Apddx_Am1_Morro_Bay_Harbor_Sampling_and_Analysis_Report_Nov2013.pdf

SAMPLING AND ANALYSIS REPORT

Morro Bay Harbor Geotechnical and Environmental Investigation Project Sampling, Bulk Sediment Chemistry, Geotechnical and Suitability Determination Results

Task Order No. 0004, USACE Contract No. W912PL-11-D-0015

Prepared for:

U.S. Army Corps of Engineers

Los Angeles District Los Angeles, California

Prepared by:

Diaz•Yourman – GeoPentech – Kinnetic Laboratories/ Joint Venture 1616 E. 17th Street

Santa Ana, CA 92705

November 2013

GeoPentech i

DISTRIBUTION LIST

Mr. Jeffrey Devine, Technical Manager U. S. Army Corps of Engineers, Los Angeles District Jeffrey.D.Devine@usace.army.mil

Ms. Krista Van Eyck Field Geotechnical Leader Diaz Yourman krista@diazyourman.com

Mr. Blake Horita, Project Manager U. S. Army Corps of Engineers, Los Angeles District

(213) 452-3401 Blake.M.Horita@usace.army.mil

Mr. Christopher Diaz Geotechnical Manager Diaz Yourman & Associates chris@diazyourman.com

Mr. Kirk Brus, Environmental Manager U. S. Army Corps of Engineers, Los Angeles District Kirk.C.Brus@usace.army.mil

Mr. Allen Yourman Joint Venture Project Manager Diaz Yourman Associates, Geopentech, and Kinnetic Laboratories Joint Venture Allen@diazyourman.com

Ms. Gail Campos, Ecologist U. S. Army Corps of Engineers, Los Angeles District Gail.M.Campos@usace.army.mil

Mr. Ken Kronschnabl KLI Project Manager Kinnetic Laboratories, Inc.

kkronsch@kinneticlabs.com

Mr. Peter Von Langen Los Angeles Regional Water Quality Control Board pvonlangen@waterboards.gov

Mr. Spencer Johnson Field Operations Manager Kinnetic Laboratories, Inc.

sjohnson@kinneticlabs.com

Mr. Allan Ota United States Environmental Protection Agency- Region 9 ota.allan@epa.gov

Mr. Marty Stevenson KLI QA/QC Management Kinnetic Laboratories, Inc.

mstevens@kinneticlabs.com

Mr. Dan Swenson U.S. Army Corps of Engineers Regulatory Division daniel.p.swenson@usace.army.mil

Mr. Jon Toal Health and Safety Management Kinnetic Laboratories, Inc.

jtoal@kinneticlabs.com

Mr. Larry Simon Federal Consistency Coordinator Energy, Ocean Resources and Federal California Coastal Commission lsimon@coastal.ca.gov

Mr. Bob Stearns Client Services Director Calscience Environmental Laboratories, Inc.

BStearns@calscience.com ii

Morro Bay Harbor Geotechnical and Environmental Investigation Project

Sampling, Bulk Sediment Chemistry, Geotechnical and Suitability Determination Results

Task Order No.0004, USACE, Contract No. W912PL-11-D-0015

TABLE OF CONTENTS

Page No.

1.0 INTRODUCTION

1.1 Project Summary

1.2 Site Location

1.3 Roles and Responsibilities

2.0 SITE HISTORY AND HISTORICAL DATA REVIEW

2.1 Harbor Construction, Site Setting and Potential Sources of Contamination

2.2 Previous Morro Bay Harbor Dredging and Testing Episodes

3.0 METHODS

3.1 Dredge Design

3.2 Study Design

3.2.1 Morro Bay Harbor Sediment Collection and Chemical Testing

3.2.2 Nearshore Area immediately Off of Montana de Oro State Beach and Morro Strand State

Beach Reference Samples

3.2.3 Geotechnical Samples and Testing

3.2.4 Summary of Morro Bay Harbor Testing and Evaluation Sequence

3.2.5 Physical Evaluation Guidelines

3.2.6 Chemical Evaluation Guidelines

3.3 Background Arsenic Samples

3.4 Field Sampling Protocols

3.4.1 Positioning and Depth Measurements

3.4.2 Vibracore Sampling Methods

3.4.3 Vibracore Decontamination

3.4.4 Core Processing

3.4.5 Beach Transect and Nearshore Area Grab Samples

3.4.6 Detailed Soils Log

3.4.7 Documentation and Sample Custody

3.5 Laboratory Testing Methods

3.5.1 Geotechnical Testing

3.5.2 Bulk Sediment Chemical Analyses

4.0 RESULTS

4.1 Sediment Physical Results

4.2 Sediment Chemical Results

4.3 Sediment and Receiving Beach Arsenic Results

5.0 DISCUSSION

5.1 Sediment Observations

5.2 Sediment Grain Size

5.3 Bulk Sediment Chemistry

5.4 Conclusions

iii

6.0 QUALITY CONTROL SUMMARY

6.1 Field Sampling Quality Management

6.2 Analytical Chemistry QA/QC

7.0 REFERENCES CITED

APPENDICES

APPENDIX A – Summary Results from the 2008 Morro Bay Harbor Dredge Material

Geotechnical and Environmental Investigation (Kinnetic Laboratories and Diaz- Yourman and Associates, 2008)

APPENDIX B – 2008 Morro Bay Soils Logs and Geotechnical Data APPENDIX C – 2013 Grain Size Compatibility Analyses (LA District USACE) APPENDIX D – 2013 Arsenic Investigation Report APPENDIX E – 2013 Core Photographs APPENDIX F – 2013 Soils Logs APPENDIX G – 2013 Analytical Laboratory Report APPENDIX H – 2013 Field Data Log Sheets APPENDIX I – 2013 Geotechnical Data APPENDIX J – 2013 Analytical Laboratory QA/QC Evaluation

LIST OF TABLES

Page No.

Table 1. Project Team and Responsibilities Table 2. Key Project Contacts Table 3. Site Maintenance Dredging History Table 4. Dredging Depths and Volumes Table 5. Sampling Locations, Core Depths, Mudline Elevations, and Sampling Elevations, Morro

Bay Harbor Table 6. Dates, Times and Sampling Coordinates for Samples Collected from the Montana de Oro

State Beach Nearshore Area and Morro Strand State Beach Table 7. Morro Bay Harbor Sediment Screening Values for Selected Analytes Table 8. Analytical Methods and Quantitation Limits for Achieved for the Sediment Samples Table 9. 2013 Moro Bay Harbor Sieve Analysis Data above Project or Overdredge Depth for Each

Individual Core Table 10. Vibracore Sample Location Gradation Test Results for Specific Sample Depth Intervals

Collected Below Project Depth or Overdepth, Morro Bay Harbor 2013 Sediment Investigation Table 11. 2013 Sieve Analysis Data for Montana de Oro State Beach Nearshore Area Locations and

Morro Strand State Beach Transect Locations Table 12. 2013 Morro Bay Harbor Bulk Sediment Chemistry Results Table 13. Quality Control Summary for Field Sediment Sampling Table 14. Counts of QC records per Chemical Category iv

LIST OF FIGURES

Page No.

