhere near the center of the bluff or above the cave fill. If the bluff is very irregular, it may be necessary to select measurement points every 10 or 20 feet to insure that future bluff changes will be identified during the monitoring. Changes in bluff profile can be obtained through repeated surveys of the profile or from periodic photographs shot from the same spot and taken of the same location. Changes in the landward retreat of the bluff could be measured from fixed locations. such as the corners of a building, a man hole cover, a street light, etc. to the top of the bluff using a tape measure. The critical part of this effort is insuring that the measurements be undertaken by someone familiar with the Coastal Act definition of top of bluff (Public Resources Code Section 13577) and that the measurer can identify the top of bluff whenever the measurements at required. If the profiles are measured by a licensed surveyor, the profiles should be tied into an established survey marker or benchmark, and all measurements should be referenced to this benchmark.

Scour is more likely to occur in front of or adjacent to a flat vertical surface rather than a non-uniform face. The more textured and varied the front of the cave fill, the less likely it is that scour would be significant in front of the cave fill. If scour could be a significant concern, or if there is evidence from existing cave fills in the area that scour can occur, it may be appropriate to monitor for scour.

Monitoring scour in front of or on the beach adjacent to a cave fill requires information on the elevation of the beach in front of or adjacent to the cave fill both before and after a scour event. One element of a program to monitor scour would be the ability to predict when a scour event will occur so that the pre-scour beach elevation can be measured. Scour depth could then be measured as the lowering of the beach elevation, measured either during or immediately after the scour event. The depth of scour, multiplied by the length and seaward width of the scour depression would approximate scour volume. Repeated and frequent measurements of beach depth after the occurrence of scour could be used to determine when the beach elevation returned to the pre-scour elevation and indicate the duration that scour would be noticeable. If it is not possible or reasonable to measure beach elevations prior to a scour event, the pre-event beach elevation can be approximated from:

Any irreversible accelerated bluff retreat adjacent to a cave fill can be noted from visual inspections of the bluff adjacent to the cave fill and can be documented by photographs. Such retreat will normally look like a small depression, discontinuity or hole along the bluff face. This retreat may not occur; if it does, the first concern is simply to document its occurrence, through photographs, text, etc. The extent of retreat can be surveyed or an indication of extent can be developed from measuring retreat with a tape measure, where the important dimensions would be the depth of retreat compared with a fixed feature, possibly the revetment if it has not shifted significantly, the height of the retreat and the distance along the bluff where this retreat is evident.

Monitoring beach conditions after a cave fill is installed normally requires some baseline information of the beach conditions prior to installation of the fill. Beach width should be measured prior to the installation of the cave fill, measured at various identifiable locations, spaced regularly along the beach. If the concern is for dry beach area, the measurements can be made using a tape measure, measuring from the base of the bluff, from the seaward extent of vegetation or from the base of the cave fill to a seaward limit such as the wetted bound. The same locations should be measured once or twice a year, for a given period of time (for example, five or ten years, or possibly for as long as the cave fill is standing and there is any measurable beach seaward of the fill). It is important that the year to year measurements be taken in the same way, at the same shoreline locations and during the same time period, such as always during the same season, month, or two week period.

Groin or Jetty

Some typical questions about groins or jetties which could be addressed through monitoring are provided below. Groins and jetties normally interrupt long shore sand transport, causing an accretion of sand up-coast of the structure and some erosion of sand down coast of the structure. As a result, groins and jetties often are "pre-filled" to create the up coast accretion of sand during construction and to supply enough extra sand downcoast of the groin or jetty to prevent erosion of the pre-existing beach. If a groin or jetty has included a significant amount of fill as part of the project, it could be appropriate to monitor the fill as well as the structure. The following questions address the structure. Please refer to the discussion on beach nourishment for monitoring questions addressing the fill portion of the project.

