Albion Bridge Geotechnical Investigation (EA 01 … Bridge Geotechnical Investigation (EA 01-40110;...

Albion Bridge Geotechnical Investigation (EA 01-40110; EFIS 01-0000-0154) Simple Revegetation Plan, December 2016

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1) Applicant and Contacts

a) Permit applicant, owner of revegetation site, and party with financial responsibility for completing revegetation work:

i) California Department of Transportation (Caltrans)

b) Permits requiring revegetation:

i) Coastal Development Permit for the California Coastal Commission

c) Contacts:

i) Revegetation Specialist: Kim Hayler, 1656 Union Street, Eureka CA 95501, (707) 441-2058

ii) Project Biologist: Hilary Sundeen, 1656 Union Street, Eureka CA 95501, (707) 441-3983

iii) Project Manager: Frank Demling, 1656 Union Street, Eureka CA 95501, (707) 445-6554

2) Geotechnical Investigation Activities and Dominant Species on Site Information about revegetation activities will be included in Section 4, below.

a) Geotechnical investigation activities and dominant species, per drill site:

Ten drill sites are proposed for this investigation. Some of the drill sites contain multiple bore holes (Appendix A, Figures 1 through 4). Bore holes would be approximately 5 to 6 inches in diameter. Grading is proposed for site access and equipment staging for some bore holes. Work proposed at each of the drill site locations is described below.

Drill Sites 1A, 1B, and 1C

Drill Sites 1A, 1B, and 1C would be accessed from the west side of State Route (SR) 1, south of the Albion River (Appendix A, Figures 3 and 4). They are located on the northeast facing slope, northwest of the south bound travel lane.

The sites are 10 feet wide and situated on ruderal vegetation intermixed with coyote brush scrub. Dominant species include sweet vernal grass (Anthoxanthum odoratum), rattlesnake grass (Briza maxima), velvet grass (Holcus lanatus), periwinkle (Vinca major), English ivy (Hedera helix), mustard (Brassica nigra), and cotoneaster (Cotoneaster sp.), with few native shrub species including coyote brush (Baccharis pilularis ssp. consanguinea), coffee berry (Frangula californica ssp. californica), and wax myrtle (Morella californica), with a small amount of coastal bramble (California blackberry, Rubus ursinus) at the south end of the project footprint, south of Drill Site 1C (see Appendix B, Photos 1, 2, 4, and 6).


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A self-leveling track mounted drill rig or rubber tired truck mounted drill rig will be used at this site. Boring depths are expected to be approximately 50 feet.

No revegetation is anticipated for Drill Sites 1A, 1B, and 1C and the adjacent project footprint because the vegetation would only be trimmed and not removed (see Appendix A, Figures 3 and 4). The presence of roots remaining in the soil would allow existing vegetation to resprout.

Drill Site 1

Drill site 1 would be accessed from the west side of SR 1, south of the Albion River (Appendix A, Figure 3). The metal beam guardrail that connects to the bridge would be removed while drilling is conducted. The site terrain ranges from flat to moderately steep. Extensive cut grading would be necessary to construct an access route and a sufficient level pad area. Anticipated pad dimensions are approximately 30 feet by 40 feet. An approximate 10 to 12 ft vertical cut into the hillside would be required.

Vegetation is sparse to moderately dense and consists of mainly ruderal vegetation similar to that found at Drill Sites 1A, 1B and 1C, with scattered coyote brush (see Appendix B, Photos 1 and 4). Vegetation removal and trimming would be required.

A rubber-tired truck mounted drill rig would be used at this site. Drill Site 1 would be used as the staging area for Drill Sites 2 and 3. Borings would be drilled to a depth of approximately 70 to 90 feet at this location.

Revegetation relative to Drill Site 1 is anticipated to occur within the area proposed for grading, which is within the black polygon in Figure 3 that is designated as Cut-fill limits.

Drill Site 2

Drill Site 2 would be accessed via drill site 1, west of SR 1, south of the Albion River because Drill Site 2 is on a relatively steep hillside below Drill Site 1; grading to provide direct vehicle access to the site is not feasible (Appendix A, Figure 3). Drill Site 1 would be used as the staging area for drill site 2.