Figure 1. Location of Morro Bay Harbor and Receiving Beaches Figure 2. Morro Bay Harbor Spring 2012 Bathymetric Data, Proposed 2013 Sampling Locations, and

Limits of Kelp and Eelgrass Beds for all Dredge Areas except the Southern Extent of the Morro Channel

Figure 3. Spring 2012 Bathymetric Data, Proposed 2013 Sampling Locations, and Limits of Eelgrass Beds for the Southern Extent of the Morro Channel, Morro Bay Harbor

Figure 4. April 2012 Bathymetric Data and Sampling Locations for the Modified Entrance Channel (Area A)

Figure 5. April 2012 Bathymetric Data and Sampling Locations for the Sand Trap and Transition Aream(Areas B and C)

Figure 6. April 2012 Bathymetric Data and Sampling Locations for the Main Channel (Area D) Figure 7. April 2012 Bathymetric Data and Sampling Locations for the Navy Channel (Area E) Figure 8. April 2012 Bathymetric Data and Sampling Locations in the Northern Morro Channel

(Area F) Figure 9. April 2012 Bathymetric Data and Sampling Locations in the Southern Morro Channel

(Area F) Figure 10. Location of and the Primary Placement Area Nearshore Immediately off of Montana de

Oro State Beach and the Alternative Placement Area at Morro Strand State Beach Figure 11. Sampling Locations at the Montana de Oro State Beach Nearshore Placement Area Figure 12. Sampling Tran v

LIST OF ACRONYMS

ASTM American Society for Testing and Materials MSD Minimum Significant Difference BLK Method or Procedural Blank ND Not Detected BMP Best Management Practice NOAA National Oceanic and Atmospheric Administration BS Blank Spike OEHA Office if Environmental Hazard Assessment BSD Blank Spike Duplicate PAH Polyaromatic Hydrocarbon Cal/EPA California Environmental Protection Agency PCB Polychlorinated Biphenyl CD Compact Disc PDS Post Digestion Spike CDFG California Department of Fish and Game PDSD Post Digestion Spike Duplicate CESPD Corps of Engineers South Pacific Division PPB Parts Per Billion CHHSL California Human Health screening Level PPM Parts Per Million COC Chain of Custody PRG Preliminary Remediation Goals CSLC California State Lands Commission PVC Polyvinyl Chloride CV Coefficient of Variation RBC Risk-Based Concentration cy Cubic Yards RL Reporting Limit CRM Certified Reference Material RPD Relative Percent Difference

DDD Dichlorodiphenyldichloroethane RSLs Regional Screening Levels for Cleanup of Superfund Sites

DDE Dichlorodiphenyldichloroethylene SC- DMMT Southern California Dredge Material Management Team

DDT Dichlorodiphenyltrichloroethane SCOUP Sand Compatibility and Opportunistic Use Plan DGPS Differential Global Positioning Satellite SOPs Standard Operating Procedures DTSC Department of Toxic Substances Control SRM Standard Reference Material DUP Laboratory Replicates STLC Title 22 Soluble Threshold Limit Concentration ERL NOAA Effects Range Low SURR Surrogate Analysis ERM NOAA Effects Range Medium SWQCB State Water Resources Control Board GPS Global Positioning Satellite TMDL Total Maximum Daily Log

HHMSSL Human Health Medium – Specific Screening Levels TOC Total Organic Carbon

HDPE High-density Polyethylene TRPH Total Recoverable Hydrocarbons ITM Inland Testing Manual TTLC Title 22 Total Threshold Limit Concentration LCL Lower Control Limit UCL Upper Control Limit LCS Laboratory Control Spike USACE U.S. Army Corps of Engineers LDPE Low-density Polyethylene USEPA U.S. Environmental Protection Agency LSD Least Significant Difference QA Quality Assurance MDL Method Detection Limit QC Quality Control MLLW Mean Lower Low Water QUAL Qualifier MS Matrix Spike USCS Unified Soil Classification System MSD Matrix Spike Duplicate vi

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Morro Bay Harbor Geotechnical and Environmental Investigation Project

Sampling, Bulk Sediment Chemistry, Geotechnical and Suitability Determination Results

Task Order No. 0004, USACE Contract No. W912PL-11-D-0015

EXECUTIVE SUMMARY

The United States Army Corps of Engineers (USACE) will be conducting annual routine maintenance dredging of the federal channels in Morro Bay Harbor in order to restore the channels back to their their design depths between -12 to -40 feet Mean Lower Low Water (MLLW). The volume of shoaled material based on a 2012 survey is 450,056 cubic yards (cy) with a two-foot overdredge allowance for non-advanced maintenance dredging areas only. This study was undertaken to evaluate the physical and chemical properties of the sediments within the Morro Bay Harbor channels in order to support planning and permitting for dredging and reuse. It is desired to reuse all of the Morro Bay Harbor sediments for beach replenishment at either the primary placement site nearshore immediately off of Montana de Oro State Beach or at an alternate location on the dry beach Morro Strand State Beach.

Vibracore sampling was carried out off the 38-foot vessel the Bonnie Marietta to collect subsurface sediment samples during the period of August 12 through 15, 2013. The vibracore was used at twenty-seven (27) locations throughout six (6) channel areas (Areas A through F). Each channel area represents a composite area except Areas C and D which were combined into one composite sample. Thus the 27 core locations sampled were combined into five composite samples.

Subsamples were combined with like subsamples in a composite area to form the five sediment composite samples. Each composite sample formed was analyzed for volatile solids, pH, TOC, oil & grease, TRPH, ammonia, sulfides, metals (arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, zinc), butyltins, pyrethroid pesticides, chlorinated pesticides, PCB congeners, phenols, phthalates, and PAH compounds. In addition, samples for grain size analyses and for archiving were collected from each of the individual cores prior to compositing. These grain size and archive samples represented the entire core length from the mudline to project depth for Areas A and B, and from the mudline to the two foot overdredge elevation for Areas C through E. No significant vertical grain size stratification was present in any of the individual cores (above the bottom sampling elevation).