(Verification that the wall construction followed the approved design and identification of as-built changes)

Usually, the contractor can make a determination about whether the groin or jetty was built according to the design which was approved in the permit. The applicant can be required to provide a copy of the approved project description with the bid documents, and to obtain from the contractor a statement which either verifies that the final project conforms with the approved project or identifies all ways in which the final project differs from that which was approved. Project changes could be noted on a copy of the project plans or through new as-built plans. If the analyst wants to check this information independently, the exposed dimensions can be measured with a tape measure and sizes of rock can be either measures or estimated through visual examination; the type of material can be determined through visual inspection. Great care should be taken if the analyst tries to measure the length of the groin or jetty as wave action could make access to the end of the groin or jetty slippery and unstable.

The ease or difficulty of monitoring conditions of a groin or jetty will depend upon whether there is a safe vantage point to observe the groin or jetty conditions. Much of the monitoring may be accomplished by routine visual inspection if a safe vantage point is available. If there is not a safe vantage point for observing the groin or jetty, it may be necessary to do all monitoring either from a boat or from the water. Such monitoring should only be undertaken by trained individuals who recognize the potential dangers of working in a high energy wave environment.

The existing conditions can then be compared with the as-built conditions. In most situations the work can be done by the property manager, individual, homeowners association or company with long-term responsibility for the structure, or a consultant. Visual monitoring for exposed geotextile fabric, clogging with sand or shifted rock can be documented, if necessary, with clear photographs of the structure. Seaward rotation of rocks at the end of the structure can be identified through loss of material at the top and end of the groin or jetty. Movement of the top of the revetment determined through surveys or with a tape measure if there is a fixed point to which the elevation and seaward limit of the revetment could be referenced. If efforts show that the groin or jetty has lost material, a licensed engineer or surveyor should be brought in to measure the elevation loss and determine what, if any, additional action is necessary.

(Both concerns assume that there was only minimal fill associated with the groin or jetty.
If there was significant fill, please refer to section on beach nourishment.)

Monitoring beach conditions after a groin or jetty is installed normally requires some baseline information of the beach conditions prior to installation of the structure. Beach width and slope should be measured prior to the installation of the structure, measured at various identifiable locations, spaced regularly along the beach. The pre-project measurements should be similar to, or more extensive than the post-project measurements which will be undertaken. For example, if the post-project monitoring is concerned only with available dry beach width, the pre-project measurements could use either dry beach width measurements or full profiles to closure depth. However, if the post-project is concerned with sand transport throughout the littoral cell and will require full profiles to closure, it would not be useful to have only dry beach width for the pre-project measurements.

If the concern in beach width is for dry beach area, the measurements can be made using a tape measure, measuring from the base of a bluff or seawall, from the seaward extent of vegetation, or from another easily identified location on the shoreline, to a seaward limit such as the wetted bound. Locations should be selected for both up and down coast measurements of beach width. The same locations should be measured once or twice a year, for a given period of time (for example, five or ten years, or possibly for as long as the groin or jetty is standing and there is any measurable beach adjacent to the groin or jetty). It is important that the year to year measurements be taken in the same way, at the same shoreline locations and during the same time period, such as always during the same season, month, or two week period.

If there is concern that the groin or jetty will interrupt long-shore transport, the beach measurements for both up and down coast beach locations should provide profiles from the back beach to a near-shore point, such as depth of closure. Such measurements must be undertaken by licensed surveyors with expertise in both land and bathymetric surveys. Likewise, if the concerns is for changes in beach slope, the measurements should be made by professional surveyors. The critical elements that should be described in the monitoring plan would be the locations of the surveys, the timing of the surveys and their frequency.