Vegetation at Drill Site 2 is mainly ruderal, with coast silk tassel scrub (Garrya elliptica) observed just north of the drill site (see Appendix B, Photos 1 and 5).

To minimize ground disturbance and vegetation removal near the coast silk tassel scrub, a helicopter, crane, or winch would be used to get equipment and the drill rig to the site. A


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path between Drill Site 1 and 2 would be created by trimming vegetation. A temporary level steel platform would be constructed on which the drill rig would be placed. Due to the steep slopes at the site, the following is proposed for platform installation: on the inboard side, the platform would be stabilized by excavating a 30 foot (in length) notch in the hillslope to create a surface (approximately 4 inches deep), on which the platform would be placed. The outboard side of the platform would be supported at the corners using steel legs. Ground disturbance should be minimal. The amount of vegetation trimming would be dependent on the type and height of the vegetation where the platform is located. Borings would be drilled to a depth of approximately 100 to 120 feet at this location. Vegetation trimming with hand tools would be required at this location.

No revegetation is anticipated for Drill Site 2 because the vegetation would only be trimmed and not removed. The presence of roots remaining in the soil would allow existing vegetation to resprout.

Drill Site 3

To minimize ground disturbance and vegetation removal near the coast silk tassel and other native plants at Drill Site 3, a helicopter would be deployed to deliver the drill rig, steel platform, and supplies (Appendix A, Figure 3).

Vegetation at Drill Site 3 conforms to the coast silk tassel scrub natural community, with dominant species including coast silk tassel, thimbleberry (Rubus parviflorus), and sword fern (Polystichum munitum) (see Appendix B, Photo 5).

At this site, the work area would be approximately 30 feet x 40 feet, which includes the platform and any areas adjacent to the platform where foot travel is anticipated. Similarly to Drill Site 2, excavation of a notch in the hillslope would be necessary to create a surface for placement of the platform, legs would also be installed on the outboard side, as described for Drill Site 2. Borings would be drilled to a depth of approximately 125 feet at this location.

No revegetation is anticipated for Drill Site 3 because the vegetation would only be trimmed and not removed. The presence of roots remaining in the soil would allow existing vegetation to resprout.

Drill Site 4 – Removed from project; no revegetation needed.

Drill Site 5

Drill Site 5 is located near the base of a steep slope that descends from the edge of Highway 1 (Appendix A, Figure 2). The drill site would be approached along a paved access drive


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through the Albion Campground and Marina to the beginning of an unpaved access road approximately 100 feet east of the existing bridge and travelling west underneath the bridge, north of the north concrete tower, before turning north along the access road along the westerly edge of the existing bridge for approximately 200 feet to a 6 feet deep swale approximately 85 feet from Drill Site 5. Loose sand followed by possibly old sawdust waste underlies the entire route.

This area is dune habitat, with sparse vegetation consisting of the single dominant species, ice plant (Carpobrotus sp., invasive; see Appendix B, Photo 7). At the edge of the dunes, vegetation and elevation change as the dune habitat intercepts coastal bramble habitat, which includes California blackberry (Rubus ursinus) and thimbleberry as dominant species, and co-dominant species being sword fern, cotoneaster, and bracken fern (Pteridium aquilinum var. pubescens) (see Appendix B, Photos 2 and 3).

At this location (i.e., the last 85 feet from the site), the top of the dune ridge to the adjacent coastal bramble habitat forms a steep elevational gradient, approximately 6 foot deep. To access this site, an all-terrain rubber-tire or track-mounted drill rig would be needed. Additionally, mats may be required to facilitate transporting the drill rig to the site, where the steep slopes along the edge of the dune ridge intercept low-lying coastal bramble habitat, to create an accessible route for the drill rig. This may include moving sand temporarily to create a gentler slope for the drill rig to traverse to the drill site. The terrain would be restored once the drilling is completed. Support vehicles may be located near the north end of the campground. The estimated depth of the boring is 125 feet.