To assist in evaluating beach suitability, a series of surface grab reference samples for physical observations and testing were collected on August 15, 2013 at eight locations at the primary nearshore placement site immediately offshore of Montana de Oro State Beach and along three transects at the alternate placement area on the dry beach at Morro Strand State Beach. Samples along each of the three transects were collected at eight elevations (+12, +6, 0, -6, -12, -18, -24, and -30 ft MLLW). All reference samples were tested for grain size distribution. These grain size gradation data were compared with grain size gradation data from the Morro Harbor samples by the Los Angeles District USACE to determine if the Harbor sediments are physically compatible with sand and sediment from the primary nearshore placement site immediately offshore of Montana de Oro State Beach and from the alternate placement site at Morro Strand State Beach. The USACE report (Appendix C) concluded that all of the sediments within the five channel areas are compatible for placement at the two preselected placement sites based on the weighted average of both the individual and composite sediment grain size curves for all core samples collected amongst each of the footprint areas.

Bulk sediment chemistry results were evaluated against NOAA effects-based screening levels and human health objectives. Only nickel in all five composite samples was elevated above NOAA’s lower effects-based screening values and only arsenic was elevated above human health objectives. The arsenic exceedances were investigated further to see if the Morro Bay Harbor sediment concentrations were elevated above an estimated background arsenic concentration for local beaches. This investigation came up with a local beach background concentration of 4.37 mg/kg (Appendix D), which is higher than the arsenic concentrations in the five composite samples (2.8 to 3.4 mg/kg). Furthermore, the position of the California Department of Toxic Substances Control (Dr. William Bosan, personnel communication) is that the risk to human health is minimal for arsenic concentrations below 12.0 mg/kg. Therefore, arsenic excursions above screening levels appear to be minor and the overall dataset indicates that there is little chance of increased adverse biological or human health effects from the placement of Morro Bay Harbor sediments at the primary area nearshore of Montana de Oro State Beach and at the alternative placement site on the dry beach at Morro Strand State Beach.

1.0 INTRODUCTION

Routine maintenance dredging is required on an annual basis for the federal channels of Morro Bay Harbor, California (Figure 1) in order to maintain the channels to design depths. Sediments to be dredged require an environmental evaluation of sediment quality in order to support planning and permitting for dredging and reuse. This project is authorized by 1958 Rivers and Harbors Act (H. DOC. 356, 90TH CONG. 2nd SESS).

This report has been prepared on behalf of the U.S. Army Corps of Engineers, Los Angeles District to describe results from the sampling and testing of sediments from Morro Bay Harbor identified for placement at two potential beach nourishment areas. This work is being performed under Task Order No.

0004, USACE Contract No. W912PL-11-D-0015. All work described in this report was done in accordance to the approved SAP (Diaz Yourman and Associates, GeoPentech and Kinnetic Laboratories Joint Venture, 2013).

The SC-DMMT reviewed the 2013 preliminary draft SAP during the SC-DMMT’s February 27, 2013 monthly meeting, and review comments from the USEPA were incorporated into the 2013 preliminary draft SAP. The SC-DMMT also reviewed the draft SAP with Appendices during the SC-DMMT July 24, 2013 meeting with no review comments received on the 2013 draft SAP or its appendices. During the July 24, 2013 SC-DMMT monthly meeting, the USEPA requested additional time for review of the appendices for the 2013 draft SAP, and agreed to submit their comments by July 31, 2013. These appendices included an appendix of previous 2008 summary test results from the 2008 Morro Bay Soils Log and Geotechnical Data. The USEPA responded on August 1 and stated the grain size data looked fine from 2008 sampling episode, and as such, the USEPA stated the compositing scheme is acceptable and no further comments were issued. As no new comments on the 2013 draft SAP or its appendices were received from the SC-DMMT, and since the SC-DMMT did not request an out of cycle meeting to approve the 2013 draft SAP with its appendices, the draft 2013 SAP with its appendices was finalized as the final SAP with its appendices on August 1, 2013. A copy of the final SAP dated August 2013 can be requested from the U.S. Army Corps of Engineers (USACE), Los Angeles District (LAD) from point of contact (POC) Kirk Brus, at e-mail address kirk.c.brus@usace.army.mil or by phone number (213) 452- 3876.

1.1 Project Summary

The purpose of this project was to sample and test sediments from within the federal channels proposed for annual maintenance dredging to provide sediment quality data for evaluation of dredging and beach nourishment. This report is to fulfill requirements of the Army Corps of Engineers South Pacific Division Regulation No. 1110-1-8 (CESPD, 2000), the Inland Testing Manual (ITM) (USACE and USEPA, 1998), the Clean Water Act (CWA), Southern California Dredge Material Management Team (SC-DMMT) draft guidelines, and in support of the new six year Environmental Assessment for the Morro Bay Harbor Federal Maintenance Dredging Project. Since arsenic is commonly found at elevated concentrations in ambient soils and dredged sediments, a secondary purpose of this project is to determine background arsenic concentrations for area beaches and determine if the Morro Bay Harbor sediments are elevated above beach background concentrations.

Based on a hydrographic survey conducted in the spring of 2012, the estimated volume of sediments needing to be dredged from the approximately 118 acres of Morro Bay Harbor Federal Navigation Channels at that time was 450,056 cubic yards (cy) including overdredge allowance. This quantity most likely has not changed much due to the offshore littoral drift of sediments into the Harbor despite annual dredging of the Modified Entrance Channel.

mailto:kirk.c.brus@usace.army.mil

Figure 1. Location of Morro Bay Harbor and Receiving Beaches.

Morro Strand State Beach

Montana de Oro State Beach

The primary proposed area for dredged material placement is the nearshore immediately off of Montana de Oro State Beach located south of Morro Bay Harbor. An alternative area for dredged material placement is on Morro Strand State Beach located north of Morro Bay Harbor. Approximate locations of both beaches are depicted on Figure 1. Placement of Morro Bay Harbor sediments in the nearshore or on the receiving beaches counteracts natural beach erosion and has historically improved the overall integrity of these beaches as this.

Morro Bay Harbor has been divided into six dredge areas based on location and design depths. These areas are the Modified Entrance Channel, Sand Trap, Transition Channel, Main Channel, Navy Channel and Morro Channel. Design depths for these channels range from -12 feet mean lower low water (MLLW) for the Morro Channel to -40 feet MLLW for the Modified Entrance Channel. The Modified Entrance Channel and Sand Trap are actually areas of advanced maintenance dredging to ward off more significant shoaling that could endanger vessels entering and leaving the Harbor.

A hopper dredge is used to dredge the Modified Entrance Channel, Transition Channel, Main channel, and portions of the Navy Channel on a mostly yearly basis. The Morro Channel and Sand Trap are dredged less frequently using a variety of means depending on the dredge contractor. In the past, these remaining areas have been dredged using hopper dredges, cutterhead dredges and other hydraulic dredges, and excavator dredges, or a combination of these dredges.

