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Clocksin Property Revegetation and Restoration Plan

Duane Clocksin 17721 14th Ave NW Shoreline, WA 98177

October, 2015

6310 NE 74th St, Suite 201E Seattle, WA 98115

EarthCorps © 2015 All rights reserved

6310 NE 74th Street, Suite 201E, Seattle, WA 98115 phone 206.322.9296

1. Introduction This Plan addresses the revegetation of a section of a slope present on the western portion of the property behind the residence located at 17721 14th Ave NW. During a field survey conducted on July 29, 2015, a portion of the slope was examined in the vicinity of eight pruned trees – seven resprouted bigleaf maple (Acer macrophyllum) coppices and one non-native sweet cherry (Prunus avium) tree (Figure 1 – Site Plan). All trees that were affected consisted of previously cut tree boles that had extensively re-sprouted. During the course of this disturbance, other vegetation was likewise impacted in the area. Most of the impacted vegetation was non-native invasive Himalayan blackberry (Rubus bifrons) and non-native invasive hybrid Japanese knotweed (Polygonum ×bohemicum), with a small amount of native salmonberry (Rubus spectabilis) and western sword fern (Polystichum munitum) also affected. Most of the impacted vegetation occurred on the perimeter of the disturbed areas as the canopy from the pruned maples appeared to be limiting other plant establishment. The undisturbed vegetation below and to the north of the affected area is comprised primarily of Himalayan blackberry with lesser amounts of salmonberry, willow (Salix spp.), and other species. See attached Site Plan for the locations of affected trees in the area and proposed restoration vicinity. The entire area of the disturbance is approximately 25 feet wide by 75 feet long down slope (see Site Plan), much of which is covered by downed debris from the pruning. The upper portion of the disturbed area is located on a relatively steep slope that is currently devoid of vegetation or debris, approximately 20 feet wide and extending 30 feet down slope. The property owner has installed coir fabric and coir erosion control logs on the face of this steep slope. In addition to the blackberry clearing, a section of hybrid Japanese knotweed was cut back in a less steep portion of the hillside to the north. At the time of the assessment, these plants had aggressively re-sprouted and showed no signs of long term damage. This Plan proposes a long-term strategy to revegetate the entire disturbed area with native plants to increase habitat structure and to stabilize the slope against potential erosion.

2. Restoration Plan and Site Preparation Before native plants are installed, it will first be necessary to remove any existing non-native invasive plant species within the proposed restoration area in the direct vicinity of the affected trees (see Site Plan). These species include Himalayan blackberry and hybrid Japanese knotweed. Most of the Japanese knotweed is located further to the north on the slope and was only noted on the northeast edge of the proposed restoration area. However, this species can spread aggressively and will need to be controlled and kept from encroaching into the restoration site. It is recommended that short term measures be taken to keep this species from spreading until a full eradication plan can be implemented on the property. These measures could include hand digging new sprouts in the restoration area or spot treatments with an approved herbicide. See King County Noxious Weeds for more information: Himalayan blackberry is only present within the proposed area in a limited distribution. These plants should be controlled before planting to reduce competition and allow for more effective

6310 NE 74th Street, Suite 201E, Seattle, WA 98115 phone 206.322.9296

maintenance of the site. Manual removal can be effective if the root ball is dug up, although care needs to be taken to minimize soil disturbance. On steep slopes, blackberry canes can be cut and wiped with an approved herbicide (such as Roundup), which can be effective at killing the plant with minimal disturbance to the soil. This method can also be effective to treat blackberry that is growing through the installed erosion control fabric. See King County Noxious Weeds for more information: In addition, some of the debris form the pruning may need to be cut and moved to facilitate invasive species removal and planting efforts. It is recommended that this material be stacked to provide habitat enhancing brush piles and allowed to decompose on-site.

