Variation of Beach Morphology along the Saco Bay Littoral Cell

Recommendations

The current study has identified certain morphologic trends along the Saco Bay shoreline. Net erosion and accretion, and subsequent subaerial-to-intertidal beach volumetric changes were determined at 100-foot beach profile transects along the shoreline. Certain beach features, such as maximum dune elevation, are important safety features in protecting developed shorelines from storm events. As a result, shorefront communities may find portions of this document useful for planning purposes. The following recommendations are solely based on trends seen within the current study. It is suggested that communities use this document for preliminary guidance only, and contact appropriate consultants in order to receive additional guidance regarding shoreline studies and subsequent planning. It is also recommended that communities along Saco Bay work to develop federally approved hazard mitigation plans in order to deal with both short and long-term coastal hazards. Recommendations include the following:

Regional Sediment Management

Communities within the Saco Bay littoral cell should consider implementation of a regional sediment management plan. Sediment, in general, originates from and is confined within the bay. Sand "recycling" may therefore be an extremely effective measure in dealing with areas of erosion and accretion. Previous authors (e.g., Kelley and others, 1995) have proposed such a sediment management plan. Since there are two federal navigation projects located at both ends of the bay (one at the source, the Saco River; and one at Scarborough River), communities should look to couple their efforts with federal dredging projects (under Corps Operations and Management funding) for sediment backpassing from northern, highly accretive beaches, to southern erosive beaches. Saco Bay seems to be a perfect location to implement the Corps' new Regional Sediment Management (RSM) program, and funding may be available through this program (Rosati and others, 2001).

Elevating Above Base Flood Elevations

Communities exhibiting maximum profile elevations (e.g., dune or seawall crests) below established FEMA base flood elevations should take mitigation actions to create more protective frontal dunes, or in the case of existing rocky shoreline outcrops, elevating existing structures above the base flood elevation (BFE). This should be applicable even to those areas that have a relatively wide landward distance to structure. Sections of shoreline that should consider this recommendation are:

Region 1, Hills Beach: intermittently from 2,400-3,900 ft, but especially just north of Surf Avenue, near 2,800 ft; and from near the thinnest part of the island (near 4,500 ft) northwest to near Pleasant Avenue (5,100 ft), see Figure 33.
Region 2, Camp Ellis Beach: in the vicinity of Riverside Avenue (8,300 ft), see Figure 34.
Region 3, Old Orchard Beach: possibly near Old Orchard Street (26,700 ft); Surfside: several pockets stretching from near Grandview Avenue (33,600 ft) northeast to just north of Parcher Avenue (34,000 ft), see Figures 36 and 37.
Region 4: no areas apply.

Widening Dry Beach Widths

Communities exhibiting dry beach widths less than 25 ft should consider some form of beach restoration (especially those stretches of shoreline that have dry beach widths of less than 25 ft and total landward distances of less than 100 ft). Sections of shoreline that should consider this recommendation are:

Region 1, Hills Beach: from 0 to 1,900 ft, and from near 2,500-4,300 ft, see Figure 33.
Region 2, Camp Ellis Beach: from the northern jetty to 9,700 ft (near Eagle Ave.), see Figure 34.
Region 3: no areas apply.
Region 4: unknown, although no areas appear to apply.

Increasing Total Landward Widths

Communities with total landward widths from HWL to the seaward edge of the first habitable structure of approximately 100 ft or less should consider some form of beach and/or dune restoration in order to provide a larger natural buffer between dunes or seawalls and habitable structures. This recommendation does not apply to habitable structures fronted by exposed rocky shorelines (e.g., southern Hills Beach). Sections of shoreline that should consider this recommendation are:

Region 1, Hills Beach: near the southern end of Hills Beach Road (400-900 ft); in the central-northern section of the beach (2,400-4,200 ft), see Figure 33.
Region 2, Camp Ellis Beach: from Bay Avenue north to near Fairhaven Avenue (7,700-9,700 ft); Bay View: in the vicinity of the condominiums just south of Bay View Avenue (14,800-14,900 ft); Kinney Shores: near Goosefare Brook (17,700-18,700 ft), see Figures 34 and 35.
Region 3, Ocean Park: immediately adjacent to the north side of Goosefare Brook (19,700-19,900 ft); Old Orchard Beach through Surfside: intermittently from 28,100-29,700 ft, see Figures 36 and 37.
Region 4: no areas appear to apply.