Portions of Morro Bay Harbor adjacent to the federal channels are inhabited by giant kelp and eelgrass.

These important habitats provide food and sanctuary for a variety of marine species and must be avoided by leaving a 100 foot berth during dredging and sampling activities. Sea otters also frequent Morro Bay Harbor and must also be avoided.

1.2 Site Location

Morro Bay Harbor is located in San Luis Obispo County, California (Figure 1). Geographic coordinates (NAD 83) for the Entrance to Morro Bay Harbor are 35° 21' 4" N and 120° 52' 07" W. The approximate center of the Harbor in front of the Coast Guard Pier is 35° 22' 0" N and 120° 51' 32" W. Geographic coordinates of the approximate center of the Montana de Oro State Beach nearshore placement area are 35° 20' 47" N and 120° 52' 21" W, and geographic coordinates of the approximate center of the Morro Strand State Beach placement are 35° 23' 20" N and 120° 51' 59" W.

1.3 Roles and Responsibilities

Project responsibilities and key contacts for this sediment characterization program are listed in Tables 1 and 2. Kinnetic Laboratories Inc. provided sampling and reporting services. Diaz Yourman and Associates provided core logging and geotechnical testing. Analytical chemical testing of sediments for this project was primarily carried out by Calscience Laboratories (NELAP No. 03220CA; Cal-ELAP No.

2803).

Table 1. Project Team and Responsibilities.

Responsibility Name Affiliation

Project Planning and Coordination

Jeffrey Devine Blake Horita

Christopher Diaz Ken Kronschnabl

USACE

USACE

Diaz-Yourman Kinnetic Laboratories

SAP Preparation Ken Kronschnabl Christopher Diaz

Kinnetic Laboratories Diaz-Yourman

Field Sample Collection and Transport Spencer Johnson Dale Parent

Kinnetic Laboratories Kinnetic Laboratories

Geotechnical Investigation Chris Diaz Krista Van Eyck

Diaz-Yourman Diaz-Yourman

Health and Safety Officer and Site Safety Plan Jon Toal Kinnetic Laboratories

Laboratory Chemical Analyses Danielle Gonsman Katie Scott

Calscience Kinnetic Laboratories

QA/QC Management Analytical Laboratory QA/QC

Marty Stevenson Danielle Gonsman

Kinnetic Laboratories Calscience

Technical Review

Pat Kinney Jeffrey Devine

Christopher Diaz Jeremy Jackson

Kirk Brus Joe Ryan

Kinnetic Laboratories

USACE

Diaz-Yourman

USACE

USACE

USACE

Final Report Ken Kronschnabl Christopher Diaz

Kinnetic Laboratories Diaz-Yourman

Agency Coordination

Jeffrey Devine Kirk Brus

Gail Campos Jeremy Jackson

Joe Ryan

USACE

USACE

USCAE

USACE

USACE

USACE = United States Army Corps of Engineers

Table 2. Key Project Contacts.

Blake Horita USACE Project Manager PPMD Navigation and Coastal Projects Branch U. S. Army Corps of Engineers, Los Angeles

District 915 Wilshire Blvd., Ste. 980 Los Angeles, Ca. 90017 Tel. (213) 452-3579.

Blake.M.Horita@usace.army.mil

Jeffrey Devine USACE Project Technical Manager Geology and Investigations Section U. S. Army Corps of Engineers, Los Angeles District 915 Wilshire Blvd. Ste. 980 Los Angeles, Ca. 90017 Tel. (213) 452-3579 Jeffrey.D.Devine@usace.army.mil

Kirk Brus Environmental Manager U. S. Army Corps of Engineers, Los Angeles

District Tel. (213) 452-3876 Kirk.C.Brus@usace.army.mil

Gail Campos Ecologist U. S. Army Corps of Engineers, Los Angeles

District Tel. (213) 452-3874 Gail.M.Campos@usace.army.mil

Chris Diaz Project Manager - Geotechnical Investigations Diaz.Yourman & Associates 1616 East 17th Street Santa Ana, CA 92705-8509 Tel. (714) 245-2920 chris@diazyourman.com

Ken Kronschnabl Project Manager - Sampling/Testing Kinnetic Laboratories, Inc. (KLI) 307 Washington St.

Santa Cruz, CA 95060 Tel. (831) 457-3950 kkronsch@kinneticlabs.com

Spencer Johnson Field Operations Mgr.

Kinnetic Laboratories, Inc. (KLI) 307 Washington St.

Santa Cruz, CA 95060 Tel. (831) 457-3950 sjohnson@kinneticlabs.com

Bob Stearns Client Services Director – Analytical Testing Calscience Environmental Laboratories, Inc.

7440 Lincoln Way Garden Grove, CA 92841-1427 Tel.: (714) 895-5494 x202 BStearns@calscience.com

Marty Stevenson KLI QA/QC Management Kinnetic Laboratories, Inc.

55-1 Puapake Pl.

Lahaina, HI 96761 Tel. (808) 661-1110 mstevens@kinneticlabs.com

Allen Yourman Joint Venture Project Manager Diaz Yourman Associates, Geopentech, and Kinnetic Laboratories Joint Venture 1616 East 17th Street Santa Ana, CA 92705-8509 Tel. (714) 245-2920 Allen@diazyourman.com mailto:Allen@diazyourman.com

2.0 SITE HISTORY AND HISTORICAL DATA REVIEW

This section provides a brief history of Morro Bay Harbor, potential sources of contamination, dredging history, and most recent previous testing and sampling results.

2.1 Harbor Construction, Site Setting and Potential Sources of Contamination

Morro Bay Harbor is located in San Luis Obispo County (Figure 1) at the mouth of a natural embayment.

It was first established as a Port in 1870 to export dairy and ranch products. It is now an artificial harbor constructed by the U.S. Army Corps of Engineers (USACE). Morro Rock, bordering the northwest corner of the Harbor, was originally an island until USACE constructed a causeway connecting the island to the mainland starting in 1933. Prior to the causeway, the entrance to the Harbor was from the north, east of Morro Rock. Morro Rock was quarried from 1889 to 1969 and some of that material was used to build the causeway. During World War II, the USACE built the outer breakwater to protect the new entrance to the Harbor. To improve safety for vessels entering and leaving the Harbor, the Entrance Channel was deepened and extended in 1995.

The Harbor is bounded by a long sand spit with no development to the west and the City of Morro Bay to the east. Most of the surrounding land use to the east of Morro Bay Harbor is residential and commercial.

