Encinitas Municipal Code § 3.4 Greenbelt Mitigation Program

Landscaping is a critical element in the design of the greenbelt area located adjacent to the west side of El Camino Real in the Green Valley Planning Area. Portions of the drainage channel planned adjacent to El Camino Real and the surrounding greenbelt shall restore existing riparian habitat, while establishing additional riparian vegetation. A mitigation program shall be prepared and submitted to the City for approval concurrently with the first Tentative Map(s) for development in Green Valley. The goals of the project mitigation include the realignment and revegetation of portion of Encinitas Creek and its on-site tributary to:

The mitigation program will result in the reconfiguration and reconstruction of the drainage swale that parallels the western side of El Camino Real, as well as the revegetation of the swale with native riparian and wetland plant species. At a minimum, the mitigation program shall contain the following:

For landscaping purposes, the riparian area is divided into two zones based upon differences in soil moisture content and frequency of inundation. These zones are: 1) the Riparian and Floodplain Zone which contains fresh water marsh, southern willow scrub, and mulefat scrub vegetation; and 2) Upland Transitional Zone which consists of plant species typically found in drier and upland areas. Still another type of landscaping will be necessary for the urban runoff cleansing basins. The following guidelines will ensure vegetation stability, appropriate habitat value, proper maintenance, and attractiveness.

A. Riparian and Floodplain Zone

This zone is subject to periodic inundation. Plants in this zone must be able to tolerate periodic wet soil conditions. A selection of trees, shrubs, and ground covers should be utilized to accomplish the following:

1. Stabilize the floor and fringe of the basin to prevent erosion.

2. Filter urban runoff to help cleanse discharge.

3. Reduce local water velocities to induce better settling characteristics.

4. Bind sediments to prevent resuspension.

5. Conceal and trap trash, debris, and other floating objects.

6. Create cover, habitat, and food for wildlife.

7. Keep the soils of the basin floor drier by increased plant transpiration.

8. Break up engineered contours through strategic placement of trees and shrubs.

9. Tolerate exposure and compacted soils, and have minimal maintenance requirements.

10. Establish vegetation that requires minimal maintenance.

11. Allows the sediment control basin and the cleansing/urban runoff basins on-site to effectively remove sediments and urban pollutants from urban runoff flows.

B. Upland Transitional Zone

Plants in this zone are seldom inundated. Appropriate plant species selected for this zone will depend on local soil conditions and exposure levels. The design objectives for this zone are as follows:

1. Plant materials shall be selected and placed to ensure soil stabilization and urban runoff filtration and cleansing.

2. Plants should not conflict with adjacent open space uses.

3. The design should provide for visual appeal, wildlife habitat and low maintenance.

C. Urban Runoff Cleansing Basins

The purpose of these areas are to trap pollutants generated from urban runoff, especially during early season initial rains. Low flow drainage from parking areas are collected and diverted into these basins. Pollutants remain within the basin areas and percolate or are consumed by specialized plant materials. High flow storm drainage bypasses this system and is not processed. The planting scheme for the basin areas shall meet the following objectives:

1. Plant materials shall be able to withstand periodic saturation of root zone, as well as survive occasional submersion.

2. The variety of material (mainly grasses) function in the uptake, filtration, and/or consumption of runoff pollutants, nutrients and sediments.

3. The design of the area must allow for occasional maintenance.

4. The basin areas should be provided with an aesthetic blend of appropriate plantings, which fulfill the design objectives and create transition into adjacent zones.

A. Planting Procedures

Storm water management basins and channels are often a harsh environment for establishing vegetation. The following landscaping procedures should be utilized to enhance survival rates.

1. Embankments and basin side-slopes are often compacted during construction to ensure structural stability. The density of compacted soils prevents extensive root penetration and, therefore, larger holes must be dug and backfilled with uncompacted soil to accommodate the root systems of trees and shrubs.

2. The use of regionally native plant species is recommended. These plants require less maintenance and are better adapted to local climate and soil conditions, and are thus more likely to survive.

3. To establish the riparian area, live plants or dormant rhizomes should be transplanted from nursery stock. Hydroseeding shall occur concurrent with completion of planting.

4. At least two primary species, which are hardy and rapid colonizers, should be planted over approximately 30 percent of the total riparian area. Each primary species should be planted in three or four monospecific stands, with individual plants spaced two to three feet apart. Next, two or three secondary species that are not as aggressive in colonizing, should be randomly distributed in groups around the perimeter of the wetland.

5. Since the basin will be fully exposed for a number of years after construction, plant species that require shade or are susceptible to weather conditions such as wind damage, should be avoided except where protected.

6. Extra maintenance including watering, support, fertilizing, mulching, weed suppression, selective thinning, etc. is required in the first few years to ensure plant stability.

7. A temporary irrigation system shall be fully functional prior to planting and utilized until all plants are established.

B. Planting Palette

A detailed planting palette shall be established and incorporated into the Greenbelt Mitigation Plan as part of the mitigation plan for Green Valley. The planting palette shall consist almost exclusively of native and drought tolerant plant materials, except in those areas within the drainage channel that will be wet for most or part of the year. These areas should be planted with riparian and/or wetland vegetation, as appropriate.

To the extent applicable, all new development within the Encinitas Ranch Specific Plan Area shall be designed to be consistent with multi-species and multi-habitat preservation goals and requirements as established in the statewide Natural Communities Conservation Planning (NCCP) Act and shall comply with the City of Encinitas MHCP Interim Habitat Loss Permit Process, or shall obtain an incidental take permit under Section 4d, Section 7 or Section 10a of the Endangered Species Act as applicable. Compliance with these goals and requirements shall be implemented in consultation with the United States Fish and Wildlife Service and California Department of Fish and Game.

Paragraph added 8/23/95 (Reso. 95-91); amended 3/18/98 (Reso. 98-17)