Revegetation relative to Drill Site 5 is anticipated to occur within the area proposed for grading, which is within the platform area in Figure 2.

Drill Site 6 and Drill Site 7

These drill sites are located on the generally steep slope above Drill Site 5 (Appendix A, Figure 2). The sites would be accessed from Highway 1. At drill site 6, a helicopter would be deployed to deliver the drill rig, steel platform and supplies. Existing vegetation, including approximately 260 eucalyptus trees, would have to be trimmed and/or cut prior to grading activities north of the Albion Bridge and west of the highway to accommodate vehicle access and staging. Underbrush would only be trimmed enough to allow installation of the steel platforms. The area to be graded is west of the highway and begins approximately 50 feet north of the Albion Bridge and extends approximately 275 feet north along the edge of the traveled way of the highway. The graded area will be sloped at +2% from the edge of travelled way until intersecting with the natural slope. At drill site 7, a crane situated in the


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newly graded area will deliver the steel platform and drill rig. The area to be graded is shown in Figure 2.

Vegetation at Drill Sites 6 and 7 includes a stand of eucalyptus (Eucalyptus globulus) and other sub-dominant species, including poison oak (Toxicodendron diversilobum), California blackberry, and Scotch broom (Cytisus scoparius) (see Appendix B, Photo 8).

Similarly to drill site 2, drill site 6 and drill site 7 will require excavation of a notch in the hillslope to create a surface for placement of the platform with legs installed on the outboard side. The estimated boring depth is 125 ft.

No revegetation is anticipated for Drill Sites 6 and 7 because existing underbrush would be trimmed sufficient to allow installation of the steel platforms. The presence of underbrush and eucalyptus tree roots remaining in the soil would allow existing vegetation to resprout.

Drill Site 8

Drill Site 8, which is also the abutment site, is located just west of the existing Highway 1 (Appendix A, Figure 2). Access to the site would also be off Highway 1.

Vegetation at the site includes a dense patch of eucalyptus with co-dominants that include poison oak, California blackberry and Scotch broom (see Appendix B, Photo 8).

The site would be graded to accommodate access for vehicles and staging. Much of the existing vegetation, including a number of eucalyptus trees, would be removed. A standard truck mounted drill rig would be utilized for borings that are located within the graded pad area. A steel platform and drill rig would be placed using a crane for the boring located slightly down slope of the graded pad area. The depth of the boring(s) would be approximately 70 to 90 feet.

Revegetation relative to Drill Site 8 is anticipated to occur within the area proposed for grading, which is within the black polygon in Figure 2 that is designated as Cut-fill limits.

3) Summary of Anticipated Impacts and Minimization Measures a) Summary of anticipated impacts:

i) The proposed geotechnical investigation work would temporarily affect approximately 0.44 acres of native coastal vegetation. This includes areas where vegetation would be trimmed for platform installation and areas where vegetation


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removal would be necessary after grading to provide site access and equipment staging. See Table 1 for a detailed summary of vegetation impacts, by community.

Table 1. Impacts to Vegetation Communities

Vegetation Type Vegetation Trimmed Vegetation Removed (Graded, Roots Affected)

Total Vegetation Affected (Trimmed & Removed)

Coastal Bramble (predominantly native)

597 sq.ft.(0.013 acre) 2,891 sq.ft. (0.066 acre) 3,488 sq.ft. (0.08 acre)

Coyote Brush Scrub (predominantly native)

9,282 sq.ft. (0.213 acre)

980 sq.ft. (0.022 acre) 10,262 sq.ft. (0.24 acre)

Coast Silk Tassel (predominantly native)

5,416 sq.ft. (0.12 acre) 0 5,416 sq.ft. (0.12 acre)

Eucalyptus Grove (predominantly non-native, invasive)

0 14,810 sq.ft. (0.34 acre) 14,810 sq.ft. (0.34 acre)

Total Acres 15,295 sf (0.35 acre) 18,681 sq.ft. (0.42 acre) 33,976 sq.ft. (0.78 acre)