There is a 300 megawatt power plant operated by Dynegy along the northern shore of Morro Bay Harbor east of Morro Rock. The plant pumps cooling water from the Harbor and discharges it to the Pacific Ocean north of Morro Rock. The power plant currently only operates during periods of peak energy demand. There are no other major industrial facilities in the Morro Bay Harbor watersheds, and it is not known if such facilities existed in the past.

Chorro Creek is Morro Bay’s largest tributary. It forms an estuary in the back bay between Morro Bay Harbor and the town of Los Osos. Los Osos Creek empties into the far south end of the back bay and is the second largest and only other significant tributary. The Chorro Creek watershed, which is dominated by rangeland with areas of woodland, cropland, and urban land use, has been issued total maximum daily loads (TMDLs) for nutrients and dissolved oxygen. Morro Bay itself, which includes Chorro Creek and Los Osos Creek, also has TMDLs for sediment and pathogens.

There are several marinas in Morro Bay Harbor with the largest operated by the City of Morro Bay. The City manages 50 slips, approximately 125 moorings, a boat launch facility, and couple of city piers. As many as 50 liveaboards are permitted to stay in Morro Bay Harbor. The Harbor also contains a fuel dock, a couple boat yards with haul out facilities, and fish processing facilities.

According to the City of Morro Bay’s Storm Water Management Plan (City of Morro Bay, 2011) there are about 18 small storm drains (<36 inches in diameter) that discharge into Morro bay Harbor. These discharges are spread out fairly evenly along the entire waterfront.

Portions of Morro Bay Harbor adjacent to the federal channels are inhabited by giant kelp and eelgrass.

These important habitats provide food and sanctuary for a variety of marine species. As such, it is important to avoid damage to these habitats during dredging and sampling activities by leaving a 100 foot berth.

The proposed receiving beaches: nearshore immediately off of Montana de Oro State Beach (primary) and on the dry beach at Morro Strand State Beach (alternative), are directly to the north and south of Morro Bay Harbor as shown in Figure 1. Both beaches are west facing and receive considerable wave energy. Placement of Morro Bay Harbor sediments on or nearshore of the receiving beaches has historically improved the overall integrity of these beaches by counteracting natural erosion.

2.2 Previous Morro Bay Harbor Dredging and Testing Episodes

USACE maintains the federal channels of Morro Bay Harbor to their design depths. Portions of the channels have been dredged almost annually for the past 30 years. Table 3 describes the dredging history from 1986 to the present. The Entrance Channel, Transition Channel, Main channel and portions of the Navy Channel are dredged most often while the Morro Channel and Sand Trap are dredged only occasionally with the last harbor-wide dredging occurring in 2009/2010.

The most recent full array of physical and chemical sampling and analyses for the Morro Bay Harbor federal channels occurred in 2008. A total of 19 core samples were collected to project depths plus two feet and analyzed for grain size distribution. Data from these analyses were compared to the grain size distribution of sediments from the primary nearshore placement area immediately offshore of Montana de Oro State Beach and along three transects at the alternative placement area at Morro Strand State Beach to determine the physical suitability of Morro bay Harbor sediments for beach nourishment. In addition, representative portions of the 19 cores were combined into six composite samples for bulk sediment chemical testing to determine if the Harbor sediments are environmentally suitable for beach nourishment. Results of this study are summarized in a report by Kinnetic Laboratories and Diaz- Yourman and Associates (2008). Summary sampling and chemical testing data from this study are provided in Appendix A. Geotechnical testing data and soils logs from this study are provided in Appendix B.

In 2008, the Morro Bay Harbor sediments consisted primarily of sand and only low levels of contaminants were evident. Most organic contaminants were not detected above reporting limits in any samples. The only detectable organic contaminates were low levels of PAH compounds. With the exception of nickel, all metal concentrations were below NOAA lower effects based screening levels (ERL values from Long et. al., 1995). Nickel levels exceeded the lower effects based screening value in five of the six composite samples. The NOAA upper effects based screening value (ERM) for nickel was also exceeded in one of the Navy Channel composite samples. Note that the confidence in NOAA screening values for nickel is low. It was found that the incidence of toxic effects do not increase appreciably with increasing concentrations of nickel (Long et al., 1995). Based on the high sand content and low levels of contaminants found, these sediments were determined to be acceptable for beach replenishment. The dredged material from 2008 to the present has annually been discharged to the primary dredged material placement site in the nearshore immediately off of Montana Do Oro State Beach. Material was discharged to the alternate site in the beach surf zone along Morro Strand State Beach during the Harbor-wide maintenance dredging episode in 2009/2010.

A study conducted in 2001 (Kinnetic Laboratories, 2001) also showed that the Morro Bay Harbor sediments were coarse grained and generally clean and this study also resulted in a positive suitability determination. The dredged material was discharged to both the primary and alternative dredged material placement sites.

Table 3. Site Maintenance Dredging History.

Period Location Design Depths

(ft. MLLW)

Volume Removed

(cy)

Placement Location Dredge Type

May – June

M.E., S.T., Trans., Main, Navy -40, -24, -16 122,850 Montana de Oro

SB Nearshore Hopper

May 2012 M.E., S.T., Trans., Main, Navy -40, -24, -16 125,000 Montana de Oro

SB Nearshore Hopper

May – June

M.E., S.T., Trans., Main, Navy -40, -24, -16 120,920 Montana de Oro

SB Nearshore Hopper

Aug. – Sept.

M.E., S.T., Trans., Main -40, -24, -16 135,170 Montana de Oro

SB Nearshore Hydraulic

May – June

M.E., S.T., Trans., Main, Navy -40, -24, -16 249,780 Montana de Oro

SB Nearshore Hopper

2009/2010

M.E., S.T., Trans., Main, Navy -40, -25, -16 375,000 SB Hydraulic

Morro -12 199,000 Montana de Oro SB Nearshore Excavator (Bucket)

June 2009 M.E., S.T., Trans., Main, Navy -40, -24, -16 151,070 Montana de Oro

SB Nearshore Hopper

June – July

M.E., S.T., Trans., Main, Navy -40, -24, -16 140,800 Montana de Oro

SP Nearshore Hopper

July 2007 M.E., S.T., Trans., Main, Navy -40, -24, -16 150,400 Montana de Oro

SB Nearshore Hopper

July 2006 M.E., S.T., Trans., Main, Navy -40, -24, -16 196,250 Montana de Oro

SP Nearshore Hopper

July 2005 M.E., S.T., Trans., Main, Navy -40, -24, -16 134,000 Montana de Oro

SB Nearshore Hopper

July 2004 M.E., S.T., Trans., Main, Navy -40, -24, -16 155,700 Montana de Oro

SB Nearshore Hopper

July 2003 M.E., S.T., Trans., Main, Navy -40, -24, -16 170,820 Montana de Oro

SB Nearshore Hopper

2001/2002 M.E., S.T., Trans., Main, Navy -40, -24, -16 657,000 Montana de Oro SB Nearshore Hydraulic

Morro -12 211,500 Morro Strand SB Cutterhead

July 2001 M.E., S.T., Trans., Main, Navy, Moro

-40, -25, -24, -16, -12 180,470 Montana de Oro

SB Nearshore Hopper

July – Aug.