Beach Nourishment

Beach nourishment programs are the shoreline protection efforts which are most regularly monitored, for a number of reasons. First, if used for shoreline protection, beach nourishment may be monitored to develop a replenishment schedule. Second, beach nourishment is often an expensive effort which is undertaken for a large beach area or entire beach community, and the funding entities want information on the performance of the project to use in later decisionmaking efforts. Third, because of the large areas over which sand may be placed, there may be some sensitive resource areas which should be carefully watched to trigger protective measures or to improve future placement efforts. Finally, as beach sand is viewed increasingly as a valuable resource, decisionmakers will want information about the performance of each project to make decisions about future allocations of available beach material.

Because beach nourishment has been regularly monitored, and there are a number of articles, reports and guidelines for various aspects of beach nourishment. The Corps of Engineers has published technical notes on "Native Beach Assessment Techniques for Beach Fill Design[3]" and "Recommended Physical Data Collection Program for Beach Nourishment Projects[4]"; the Corps of Engineers and the Environmental Protection Agency jointly prepared testing procedures for water and sediment samples and for ocean disposal of dredge material[5]^,[6] (informally called the "Green Book"); color can be judged from Munsell tables developed for soil scientists[7]; the National Research Council published a book on beach nourishment with a chapter dedicated to monitoring[8]; and there are countless journal articles reporting on the performance of specific nourishment efforts. If an analyst has a large beach nourishment project and must develop all the components of a monitoring effort, they should search for some recent articles on nourishment monitoring, and review some of the above mentioned material. Technical data bases have been prepared for the San Francisco and San Diego offices (and these data bases are available to the other area offices) to direct an analyst to some of these reports; the Technical Services Unit may be able to identify the most useful material for the specific project and should be contacted early in the effort.

Some typical questions about beach nourishment projects which could be addressed through monitoring are provided below. Nourishment projects vary greatly from one project to another. Nourishment material can be placed onshore or in the near shore environment, or both, and source material can be from a variety of on- and offshore locations. Whenever material is placed in "waters of the US," the Corps of Engineers must issue a permit for nourishment. IF the proposed nourishment will involve placement of any material in the "waters of the US," the analyst should contact the Corps of Engineers to determine the types of testing and monitoring that will be required for the Corps permit and to insure that state and federal efforts are coordinated.

(Verification that the wall construction followed the approved design and identification of as-built changes)

Usually, the contractor can make a determination about whether the nourishment project was built according to the design which was approved in the permit. The applicant can be required to provide a copy of the approved project description with the bid documents, and to obtain from the contractor a statement which either verifies that the final project conforms with the approved project or identifies all ways in which the final project differs from that which was approved. Project changes could be noted on a copy of the project plans or through new as-built plans. If the nourishment material were placed on the dry beach, the analyst can check this information independently, measuring the exposed dimensions with a tape measure or by pacing it off. The texture and color can be determined through visual inspection; detailed grain size analysis[9] and Munsell Color analysis[10] will require laboratory equipment and charts which is not now available in any of the Commission offices. If the nourishment material was placed in an offshore berm, it will be difficult for an analyst to measure or confirm any of the as-built conditions of the project. In these cases, the analyst may have to rely fully on information from the contractor.

In many nourishment projects, especially if the material is coming from a dredge project or from sediment traps, the proposed project may describe the amount of nourishment material as a range, rather than providing an exact quantity. In these cases, the analyst should obtain information on the final amount of material that was actually added to the beach. The contractor should be able to provide this information. If the material has all been placed on dry beach, the analyst can make a rough check of the quantity of material by measuring the dimensions of the new material — length, depth and width — and approximate the total volume (converting from cubic feet to cubic yards by dividing cubic feet by 27).

Most monitoring of long-term beach conditions following a beach nourishment effort will require licensed surveyors or other professionals with expertise in beach surveying and bathymetry. This is certainly true if the initial material were placed in a nearshore berm since the first evidence of sediment movement will occur at the berm.