Plan for 100-yr Erosion

Communities with projected 100-year shorelines showing areas of erosion that may adversely affect habitable structures should consider advance beach restoration and/or structure relocation or acquisition measures. Sections of shoreline that should consider this recommendation are:

Region 1, Hills Beach: in the vicinity just north of Surf Avenue (near 2,000-2,200 ft), see Figure 33.
Region 2, Camp Ellis Beach to Ferry Beach: from Bay Avenue north to Island View Avenue (from 7,700-10,200 ft); Ferry Beach: from Island View Avenue to seaward of Long Pond (10,200-12,900 ft), although no structures appear to be impacted; Kinney Shores: from near Pinewood Avenue north to Goosefare Brook (17,700-18,700 ft), see Figures 34 and 35.
Region 3, Ocean Park: possibly from just south of Sandpiper Avenue to near Colby Avenue (20,000-20,500 ft); Surfside: from near Grandview Avenue northeast to near Parcher Avenue, in the vicinity of the former Little River Inlet (32,000-32,500 ft), see Figures 36 and 37.
Region 4, Western Beach: adjacent to the Scarborough River jetty, near Tee #2 (44,700 ft), and near the practice green (46,300 ft), although no structures appear to be impacted, see Figure 38.

Plan for 100-yr Accretion

Communities with projected 100-year shorelines showing areas of substantial potential accretion must plan accordingly. As shorelines build seaward, community planners should be prepared to address ownership, access, zoning, and development issues that may result. Sections of shoreline that should consider this recommendation are:

Region 1, Hills Beach: from near the roundabout of Hills Beach Road northwest to near Surf Avenue (800-2,000 ft); and from near the thinnest portion of the island northwest to the southern Saco River jetty (4,200-6,000 ft), see Figure 33.
Region 2: no areas appear to apply.
Region 3, Ocean Park to Old Orchard Beach: from the vicinity of Tunis Avenue northeast to Fernald Avenue (21,900-25,500 ft); Grand Beach to Pine Point: from Little River Road northeast into Pine Point (35,700-42,300 ft), see Figures 36 and 37.
Region 4, Western Beach: the majority of the beach, aside from areas noted with potential erosion, see Figure 38.

Consider Shoreline Structure Maintenance or Removal

Communities with existing seawalls should evaluate the effectiveness of the structures in protecting development, the future rehabilitation/renovation expenses associated with structure maintenance, and investigate additional shoreline protection options. Sections of shoreline that should consider this recommendation are:

Region 1, Hills Beach: central portion of the beach, from 2,900-4,200 ft, see Figure 33.
Region 2, Camp Ellis Beach: from Bay Avenue north to Fairhaven Avenue (7,700-9,700 ft); Kinney Shores: from Outlook Avenue to Goosefare Brook (17,100-18,700 ft), see Figures 34 and 35.
Region 3, Old Orchard Beach: from Fernald Avenue northeast to near Linwood Street (25,500-27,900 ft), see Figure 36.
Region 4: no areas apply.

Proximity to Tidal Inlets

Communities with areas situated within or directly adjacent to the limits of a tidal inlet should pay close attention to historical and existing erosion trends, as such areas are generally erosive 'hotspots,' are generally lower in elevation, and are subsequently prone to periodic overwash. Sections of shoreline that should consider this recommendation are:

Region 1, Hills Beach: in the vicinity of the thinnest portion of the island, from 3,500-4,200 ft (abandoned oxbows and meandering tidal channel in back marsh), see Figure 33.
Region 2, Camp Ellis Beach: adjacent to the north jetty, from Bay Avenue to Main Avenue, 8,000-8,400 ft (marsh landward of Camp Ellis pier); Kinney Shores: from near Pinewood Avenue north to Goosefare Brook, 17,700-18,700 ft (abandoned, meandering channels of Goosefare Brook), see Figures 34 and 35.
Region 3, Surfside: from near Grandview Avenue northeast to near Parcher Avenue, 32,000-32,500 ft (in the vicinity of the abandoned channel(s) of Little River Inlet); Pine Point: adjacent to the Scarborough River, see Figure 37.
Region 4, Western Beach: adjacent to Scarborough River jetty southeast towards Prouts Neck, associated with abandoned channel (43,700-44,500 ft), see Figure 38.

Section 111 Plan Alternatives: Coastal Engineering and Mitigation at Camp Ellis

Based on the analysis in this report, erosion problems along the Saco Bay shoreline appear to be localized to Camp Ellis Beach and portions of Ferry Beach, and also appear to be a direct result of the negative influence of the Saco River jetties. Upon jetty construction, the downdrift beach first accreted due to landward ebb-delta shoal migration; however, once this sediment moved landward, it was slowly eroded and reworked northward. With the jetties in place, no new sediment was available to adjoining beaches, and they have faced continual erosion since approximately 1900.

A 1992 Section 111 study by the Corps presented several alternatives to deal with the erosion problems along the southernmost 2,500-foot stretch of Camp Ellis and Ferry Beaches. Original alternatives included 6 Plans:

beach nourishment;
revetment/seawall;
roughening jetty face and beach nourishment;
larger spur jetty;
larger spur jetty with beach nourishment; and
acquisition and demolition of structures within a projected 50-year erosion zone.

Subsequent cost-to-benefit analyses by the Corps determined that none of the options were economically justified at the time (USACE, 1992).

In 1995, the Corps' Waterways Experiment Station (WES) laboratory completed a model study of the Camp Ellis Beach erosion problems. WES analyzed existing conditions in addition to some of the alternatives (and several variations) presented by the 1992 study. Conclusions indicated that any beach-fill plan would only be a temporary solution that would require periodic nourishment, and that an approximate 3,000 linear foot spur jetty was most effective in significantly reducing wave heights and beach erosion along Camp Ellis Beach.

In 2001, the Corps updated its 1992 Section 111 study at the request of the City of Saco and Congressman Thomas Allen. This study reviewed the original plans proposed in the 1992 study and found that Plan C, which included roughening approximately 1,000 linear ft of the shoreward most portion of the jetty and placement of approximately 275,000 cubic yards of beach-fill, was economically justifiable (USACE, 2001).

To date, the Saco Bay Implementation Team has been meeting to determine the most physically effective alternatives to alleviate the high erosion rates seen at Camp Ellis, while attempting to minimize impacts to the rest of the Saco Bay littoral system. At the time of the publication of this document, the Corps is in the process of collecting real-time wave and current data for the purposes of groundtruthing a nearshore numerical wave model. This model will be utilized to analyze several different structural alterations to the northern federal jetty, including several spur jetty configurations, roughening the innermost 1,000 feet of the existing jetty, removing the seaward end of the jetty, and several T-groin configurations along the shoreline. Results of the numerical model may indicate the most effective alternative for reducing storm wave heights, and subsequent erosion, along Camp Ellis beaches.

A successful overall long-term mitigation solution must not only take actions to substantially decrease existing erosion rates along Camp Ellis Beach (which range from 1-3 ft/year based on the data utilized in this report), but must also take into account the regular addition of sediment to the currently starved system. However, without a successful decrease in the existing erosion rate, any addition of beach nourishment material will only be a short-term, temporary solution. In order to help deal with this issue, it is recommended that the community of Camp Ellis address long-term coastal hazard issues through the development of a hazard mitigation plan, which would improve the community's resistance to flooding and coastal damage from storm events.

Contents Introduction Historical Background Methods Results Discussion Recommendations Conclusions Additional Study and Research References Appendix A

Last updated on January 10, 2006.