2000 M.E., Trans., Main -40, -24, -16 236,900 Montana de Oro

SB Nearshore Hopper

June – July 1999 M.E., Trans., Main -40, -24, -16 134,230 Montana de Oro

SB Nearshore Hopper

Aug. 1998 M.E., Trans., Main -40, -24, -16 115,390 Montana de Oro SB Nearshore Hopper

Jan. – April, M.E., S.T., Trans., Main, Navy, Moro

-40, -25, -24, -16, -12 555,900

Montana de Oro SB Nearshore & Morro Strand SB

Hopper

1997 M.E. -40 63,000 Montana de Oro SB Nearshore Hopper

Table 3. Site Maintenance Dredging History.

Period Location Design Depths

(ft. MLLW)

Volume Removed

(cy)

Placement Location Dredge Type

1995 -1996 M.E., S.T., Trans., Main, Navy -40, -24, -16 1,041,000

Montana de Oro SB Nearshore & Morro Strand SB

Hopper

1994 M.E., Trans., Main, Navy -40, -24, -16 555,900

Montana de Oro SB Nearshore & Morro Strand SB

Hopper/ Cutterhead

1992a M.E. -40 120,330 Montana de Oro SB Nearshore & Morro Strand SB

Cutterhead

1990 M.E., Trans., Main, Navy, Morro

-40, -24, -16, -12 475,300 Montana de Oro

SB Nearshore Hopper

1986/1987 460,400

* This dredging episode was done on an emergency basis and was not considered maintenance dredging.

M.E. = Modified Entrance Channel S.T. = Sand Trap (advanced maintenance dredge area) Trans. = Transition Channel Main = Main Channel Navy = Navy Channel Morro = Morro Channel SB = State Beach

3.0 METHODS

This section describes the dredging design, study design and field and analytical methods for this testing program.

3.1 Dredge Design

Contoured bathymetric data from the spring of 2012 are shown on Figures 2 and 3. These figures identify each of the channel areas described in Section 1.1 along with their design depths. Figures 4 through 9 are additional close-up maps showing more legible point bathymetric data from the spring of 2012 for each of the channel areas in relationship to proposed sampling locations. Design depths and dredge volumes for each area identified for dredging are provided in Table 4.

The Morro Bay Harbor kelp and eelgrass beds have been mapped over the past several years and these maps can be used to assist contractors in avoiding damage to these areas. Mapping data are included in Figures 2 and 3. The distribution of the main kelp bed also known as the Target Rock kelp bed is primarily adjacent to Morro Rock and along the northwest side of the Main Channel, with scatterings of kelp to the north and south of the Target Rock bed. The distribution of the main eelgrass beds extends from Morro Rock to the Morro Channel along the north and south sides of the Navy Channel.

3.2 Study Design

The study design for this project covers data collection tasks for Morro Bay Harbor sediment collection and testing and Montana de Oro State Beach nearshore area and Morro Strand State Beach sampling and geotechnical testing. Evaluation guidelines are also discussed.

The main approach used was to sample Morro Bay Harbor sediments to dredge depth plus overdredge, composite them by area, and subject the composite samples to chemical testing to determine if they are suitable for beach nourishment. The approach was also to determine the physical properties of the sediments at each location and at different depths. Testing followed requirements and procedures detailed in the ITM (USEPA/USACE, 1998) with further guidance from Los Angeles District USACE guidelines (CESPL, undated) and from SC-DMMT draft guidelines. Acceptability guidelines published in these documents were used to evaluate the suitability of Morro Bay Harbor maintenance-dredged sediments for beach nourishment.

3.2.1 Morro Bay Harbor Sediment Collection and Chemical Testing

Vibracore sampling, as described in Section 3.4.2 (Vibracore Sampling Methods), was carried out during the period of August 12 to August 15, 2013 to collect subsurface sediment data at four (4) locations within Area A (Modified Entrance Channel), four (4) locations within Area B (Sand Trap), one (1) location within Area C (Transition Area), two (2) locations within Area D (Main Channel), nine (9) locations within Area E (Navy Channel), and seven (7) locations in Area F (Morro Channel). In total, there were 27 separate vibracore sampling locations for the Morro Bay Harbor federal maintenance dredging channel areas. The prefix for all locations is “MBHVC13-#-##.” Final sampling locations are shown on Figures 2 through 9. All cores were advanced to project elevations or overdepth elevations, depending on the area. Date and time of collection, final coordinates, approximate seafloor elevations, and sampling elevations for the sample locations are listed in Table 5. Note that some sample locations were moved to target more shoaled areas and avoid kelp beds and eelgrass beds. Best Management Practices (BMPs) during sampling activities were used to avoid the kelp and eelgrass habitats to the extent practicable.

Table 4. Dredging Depths and Volumes.

Dredge Area

Composite Area Location Physical Area

(Acres) Design Depth (ft., MLLW)

Design Depth + Overdredge (ft., MLLW)

Approximate 2012 Design Depth

Volume (Cubic Yards)

Allowable Overdepth Volume

(Cubic Yards)

Dredge Volume with Allowable

Overdredge (Cubic Yards)

A A Modified Entrance Channel 15.1 -40 -40 230,300 0 230,300

B B Sand Trap 8.0 -25 -25 34,520 0 34,520 C

C/D Transition Area 4.0 -16 to -40 -18 to -42 9,160 5,930 15,100

D Main Channel 14.4 -16 -18 22,410 8,570 30,980 E E Navy Channel 45.4 -16 -18 60,490 39,500 100,000 F F Morro Channel 30.7 -12 -14 11,790 27,350 39,140

Total Volume 368,670 81,350 450,040

Figure 2. Morro Bay Harbor Spring 2012 Bathymetric Data, Proposed 2013 Sampling Locations, and Limits of Kelp and Eelgrass Beds for all Dredge Areas except the Southern Extent of the Morro Channel.

Area A Area B

Area C/D

Area E

Area F

Figure 3. Spring 2012 Bathymetric Data, Proposed 2013 Sampling Locations, and Limits of Eelgrass Beds for the Southern Extent of the Morro Channel, Morro Bay Harbor.

Area F

Figure 4. April 2012 Bathymetric Data and Sampling Locations for the Modified Entrance Channel

(Area A).