Subtotal of Acres Dominated by Native Vegetation

15,295 sf (0.35 acre) 3,871 sq.ft. (0.08 acre) 19,166 sq.ft. (0.44 acre)

Subtotal of Acres Dominated by Non-native, Invasive Vegetation

0 14,810 sq.ft. (0.34 acre) 14,810 sq.ft. (0.34 acre)


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Table 2. Proposed Revegetation Activities, Based on Treatment of Existing Vegetation at Each Drill Site

Drill Site Proposed Revegetation Activities 1A, 1B, & 1C & surrounding graded areas

(Fig. 3 & 4) No revegetation proposed since no vegetation

removal (only vegetation trimming)

1 & surrounding graded area (Fig. 3 & 4)

Revegetation planned within the limits of the graded area & drill platform area; future reveg area is currently comprised of coyote

brush scrub and ruderal vegetation

2 (Fig. 3) No revegetation proposed since no vegetation removal (only vegetation trimming)


4 (removed from plan) Drill Site 4 and the surrounding Cut-Fill

Limits were removed from the plan, so no revegetation needed

5 (Fig. 2)

Revegetation planned within the limits of the platform area since vegetation removal

would be limited to the platform area for Drill Site 5. The Cut-fill Limits surrounding Drill Site 5, shown in Fig. 4, were removed from

the plan. Future reveg area is currently comprised mainly of coastal bramble (Rubus

parviflorus stand) vegetation.


7 (Fig. 2)

No revegetation proposed due to limited trimming of underbrush and trimming or

cutting of eucalyptus trees, and roots will be retained for at least the underbrush and some

eucalyptus trees

8 (Fig. 2)

Revegetation planned within the limits of the graded area & drill platform area; future

reveg area is currently comprised of a eucalyptus grove


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4) Revegetation Goal a) The revegetation goal is to ensure that the areas temporarily affected by grading for the

anticipated geotechnical drilling are on a trajectory toward becoming a self-sustaining native plant community that is dominated by regionally appropriate native plant species.

i) Currently, the proposed drill sites, grading areas, and revegetation areas are anticipated to be in the immediate vicinity of where the proposed alignment would be for the proposed bridge replacement.

ii) Caltrans discussed this with the California Coastal Commission, and the Coastal Commission requested that native plants still be installed in the geotechnical drilling areas, in case the bridge replacement project does not move forward as anticipated.

iii) If the bridge is replaced on the proposed alignment, the plants that were installed under this revegetation plan would be removed to allow construction, and the old alignment of the currently existing bridge would be revegetated with regionally appropriate, native plant species, unless another post-construction treatment is agreed upon by Caltrans, the Coastal Commission, and any other permitting agencies that provide a permit for construction work.

5) Summary of Initial Revegetation Activities a) Revegetation activities will include the following:

i) An enhanced permanent erosion control seed mix composed of regionally appropriate native species and a non-persistent annual grass will be hydroseeded at the end of construction in bare soil areas. The seed mix is considered enhanced by including a woody native plant component, which in this case is coyote brush. Coyote brush can withstand a variety of soil and hydrologic conditions and grows relatively quickly compared to other plants, so that it generally can withstand competition from invasive plants. It also is the dominant native species in the vicinity of vegetation removal, so it is the appropriate species to enhance the seed mix with. The erosion control seed mix is considered a specification that is managed by Construction and Landscape Architecture, and by Maintenance after construction is complete, so it is not part of the revegetation success criteria.

ii) Installation of container plants will occur approximately 1 year after construction, in fall or winter (i.e., between November and end of February), to allow the erosion control seed mix to establish and microsite conditions (e.g., hydrology, topography, etc.) to establish.

(1) Container plants will only be installed in areas that are safe to access for work crews.

(2) In areas where container plants cannot safely be installed and maintained, those areas are anticipated to have successful establishment of native vegetation via the erosion control seed mix, which will be enhanced with coyote brush seed.