3. Planting Plan The approximate area addressed in this Plan to be revegetated is approximately 2,164 square feet (see Site Plan). A portion of the steeper section of the upper slope has been covered with biodegradable coir erosion control fabric in order to temporarily stabilize this area. The plan proposes to plant native trees and shrubs across the entire affected area. A total of eight trees were affected during the disturbance. All of the bigleaf maple trees that were cut were noted to be actively re-sprouting at the time of the site visit and their living root systems should continue to help maintain the structure of the slope. We are proposing to replace all affected trees at more than the required ratio (see attached Tree Retention Calculation Worksheet). Because of past pruning, affected trees did not have any significant diameter at breast height at the time of the current shortening. Diameters were measured at the point where the main stem was cut as indicated in the notes section of the Worksheet. From these measurements, it is possible to infer the necessary tree replacement ratio based on the diameter of the stem where it was pruned. From this analysis, it can be presumed that a total of four trees were affected that could be considered Significant per the Shoreline Municipal Code and four non-significant trees were affected, indicating a required replacement of ten trees. This planting plan proposes that an additional tree is planted for every affected non-significant tree. In addition, we are recommending that smaller tree stock is used to reduce slope disturbance during planting, and therefore propose to increase tree replacement by an additional four trees (30%). The total number of installed replacement trees will be 18 (see proposed plant selection below). In addition to the replacement trees, the entire affected area will also be planted with a variety of shrub and groundcover species (see below) in order to revegetate the affected area and stabilize the slope. All trees will be planted on approximately 10 foot centers and shrubs and low growing groundcovers will be planted on approximately 4 foot centers throughout. Shrubs and groundcovers should be selectively planted in groups or bunches of several different species in order to allow the plants best suited for the slope environment to eventually dominate the plant community (as recommended by WA DOE for slope stabilization and erosion control: Trailing groundcovers will be planted primarily on the steeper slope on approximately 2-3 foot centers interspersed with the bunched plantings. All plants should be installed in winter (November-January) for the most effective root establishment.

6310 NE 74th Street, Suite 201E, Seattle, WA 98115 phone 206.322.9296

Proposed species selection:

Planting Plan

Plant Species

Steep Moderate Slope Slope Size

Trees Vine Maple Black Hawthorn Pacific Crab Apple Cascara



Red Fllowering Current Serviceberry Snowberry Oceanspray Tall Oregon Grape Red-twig Dogwood Black Twinberry Thimbleberry






Sword Fern Salal Coastal Strawberry

15 10 75




Apprx. distance on center

18 6 6 4 2

1 gal 1 gal 1 gal 5 gal

18 6 6 4 2

10 feet 10 feet 10 feet 10 feet

55 10 5 10 5 5 10 5 5

1 gal 5 gal 1 gal 1 gal 1 gal 1 gal 1 gal 1 gal

85 20 5 25 5 5 10 5 5

4 feet 4 feet 4 feet 4 feet 4 feet 4 feet 4 feet 4 feet

1 gal 1 gal 4 inch

120 25 20 75

4 feet 4 feet 2-3 feet

20 10 10



Actual species and size may differ based on availability. Replacement species should be native to the Pacific Northwest and demonstrated to provide erosion control and slope stabilization such as those found on the WA DOE Plant Selection Guide ( All plants will be potted material and will be planted following typical installation techniques:      

Loosen roots from soil, cut any circling roots, and remove as much of the pot substrate as feasible (not into the planting hole). Dig the planting hole at least twice the width of the root mass. Arrange the roots evenly in the hole so they spread out and do not circle. Backfill with native soil so root flair is even with grade and gently push down to ensure that there are no air pockets Create a shallow basin around the planting hole to catch water where appropriate. Place a ring of arborist chips or composted bark around each plant at least six inches deep for moisture retention and weed suppression

6310 NE 74th Street, Suite 201E, Seattle, WA 98115 phone 206.322.9296

Special considerations for planting on steep slopes:  

Adjust grade around the planting hole as necessary to create a level area for installation. Cut through erosion control fabric (where present) in a large enough radius in order to access the soil for one gallon plantings.

 

Spreading ground cover in 4” pots can be installed in smaller holes through the coir. Bunch plantings above installed coir logs for additional stability where possible.

4. Maintenance Plan After planting (see Planting Plan above), the site will need to be maintained to ensure that the installed plants remain healthy and become well established. Because of the aspect and exposure of the slope, it is recommended that plants are irrigated during the dry months (June through September) for the first two growing seasons. This could be accomplished with a drip irrigation system or similar watering methods. The site will also need to be regularly maintained and cleared of encroaching invasive species. In lieu of regular spot weeding, it is recommended that a landscape crew visit the site at least twice a year for the first five years to remove or treat any weedy invasive species, taking care to not disturb the slope or the native plantings.