Figure 5. April 2012 Bathymetric Data and Sampling Locations for the Sand Trap and Transition Aream(Areas B and C).

Figure 6. April 2012 Bathymetric Data and Sampling Locations for the Main Channel (Area D).

Figure 7. April 2012 Bathymetric Data and Sampling Locations for the Navy Channel (Area E).

Figure 8. April 2012 Bathymetric Data and Sampling Locations in the Northern Morro Channel

(Area F).

Figure 9. April 2012 Bathymetric Data and Sampling Locations in the Southern Morro Channel

(Area F).

Table 5. Sampling Locations, Core Depths, Mudline Elevations, and Sampling Elevations, Morro Bay Harbor.

Composite Area

Core Designation Composite ID

Sampling Date

Sampling Time Latitude

North Longitude

West

Mudline Elevation

(ft., MLLW)

Design Depth +

Overdepth (ft., MLLW)

Core Recovery

(ft.)

Core Intervals Sampled

(ft., MLLW)

Area A Modified Entrance Channel

MBHVC13- 1

MBHVC13- A

8/15/13 0956 35.36003° 120.87033° -33.5 -40 10 -33.5 to -40 MBHVC13-2 8/15/13 0827 35.36058° 120.87128° -36.1 -40 9 -36.1 to -40 MBHVC13-3 8/15/13 0907 35.36182° 120.87104° -34.8 -40 8.9 -34.8 to -40 MBHVC13-4 8/15/13 1043 35.36129° 120.86931° -33.5 -40 8.1 -33.5 to -40

Area B Sand Trap

MBHVC13-5

MBHVC13- B

8/13/13 0915 35.36266° 120.86702° -19 -25 14 -19 to -25 MBHVC13-6 8/13/13 0800 35.36255° 120.86686° -19.3 -25 14.5 -19.3 to -25 MBHVC13-8 8/13/13 1020 35.36377° 120.86683° -19 -25 13.7 -19 to -25 MBHVC13-9 8/13/13 1104 35.36408° 120.86622° -22 -25 13.3 -22 to -25

Areas C/D Transition Area/Main Channel

MBHVC13-7

MBHVC13- C/D

8/12/13 1545 35.36401° 120.86790° -25 -26 13.2 -25 to -26 MBHVC13-10 8/12/13 1816 35.36534° 120.86562° -15 -18 13.0 -15 to -18 MBHVC13-11 8/13/13 1328 35.36656° 120.86502° -15.1 -18 10.6 -15.1 to -18

Area E Navy

Channel

MBHVC13-12

MBHVC13- E

8/13/13 1204 35.36704° 120.86453° -15.5 -18 12.4 -15.5 to -18 MBHVC13-13 8/13/13 1536 35.36989° 120.86152° -17.2 -18 13.8 -17.2 to -18 MBHVC13-14 8/13/13 1449 35.37110° 120.86225° -14.2 -18 9.9 -14.2 to -18 MBHVC13-15 8/13/13 1628 35.37177° 120.86071° -15.1 -18 12.6 -15.1 to -18 MBHVC13-16 8/13/13 1732 35.37014° 120.85986° -12.9 -18 13.6 -12.9 to -18 MBHVC13-17 8/13/13 1810 35.36985° 120.85885° -16.1 -18 9.5 -16.1 to -18 MBHVC13-18 8/14/13 0812 35.36955° 120.85843° -15.2 -18 13.0 -15.2 to -18 MBHVC13-19 8/14/13 0846 35.36883° 120.85741° -13.2 -18 11.8 -13.2 to -18 MBHVC13-20 8/14/13 0936 35.36753° 120.85606° -13.0 -18 8.6 -13.0 to -18

Area F Morro

Channel

MBHVC13-21

MBHVC13- F

8/14/13 1538 35.36058° 120.85256° -10 -14 10.0 -10.0 to -14 MBHVC13-22 8/14/13 1449 35.35962° 120.85223° -11.3 -14 12.7 -11.3 to -14 MBHVC13-23 8/14/13 1401 35.35760° 120.85240° -12.6 -14 8.3 -12.6 to -14 MBHVC13-24 8/14/13 1318 35.35536° 120.84989° -10.8 -14 12.2 -10.8 to -14 MBHVC13-25 8/14/13 1234 35.35369° 120.84830° -10.6 -14 11.8 -10.6 to -14 MBHVC13-26 8/14/13 1107 35.35310° 120.84741° -9.3 -14 15.0 -9.3 to -14 MBHVC13-27 8/14/13 1039 35.35227° 120.84708° -8.5 -14 10.1 -8.5 to -14

A total of five (5) area composite samples were created from the six (6) channel areas shown on Figures 2 and 3 and analyzed for bulk sediment chemistry. Areas C and D (Transition Area and Main Channel) were combined into one of the composite samples. One composite sample was formed from each of the remaining areas. For primary beach placement suitability evaluations, continuous samples from the mudline to project depths plus two feet for overdredge testing were collected from locations within Areas C through F, and continuous samples from the mudline to project depths only (no overdredge) were collected from locations within Areas A and B. There is no overdredge allowance for Areas A and B since these are areas of advanced maintenance dredging. All primary core intervals were homogenized and then combined with like core intervals in a composite area for bulk sediment chemistry analyses.

Sediments below overdepth or advanced maintenance elevations were not included in any sediment composite samples for chemistry. Composite and overdepth elevations are summarized in Table 5.

In addition to the composite samples, a sample for arsenic and one archive bulk sediment chemistry sample were collected from each core location. The arsenic sample and one archive sample represented the entire primary core interval (mudline to project or overdepth elevations). All archive samples are being stored frozen for at least six months from the time of sampling unless directed otherwise by the USACE Technical Manager.

Core subsamples for geotechnical testing were from any geo-physically different layer of material not already being analyzed for grain size distribution as described below in Section 3.2.3.

3.2.2 Nearshore Area immediately Off of Montana de Oro State Beach and Morro Strand

State Beach Reference Samples

A series of surface grabs were collected on August 15, 2013 at eight (8) randomly placed locations in USACE’s primary placement area nearshore immediately offshore of Montana de Oro State Beach and along three (3) transects at the USACE’s alternate placement site on the dry beach at Morro Strand State Beach. These placement areas are shown on Figure 10. The eight randomly placed locations at the primary placement area were between mudline elevations of -20 and -40 MLLW. These locations are shown on the Google Earth™ image represented by Figure 11. The beach transect sampling consisted of collecting surface grab samples at eight elevations (+12, +6, 0, -6, -12, -18, -24 and -30 feet MLLW) along the three perpendicular transects. The three transects were located equidistance apart as shown on the Figure 12 Google Earth™ image of the sampling locations. Table 6 provides a list of the final locations for the nearshore placement area and beach transect samples.

