Harbor  District Oyster Point Marina/Park Pillar Point Harbor SMCHD Home


Pillar Point Harbor
DREDGING AT PILLAR POINT HARBOR
   



ARMY CORPS OF ENGINEERS PUBLIC MEETING ON SURFERS BEACH PROJECT, NOVEMBER 8, 2013, PRINCETON...>
Click here to view

DREDGING NEEDS, EROSION CONTROL, AND DREDGED MATERIAL BENEFICIAL REUSE AND DISPOSAL STRATEGY AT PILLAR POINT HARBOR click here for updated report

DREDGING AT PILLAR POINT HARBOR

The San Mateo County Harbor District is providing this new web page in response to considerable recent public interest in situations at Pillar Point Harbor that involve or may involve dredging: clearing sediment to aid navigation, and placing dredged sediment for beneficial use. This page is designed to keep you informed about the Harbor District's activities that do, will, or may involve dredging and placement of dredged material at Pillar Point Harbor, and to provide an opportunity for questions and comments (see area map below)

click here to see larger map.
Click here to see additional map for dredging.
It contains information on current dredging-related projects and related documents of interest. It will be kept current. Schedules of public meetings and other gatherings of interest regarding dredging projects will be posted.

Current Dredging and Dredging-Related Projects

    Pillar Point (PPH) Boat Launch Ramp Maintenance Dredging (Harbor District).

    UPDATE: ON JUNE 14TH, 2013, THE COASTAL COMMISSION APPROVED THE HARBOR DISTRICT'S APPLICATION TO DREDGE THE PILLAR POINT BOAT LAUNCH RAMP AND PLACE 3,500 CUBIC YARDS OF MATERIAL ON THE NEARBY PERCHED BEACH SITE, ITSELF COMPRISED OF DREDGED MATERIAL FROM PREVIOUS DREDGING EPISODES.

    Background: The Harbor District's boat launch ramp at PPH, built around 1992, periodically requires maintenance dredging to keep its three ramps open for use. Emergency dredging was last done in 1999 and 2006 to remove siltation caused by severe storm activity leading to runoff from Deer Creek in EI Granada. The dredged material was placed on the nearby perched beach, a dredged material disposal site that was created in the 1980's by the original dredging to create Pillar Point Inner Harbor's boat basins.

    Once again, the ramp needs to be dredged. The District began the process of applying for the necessary permits and approvals at the end of 201l. The Army Corps permit, Regional Water Quality Control Board certification, and the State Lands Commission lease have been received . The Coastal Commission permit approval is expected in April. Regulatory requirements for additional testing of the approximately 5,600 cu. yds. of material to be dredged and conduct of an eelgrass study considerably lengthened permit approval time.

    The perched beach disposal site will be used for this maintenance dredging episode as in the past. The actual disposal location will not eliminate use of the beach for commercial and private kayak use and other public water access. Permit requirements call for the sediment to be contained within a berm on the upland side of the beach. The actual amount to be dredged is no more than in either ofthe two previous episodes in 1999 and 2006.

    Urgency factor: Because over half of the launch ramp is now silted up, no alternative disposal site to the perched beach site (which is very close to the launch ramp and hence most cost-effective) is or will be available in time to accommodate this dredging episode before the start of the salmon fishing season in early April.

    Surfers Beach Erosion Control and Beach Restoration Project (U. S. Army Corps of Engineers). Background: The Pillar Point outer breakwater was built and is maintained by the U. S. Army Corps of Engineers. After World War 2, Coastside and other citizens petitioned Congress to provide a harbor of refuge for the fishing fleet. In 1947, the Army Corps of Engineers recommended constructing the breakwater. It was built between 1959 and 1961, with an addition to the west arm in 1966-67.

    Erosion of Surfers Beach at an increasing rate has occurred since the east arm of the federal breakwater was built (See Section 216 Initial Appraisal below). This is a longstanding concern of beach users, surfers, local citizens, the Harbor District, the County, and Caltrans, especially because of concerns regarding protection of Highway 1. The District and harbor users have also been concerned with the loss of vessel anchorage area within the outer harbor as a result of sediment trapped behind the east arm of the outer breakwater. (see Bathymetry Study & Outer Harbor Channel Design following)