(3) Species of container plants will be regionally appropriate; collected within as local a region as possible but restricted to coastal areas, preferably within


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Mendocino County; and will be comprised of species removed during grading activities and/or found within nearby areas that would have a good chance of surviving based on existing site conditions after grading. Coyote brush is the most likely species that would be used, but other local native species would be considered.

b) Parties involved with installation and establishment of container plants include the following:

i) Installation and plant establishment (i.e., watering, weeding, installation and maintenance of protective cages, etc.) would likely be conducted by the California Conservation Corps, with direction and oversight by Caltrans Revegetation Specialists.

6) Methods and Schedule of Site Maintenance for Container Plants after Initial Revegetation Activities a) Supplemental watering

i) Frequency of watering: every other week during the dry season, as directed by the Revegetation Specialist, for 2 years after initial planting

(1) The dry season is anticipated to occur between spring and fall/winter each calendar year. This is usually between April or May and October to December, depending on seasonal rainfall patterns.

(2) The CCC will commence watering as directed by the Revegetation Specialist.

(3) If a rainfall event occurs with more than ½ inch of rain while watering is being conducted, the Revegetation Specialist will determine whether to postpone supplemental watering and the duration to postpone. Watering will be postponed if the soil is saturated to the depth of plant roots.

ii) If there is a substantial drought and Caltrans is required to avoid watering, the plants may not be watered, or minimally watered. If watering is required to slow or stop, a remediation measure that may be implemented by the Revegetation Specialist would be to reduce biomass and increase available water and nutrients for installed plants by increasing the frequency of weeding events.

iii) Amount of watering: Each plant will receive 2 gallons of water per visit, using municipal water sources.

b) Other site maintenance activities

i) Duration of site maintenance: 3 years after installation of container plants, pending concurrence from the Coastal Commission.

ii) Anticipated activities: Weeding, mulching of installed and volunteer plants, fixing or removal of cages, thinning of stump sprouts, installation of replacement plants, and any other activities determined necessary by the Revegetation Specialist or Biologist to assist with establishment of native vegetation in the planting area.


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(1) Weeding will focus on hand-clearing invasive non-native vegetation within a 3 to 4 ft radius around installed plants and desirable native volunteer plants. No chemical control will be used. Weeding will also target invasive non-native species within the flat planting area.

(a) Some invasive species that currently exist on site will regenerate on site and will be infeasible to eradicate; however, they will be controlled in the planting area to the extent feasible during the three-year maintenance period to ensure that installed plants survive and establish. Once the native plants are established, they will survive competition with these invasives.

(b) Newly introduced invasive plant species will be documented for monitoring reports and removed from the flat planting area.

(2) Re-seeding with regionally appropriate native species and covering with organic rice straw or other weed free straw is often necessary after large patches are weeded. Alternatively, a thick layer of mulch may be used to suppress growth by invasive species in problematic areas.

(3) Mulching: Installed plants will retain an approximately 3 to 4 inch layer of wood chip mulch; re-mulching will likely be necessary during the three-year maintenance period.

(4) Replanting, if determined necessary after monitoring, will be conducted using regionally appropriate natives, and watered and maintained as stated above.

iii) Annual site inspection to determine maintenance needs: The Revegetation Specialist or Biologist will inspect the site at least once annually to determine maintenance needs.

7) Monitoring Methods and Performance and Success Criteria a) Monitoring methods and schedule will include the following:

i) Photo points: At least one photo point will be established in each revegetation area by the time of plant installation, to show the majority of plantings. The photo point will provide a visual indication of survival and establishment of native plants.

ii) Counts of native plants. Installed, resprouting (i.e., stump-sprouting), and volunteer native plants that are alive during monitoring will be counted, by species. Establishment of volunteer native species may be included in the total plant count, since volunteers indicate that revegetation is successfully occurring and that a site is on a trajectory toward being self-sustaining.