5. Monitoring Plan An EarthCorps Ecologist will monitor the site for a minimum of three years to ensure adequate survival of all planted trees and shrubs. Monitoring reports will be prepared and submitted to the homeowner at the end of each year. Reports will provide maintenance recommendations for the following year and provide a vegetation replacement contingency plan in the event of any diminished performance or mortality of the installed plants, as per standards identified in SMC 20.80.350(G). All installed trees will be mapped and inventoried to ensure survival. In order to track vegetation success of the shrub and groundcover plantings (excluding trailing groundcovers), monitoring plots (or belt transects) will be established within one month of plant installation to establish an asplanted baseline. Sampling unit size will be determined on-site in a manner that ensures that at

6310 NE 74th Street, Suite 201E, Seattle, WA 98115 phone 206.322.9296

least twenty percent of all installed shrubs and groundcovers are accounted for. All tree mortality will be replaced at a one to one ratio ensuring a greater than eighty percent (80%) survival rate through the third year of monitoring. Shrub and groundcover (excluding trailing groundcovers) will be replaced at a one to one ratio if percent mortality is projected to be greater than twenty percent (20%) of the as-planted baseline. Overall cover of native shrub and groundcover species will be greater than eighty percent (80%) following the third year of monitoring. In addition, percent cover of invasive vegetation will be estimated within each plot and compared against a twenty percent (20%) threshold. Tree, shrub, and groundcover replacement plant species will consist of those planted species observed on-site to have successfully established within the restoration area. Monitoring visits will occur three times in the first year (one as-planted baseline, one spring visit, and one end of summer monitoring visit) and then once a year at the end of each growing season (before the end of August) thereafter. If monitoring in the third year indicates poor performance and contingency is still necessary, the site will be monitored for an additional two years. Monitoring Performance Standards: 

Performance Standard 1: Planted tree and shrub material will have an eighty percent survival rate through the third growing season following planting.

Performance Standard 2: Native or desirable understory vegetation (woody shrubs, groundcovers, or other desirable understory or emergent plant species) will exceed eighty percent cover after the third growing season following planting. Appropriate species of native volunteer plants can be included in these measurements.

Performance Standard 3: Invasive plant species will not exceed twenty percent cover in any monitoring year. Any plant listed as either a regulated noxious weed (Class A, B, or C) or non-regulated noxious weed (Class B or C) by the King County Noxious Weed Control Board will be considered an invasive plant species. In addition, select King County weeds of concern may also be considered if they pose a threat to the success of the plant installation, particularly hedge bindweed and/or bittersweet nightshade if present following restoration.

Monitoring Schedule and Reporting: 

 

Year 1 - three visits/reports: o As-built report completed within one month of planting o Spring Year 1 interim report o Fall Year 1 annual report Year 2 – one visit/report o Fall Year 2 annual report Year 3 – one visit/report o Fall Year 3 annual report

Additional reports may be required in years 2-5 if corrective plantings or other contingency actions are necessary.

6310 NE 74th Street, Suite 201E, Seattle, WA 98115 phone 206.322.9296

6. Contingency Plan: In the event that any monitoring visit or report indicates a failure to meet (or is projected not to meet) any performance standard, adaptive management will be necessary. Management actions could include (but are not limited to) any combination of the following: additional plant installation, substitution of plant species better suited to site conditions, additional or more concentrated invasive species management, supplementary erosion control measures, supplementary irrigation, or other measures deemed appropriate during monitoring. All contingency measures should be employed within three months following approval by the City.

7. Projected Budget The following information is provided as a best estimate for costs associated with invasive plant control, plant material, planting labor, and monitoring services. These prices may change and need to be renegotiated due to factors including availability of plant material, revisions to the planting plan, additional monitoring requests or frequencies, etc. and are provided here as estimates only. Revegetation Site prep (includes labor and costs of herbicide) Plant material (includes delivery) Planting (includes staging, installation, and mulch) Subtotal Tax (9.5% of labor and materials) Total

$ $ $ $ $ $

Cost 675 455 1,250 2,380 226 2,606

Monitoring Year 1 As-built monitoring visit and report Year 1 Spring monitoring visit and report Year 1 Fall monitoring visit and report Year 2 Fall monitoring visit and report Year 3 Fall monitoring visit and report Total

$ $ $ $ $ $

1,380 920 920 920 920 5,060

Monitoring (Contingency) Per additional monitoring visit/report as required



Total Projected Budget (excluding contingency)



Prepared by:

Nelson Salisbury, Ecologist EarthCorps [email protected] 206.322.9296 x214

6310 NE 74th Street, Suite 201E, Seattle, WA 98115 phone 206.322.9296

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