    Pillar Point Harbor
    Bathymetry Study & Outer Harbor Channel Design

    Using these delta plots, we then identified 9 zones of scour and accretion for further examination (Work Product 3, see Figure 2). Zone boundaries were chosen to create areas having similar rates of scour or accretion and to also isolate the inner breakwater area from the outer areas of the harbor. Results and Conclusions As can be seen from Table 1 (Work Product 4), between 1994 and 2006 the entire harbor experienced 37,127 cubic yards (CY) of scour and 15 1,787 CY of accretion, resulting in a net accretion value of 114,660 CY. Each individual zone experienced scour and accretion, exemplifying the hydrological and sediment transport dynamics of the harbor.
    Table 1
    Scour/Accretion Quantity Calculations
    Since we are studying zones of differing sizes, it is helpful to examine the normalized rates of change in the last 2 columns of Table 1 (i.e., average depth of scourlaccretion over the 12-year period and on a per-year basis). This comparison uses net scour or accretion quantities coupled with the total area of a specific zone in order to give a relative assessment of scour and accretion rates. For instance, even though Zone 3 has a higher net accretion volume (33,874 CY) than Zone 2 (31,098 CY), Zone 2 covers a much smaller area. By taking the zones' areas into consideration, it can be noted that Zone 3 has less change in elevation (+0.32 feet) when compared to that of Zone 2 (+0.59 feet). Furthermore, the largest zone (Zone 5) has the lowest net elevation change (+0.02 feet). This example is striking when compared to Zone 4, which includes a much smaller area, but has experienced a net elevation change of +2.72 feet. click here to see zone map.
    GSA Gahagan & Bryant Associates,
    Inci Page 4

    In 2007, the Harbor District asked the Army Corps of Engineers to investigate the erosion along the approximately one mile of shoreline from the foot of the breakwater to the vicinity of Medio Creek, in Miramar. At this time the District had been approached by some local surfers who expressed concerns about loss of beach. The Corps completed a Section 216 Initial Appraisal in July 2009 (see Section 216 Initial Appraisal below), which concluded that there is a federal interest in addressing shoreline issues arising from the breakwater construction.

    SECTION 216 INITIAL APPRAISAL
    The purpose of this Initial Appraisal is to review the existing United States Army Corps of Engineers (Corps) project Pillar Point Harbor (authorized in 1948 with initial breakwater construction from 1959 to 1961) to determine whether it is appropriate for the Corps to participate in the resolution of documented shoreline erosion and structural damage along the northern open-ocean shoreline of Half Moon Bay. The non-federal sponsor has stated that the negative shoreline impacts in that area can be attributed to the original Corps project.
    The area of concern (proposed project area) starts at the root of the East Breakwater and extends southward a distance of approximately one mile to Arroyo de en Medio, which is near the southern end of Miramar Beach. Because of its relative stability since breakwater construction, the Half Moon Bay shoreline between Arroyo de en Medio and Miramontes Point is not included in this Initial Appraisal.

    Federal interest will be based on two factors:
    • The extent of the post-construction shoreline change beyond the natural change that would have been expected without the Pillar Point Harbor project
    • The economic viability of a potential project to mitigate for such physical changes.

    TABLE 2: Construction at Pillar Point Harbor and Shoreline Condition
    Date Event Beach Condition
    Prior to 1959 Natural Conditions Minimal erosion with broad sandy beach
    1959 to 1965 Two Outer Breakwaters Built Increase in erosion with a loss of approximately 75,000 yd3 per year (USACE, 1971)
    Prior to 1971 500 ft revetment built starting at root of East Breakwater Stopped local cliff retreat (USACE, 1971)
    1982 Two Inner Breakwaters Built No impact on erosion south of the East Breakwater
    1959 to present Various remedial actions induding rubble-mound revetments Erosion rates increased from 0.25 ft per year to as much as 7 ft per year (Griggs et a!., 2005) where the bluff is exposed.
    Inside the harbor, sediment has accumulated adjacent to the East Breakwater creating dunes and a beach. Between that beach and the inner breakwater, sufficient sand has accumulated to elicit concern from the Harbor District about restricted small-boat access to the inner harbor via the east entrance. That sand probably comes from erosion of the Princeton shoreline and material coming down Denniston Creek and Deer Creek. It is also possible that some of the sand in the delta comes from the south or through the harbor entrance during large storms. Pre-breakwater, that sand would have moved alongshore to the south.

    The District and the Corps signed a Feasibility Cost Share Agreement (FCSA) in September 2010 for a project under Continuing Authorities Program (CAP) Section 111 Mitigation of Damages Caused by a Federal Navigation Project. The Corps is the Lead Agency for the project; the District is the Local Sponsor. This FCSA provides for a 50:50 cost share between the Corps and District for the pre-design phase of the project.