(1) Determination to replant: If survival of installed plants is not meeting the Year 1 performance criterion, resprouting is not occurring adequately, and/or few native volunteer plants are establishing, the site will receive additional planting, as determined by the Revegetation Specialist or Biologist.

iii) Schedule: photo points and survival counts will occur annually between June 1 and November 30 for 3 years after initial planting, starting as early as the first June after


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plant installation. Since plant installation will occur by February, monitoring between June and November will allow a sufficient duration of time to indicate whether plants are surviving and establishing during the 1st growing season.

b) Performance and success criteria for survival counts:

i) Year 1: At least 90% of installed container plants and/or volunteer native plants will be alive in monitoring year 1. Volunteer native plants may count as replacements for installed plants or add to the plant count, so that there may be more than the original number of installed plants if most or all plants survive and multiple volunteer native plants emerge.

ii) Year 2: At least 80% of installed container plants and/or volunteer native plants will be alive in monitoring year 2. Volunteer native plants may count as replacements for installed plants or add to the plant count, so that there may be more than the original number of installed plants if most or all plants survive and multiple volunteer native plants emerge.

iii) Year 3: At least 70% of installed container plants and/or volunteer native plants will be alive in monitoring year 3. Volunteer native plants may count as replacements for installed plants or add to the plant count, so that there may be more than the original number of installed plants if most or all plants survive and multiple volunteer native plants emerge.

c) Brief monitoring reports will be developed each year.

i) Reports for monitoring years 1 and 3 will be submitted to the California Coastal Commission.

ii) The report for year 2 will be kept in the project file.

8) Remedial measures a) If performance/success criteria are not met, the Revegetation Specialist and/or Biologist

will assess potential reasons for a criterion not being met and develop remedial measures to correct issues. Caltrans will contact the Coastal Commission to discuss the success criteria issues and develop a plan to resolve the issues if the planting area is not on a trajectory toward meeting the 3rd year success criterion.

b) Any remedial measures that are implemented will be discussed in monitoring reports.


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Appendices

• Appendix A. o Maps

• Appendix B. o Representative photographs of habitat types present within the project limits

Appendix A

Maps

Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS,USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GISUser Community

Figure 1Project Area

0 0.045 0.090.0225 Miles

µ

Legenddunesvegetation removedvetetation trimmedruderal vegetationeucalyptus grovewax myrtle scrubcoyote brush scrubcoastal brambleCoastal silk tassel scrubstudy area

Drill Site 7

Drill Site 8

Drill Site 5

Drill Site 6


Figure 2 (DS 5, 6, 7 & 8)Vegetation Communities observed in the

Project Footprint and 100-foot buffer

0 0.015 0.030.0075 Miles

µ

LegendCut-fill limitsDrill Siteplatformruderal vegetationcoyote brush scrubcoastal brambleduneseucyliptus grove

Access Road

Drill Site 2

Drill Site 3

Drill Site 1

Drill Site 1A


Figure 3 (DS 1, 2, 3 & 4)Vegetation Communities observed in the


0 0.015 0.030.0075 Miles

µ

LegendCut-fill limitsDrill SiteProject FootprintplatformESHA Study AreaMHHWAlbion River Estuaryruderal vegetationcoyote brush scrubcoastal bramblewax myrtle scrubdunes

Drill Site 1B

Drill Site 1C

Drill Site 1A

Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics,CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN,IGP, swisstopo, and the GIS User Community

Figure 4 (DS 1A, 1B & 1C)Vegetation Communities observed in the


0 0.015 0.030.0075 Miles

µ

LegendProject FootprintCut-fill limitsDrill SiteESHA Study Arearuderal vegetationcoyote brush scrubcoastal bramble

Appendix B:

Representative photographs of habitat types present within the project limits

Photo 1: Representative photo of ruderal vegetation (non-native annual grasslands).

Photo 2: Representative photo of coastal bramble.

Photo 3: Representative photo of coastal bramble.

Photo 4: Representative photo of coyote brush scrub alliance.

Photo 5: Representative photo of coast silk tassel scrub.

Photo 6: Representative photo of wax myrtle scrub

Photo 7: Representative photo of ice plant mats.

Photo 8: Representative photo of eucalyptus grove.

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