3.2.3 Geotechnical Samples and Testing

A sufficient quantity of sediment was collected from each location within Morro Bay Harbor so that a representative amount of sediment was included in each geotechnical sample. A minimum of one primary grain size sample was formed and analyzed from each core. This sample represented the material from the mudline to the advanced maintenance depth for Areas A and B and to project overdredge depth for Areas C through F. If it existed, a separate sample was also collected from the “fluff” layer (top layer of finer grained material). Additional grain size samples representing layers of physically different material greater than six inches thick were selected amongst all the cores and also tested as needed or archived (set aside). Some of the finer-grained samples also underwent hydrometer and plasticity analyses. Decisions on which samples to analyze were made with input from the USACE Project Technical Manager.

Grain size analyses were also run on each sampling location for the Montana de Oro State Beach nearshore area and Morro Strand State Beach for a total of thirty-two (32) additional samples.

All mechanical grain size tests were run according to ASTM D 422 (1963). Hydrometer tests were run according to ASTM D 422 and Atterberg Limits tests were run according to ASTM D 4318 (2005).

Figure 10. Location of and the Primary Placement Area Nearshore Immediately off of Montana de Oro State Beach and the Alternative Placement Area at Morro Strand State Beach.

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Figure 11. Sampling Locations at the Montana de Oro State Beach Nearshore Placement Area.

B1

B5

B3

B2

B6

B7

B8

B4

B4

B8

B7

B6

B2

B3

B5

B1

Figure 12. Sampling Transect Locations at Morro Strand State Beach.

A (-30) A (-24)

A (-18) A (-12) A (-6) A (0) A (+6)

A (+12)

B (-30)

B (-24)

B (-18)

B (-12)

B (-6)

B (0)

B (+6)

B (+12)

C (-30)

C (-24)

C (-18) C (-12)

C (-6) C (0) C (+6)

C (+12)

Table 6. Dates, Times and Sampling Coordinates for Samples Collected from the Montana de Oro State Beach Nearshore Area and Morro Strand State Beach.

Area Site Designations Date Time

Sampling Elevations

(feet, MLLW)

Latitude North

Longitude West

Morro Strand Beach

Transect A

(MBBGS13-A)

A+12 (A1) 8/15/2013 15:01 +12 35° 23.763' 120° 52.032' A+6 (A2) 8/15/2013 15:04 +6 35° 23.76' 120° 52.07' A0 (A3) 8/15/2013 15:07 0 35° 23.758' 120° 52.103' A-6 (A4) 8/15/2013 14:15 -6 35° 23.75' 120° 52.2'

A-12 (A5) 8/15/2013 15:05 -12 35° 23.733' 120° 52.25' A-18 (A6) 8/15/2013 14:59 -18 35° 23.733' 120° 52.317' A-24 (A7) 8/15/2013 14:48 -24 35° 23.717' 120° 52.383' A-30 (A8) 8/15/2013 14:26 -30 35° 23.733' 120° 52.433'

Morro Strand Beach

Transect B

(MBBGS13-B)

B+12 (B1) 8/15/2013 15:53 +12 35° 23.333' 120° 51.947' B+6 (B2) 8/15/2013 15:55 +6 35° 23.333' 120° 51.97' B0 (B3) 8/15/2013 16:03 0 35° 23.33' 120° 52.008' B-6 (B4) 8/15/2013 15:35 -6 35° 23.317' 120° 52.117' B-12 (B5) 8/15/2013 15:30 -12 35° 23.333' 120° 52.167' B-18 (B6) 8/15/2013 15:25 -18 35° 23.317' 120° 52.217' B-24 (B7) 8/15/2013 15:20 -24 35° 23.317' 120° 52.267' B-30 (B8) 8/15/2013 15:10 -30 35° 23.317' 120° 52.317'

Morro Strand Beach

Transect C

(MBBGS13-C)

C+12 (C1) 8/15/2013 16:50 +12 35° 22.927' 120° 51.887' C+6 (C2) 8/15/2013 16:53 +6 35° 22.927' 120° 51.915' C0 (C3) 8/15/2013 16:55 0 35° 22.925' 120° 51.988' C-6 (C4) 8/15/2013 16:05 -6 35° 22.9' 120° 52.1' C-12 (C5) 8/15/2013 16:10 -12 35° 22.917' 120° 52.117' C-18 (C6) 8/15/2013 15:58 -18 35° 22.917' 120° 52.2' C-24 (C7) 8/15/2013 15:50 -24 35° 22.917' 120° 52.233' C-30 (C8) 8/15/2013 15:45 -30 35° 22.917' 120° 52.267'

Morro Strand Beach

Nearshore

(MBNGS13-B)

B1 8/15/2013 13:12 23* 35° 20.845' 120° 52.089' B2 8/15/2013 12:53 24.7* 35° 20.589' 120° 52.137' B3 8/15/2013 12:58 36.2* 35° 20.659' 120° 52.289' B4 8/15/2013 12:27 39.4* 35° 20.189' 120° 52.373' B5 8/15/2013 13:03 31.5* 35° 20.807' 120° 52.197' B6 8/15/2013 12:44 33.7* 35° 20.503 120° 52.278' B7 8/15/2013 12:36 27.4* 35° 20.373' 120° 52.193' B8 8/15/2013 12:32 30.5* 35° 20.296' 120° 52.262'

*Non-tidally adjusted water depth.

3.2.4 Summary of Morro Bay Harbor Testing and Evaluation Sequence

The testing and evaluation sequence used for the Morro Bay Harbor composite samples is described in detail in the next subsection and is outlined as follows:

1) Bulk sediment chemical analyses on each composite sample.

2) Grain size analyses on each primary core interval from the mudline to the overdredge depth plus from a select number of other core intervals.

3) Grain size compatibility analyses with the receiving beaches to determine if the Harbor sediments are physically compatible with the receiving areas.

4) Analytical results were evaluated using the sediment quality guidelines consisting of NOAA

Effects Range Low (ERL) and Effects Range Medium (ERM) values developed by Long, et al.

(1995) that correlate concentrations of selected contaminants with likelihood of adverse biological effects. Table 7 and the chemistry summary table list available ERL and ERM values.

Please note that ERLs and ERMs have not been developed for all analytes.

5) Analytical results were also evaluated using the USEPA’s RSL (Regional Screening Levels) and the State of California’s CHHSL (California Human Health Screening Levels) for potential effects to humans. Table 7 and the chemistry summary table list the available RSL and CHHSL values.

3.2.5 Physical Evaluation Guidelines

All geotechnical data gathered were used to do physical beach compatibility analyses between the dredged sediments and the receiving beaches.