    The project's two-to-three year feasibility phase, now in progress, is focused on identifying the feasibility of a possible project that would demonstrate solution(s) to the beach erosion problem that will have no or minimal environmental impacts on marine sanctuary and other natural resources. This could potentially include transferring sediment trapped behind the breakwater onto Surfers Beach according to a permitted project design.

    To facilitate public and technical input to the Corps during this phase, the Harbor District organized a Working Group consisting of concerned federal and state agencies, representatives from elected Representatives' offices, technical resource persons, and community residents. The Group has been convened and will continue to function during the Corps project. The Corps has convened public meetings, with the District's assistance and coordination. The District notices these meetings on its website and at the PPH office.

    The Army Corps has finished its analysis of existing site conditions and is now examining potential project benefits, including economic and environmental considerations, going forward from the start of this project.

    Meanwhile, District staff has met with County Parks Division staff regarding their public safety and beach access improvement project at EI Granada above Surfer's Beach. An inter-agency meeting was recently held involving the Army Corps, County Parks and Public Works, Coastal Commission, Caltrans, the Gulf of the Farallones National Marine Sanctuary, the Harbor District, and staff from elected Representatives' offices to exchange information, establish coordination links, and identify next steps for action.

    Key Issues: Some community members have expressed concern at the apparent slow pace of the Corps' project. Questions also have been raised as to why the Harbor District cannot apply for a permit and deposit sediment on Surfers Beach from its launch ramp dredging or from the buildup inside the breakwater. Regarding the first - timing, the Corps' project development process calls for a Feasibility Planning Phase of 2-3 years duration. (The Corps/District Agreement was executed in September 2010.) Some may be unfamiliar with what seems a lengthy period needed for planning.

    Regarding the second, any agency seeking permission to dredge and dispose of the material needs permits, certifications, and approvals from several federal and state agencies. Additionally, for Surfers Beach, the Monterey Bay National Marine Sanctuary and the Gulf of the Farallones National Marine Sanctuary (which administers sanctuary waters for Monterey Bay in the Half Moon Bay [and Surfers Beach] area) follow a national sanctuary policy that prohibits artificial placement of any material in sanctuary waters. An agency, be it the Army Corps or the Harbor District, could seek sanctuary approval to deposit sediment on Surfers Beach, but they would have to demonstrate that such action would have no negative impact on sanctuary resources, species and habitats. And then, the sanctuaries would have to find a way to grant an exception to the national policy prohibiting artificial placement. Moreover, the applicant agency would still need all the other permits and approvals.

    An essential part of the Army Corps' Surfers Beach project, for which the District is the local sponsor, is precisely to develop the information necessary for the sanctuaries, and other permit agencies, to reach a positive conclusion about the project's impacts.

    Regional sediment management planning is beginning for the Santa Cruz Littoral Cell, which goes from the northern end of Monterey Bay north to Pedro Point in Pacifica, and which includes the Half Moon Bay area. This effort may provide valuable information regarding possible project alternatives for beneficial use of sand at Surfers Beach that could be favorably viewed by the marine sanctuaries.

Future Dredging Project Possibilities
    Inner Harbor Maintenance Dredging: Several spots within the inner breakwater are showing signs of silting up and will need to be dredged soon so boating operations are not obstructed. The Harbor District plans to program this maintenance dredging activity into its forthcoming budget process. A sediment disposal site for this episode will need to be selected and approved.

    Princeton Shoreline: Since the construction of the federal breakwater at Pillar Point in 1959-1961, the Princeton Shoreline has experienced beach erosion caused by wind waves across the outer harbor with no source of replenishment. The Army Corps could determine a federal interest in working with a local sponsor to address this problem, as they did for Surfers Beach. San Mateo County is starting a comprehensive Princeton planning process with shoreline erosion as an item of specific concern. This might lead to constructive action, possibly using dredged harbor sediment for beach replenishment. Work by the County's consultant is supposed to begin in March.

    The Harbor District, operating strictly in a limited facilitating role and at the request of the Coastal Commission, obtained a Coastal Conservancy grant and had a preliminary engineering assessment done in 2001 that identified three possible approaches to shoreline protection based on six individual concepts, including a sand replenishment option (see attachment Northern Half Moon Bay Shoreline Improvement Project). At that time the District was in contact with the Princeton Citizens Advisory Committee and the County Park and Recreation Division. This preliminary engineering work could be of value to the County's planning effort.