Monitoring beach conditions after a beach is nourished normally requires some baseline information of the beach conditions prior to the nourishment project. Beach width and slope should be measured prior to the nourishment project, measured at various identifiable locations, spaced regularly along the beach, at the nourishment location and at downcoast locations. The pre-project measurements should be similar to, or more extensive than the post-project measurements which will be undertaken. For example, if the post-project monitoring is concerns only with available dry beach width, the pre-project measurements could use either dry beach width measurements or full profiles to closure depth. However, if the post-project is concerns with sand transport throughout the littoral cell and will require full profiles to closure, it would not be useful to have only dry beach width for the pre-project measurements.

If dry beach area is a concern, the measurements can be made using a tape measure, measuring from a stable location such as the base of a bluff, a seawall, the seaward extent of vegetation, or other easily identified location, to a seaward limit such as the wetted bound. The same locations should be measured regularly, every few months, for a given period of time. (For example, four or six times a year for five or ten years, until the area is renourished or possibly for as long as there is some evidence of nourishment material at the beach site.) It is important that the year to year measurements be taken in the same way, at the same shoreline locations and during the same time period, such as always during the same season, month, or two week period.

If there is concern about overall long-shore transport, the beach measurements should provide profiles from the back beach to a near-shore point, such as depth of closure. Such measurements must be undertaken by licensed surveyors with expertise in both land and bathymetric surveys. Likewise, if the concern is for changes in beach slope, the measurements should be made by professional surveyors. The critical elements that should be described in the monitoring plan would be the locations of the surveys, timing of the surveys, and their frequency.

Timing for monitoring should take into consideration the expected performance of the nourishment project. For a project where all the material has been placed on the beach, it would be reasonable to expect that a lot of material will move off shore as soon as it is attacked by waves, since the underwater portion of the beach would be greatly out of balance with portion of the beach that is above the water. Once this initial shift of material has occurred, it would be reasonable to expect that the beach would change at a rate similar to neighboring areas. For such situations, it may be useful to undertake rather frequent monitoring initially and reduce the frequency as the changes become more gradual. For nourishment undertaken as a nearshore berm, there may be no changes to the beach until wave action has worked the berm and moved sediment shoreward. It may be enough to monitor the berm every few months and monitor the beach twice a year to establish a seasonal pattern and be able to separate beach changes caused by the new material from those caused by seasonal changes.

More than other types of shoreline protection, beach nourishment is often undertaken as a way to improve a beach — add more dry beach, improve access, protect buried areas or back beach structures, enhance recreation, etc. The performance efforts will vary for each project; however, in many cases it may be appropriate to monitor the identified benefit and see if it is really achieved. Some questions which could be answered by monitoring are:

Changes to beach area were discussed previously. The other changes may require targeted user surveys or regular inspections for use. Turbidity concerns may require regular water quality testing or water quality testing during times when turbidity might be a critical concern, such as during lobster season, during times that the beach is used by sight feeding birds, etc. If the beach is part of a federal, state, regional or local park system, there may be beach personnel available to provide a general impression on the benefits or increase in use that has come from the nourishment effort. If no such group exists or is not able to provide help for a user survey, an independent survey may be necessary. For example, when there was uncertainty over the expected impacts to surfing from a new groin, the applicant was required to undertake a surfing survey[11]F.

Whenever there is monitoring of project performance, the analyst should have a general idea about what will be done with the information. The surfing condition mentioned above led to a conclusion that there had been adverse effects to surfing which could directly and objectively be attributed to the new groin. Several years of negotiations over mitigation followed because the condition had required that applicant would undertake appropriate mitigation, but there was no direction about what the mitigation might be or how it might occur. The "so what" part of monitoring needs to be considered if the focus of monitoring is to determine if there are any long-term effects which were not addressed in the original staff report and permit.

California Coastal Commission

Procedural Guidance Document: Monitoring

A Note on the Use of This Document

Table of Contents

SHORELINE PROTECTION AND BEACH NOURISHMENT PROJECTS

VERTICAL SEAWALL

Revetment

Cave Filling

Groin or Jetty

Beach Nourishment

Footnotes