ENVIRONMENTAL INITIAL STUDY

1.0 BACKGROUND INFORMATION 1. Project title: Parcel Merger and Expansion of Athletic Fields with a New Track and Artificial Turf Infill 2. Lead agency name and Town of Portola Valley address: 765 Portola Road, Portola Valley, CA 94028 3. Contact person and phone Tom Vlasic, Town Planner number: (650) 851-1700 4. Project location: Woodside Priory School 302 Portola Road, Portola Valley, CA 94028 Assessor Parcel Numbers (APNs): 079-053-130, 079-053-140, 079- 053-050, 079-220-040, and 079-053-420 5. Project sponsor's name and Tim Molak, Head of School address: Woodside Priory School 302 Portola Road, Portola Valley, CA 94028 (650) 851-8221 6. General plan designation: Institution 7. Zoning: R-E/1a/SD-1a(Residential Estate/Slope Density/1 acre) 8. Description of project: The proposed project is an application for amendment of Conditional Use Permit (CUP #X7D-3), parcel merger, and expansion of athletic fields with new track and synthetic turf infield. The expansion of athletic fields would include removal of a portion of the existing natural turf area, and replacing that same area with a synthetic track surface with a synthetic turf infield as specified by the applicant. Secondary improvements include an asphalt driveway, removal of existing volleyball facilities, construction of a new storage shed, construction of necessary subsurface drainage improvements, restoration of native landscaping and trail improvements, earthwork, and sewer pipeline relocation. Earthwork will include removal and re- contouring of an existing berm, with the cut material used onsite as raised fill under the track and field area. Cut and fill material is proposed to balance on site. 9. Surrounding land uses and The project site is located on the Woodside Priory School campus. setting: The project site is surrounded by Portola Road to the southwest; soccer field to the northwest; faculty offices, academic resource center, and classrooms to the north; student residences to the east; and low density residential to the southeast. 10. Other public agencies whose None approval is required

Town of Portola Valley Woodside Priory School Field Improvements November 2012 Initial Study/Proposed Mitigated Negative Declaration

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PROJECT LOCATION The proposed project is located within the Town of Portola Valley, on the southern bayside portion of San Mateo County commonly referred to as the “Mid Peninsula,” as shown in Figure 1, Regional Location. The Portola Valley planning area is located west of Stanford University and extends outside the town’s incorporated boundary totaling approximately 12,000 acres, whereas the town occupies approximately 5,785 acres. This area of the Mid Peninsula consists largely of a scenic valley bisected by the San Andreas Fault, with steep, rugged terrain and mountains on the west and lower more gently rolling hills to the east.

The project site is located entirely on the Woodside Priory School campus, a private school located at 302 Portola Road, Portola Valley, as shown in Figure 2, Vicinity Map. Woodside Priory School is a co-educational, independent, Catholic college preparatory school for 6th through 12th grades. The campus serves approximately 350 students and is located on 50 wooded acres in a rural setting. The school campus contains approximately 23 campus facilities/structures, including a three soccer fields, two baseball/softball fields, four tennis courts and a cross country course. Photographs of the existing campus and playing fields are shown in Figures 3a through 3c. The proposed project would include alterations to the existing four-acre softball outfield located along the southwest boundary of the school campus and a portion of the property located at 210 Portola Road (newly acquired Rutherford parcel).

EXISTING AND SURROUNDING LAND USES The project site is designated for “Institution” land uses in the General Plan and zoned R-E/1 acre (Residential Estate/1 acre) with one parcel, APN 079-053-014 (the newly acquired Rutherford parcel), designated R-E/1 acre/SD-1a (residential estate, one acre minimum parcel area and slope density one acre combining district). According to the Portola Valley General Plan Comprehensive Plan Diagram, the campus is surrounded by “Low-Medium Residential” land uses (Town of Portola Valley, 2010a).

The project site is bounded by the following land uses: Portola Road, a locally designated scenic roadway to the southwest; school soccer fields to the northwest; faculty offices, an academic resource center, and classrooms to the north; student residences to the northeast; and low density residential to the southeast as shown in Figure 4.

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PROJECT DESCRIPTION AND CHARACTERISTICS The proposed project includes an application for amendment of Conditional Use Permit (CUP #X7D-3), merger of parcels, and a site development permit for expansion of athletic fields with a new track and synthetic turf infield.

The objective of the proposed project is to merge a recently acquired property with the existing campus; update the existing conditional use permit to reflect the increase in the site area; construct a regulation 400 meter running track; and replace the existing athletic field with an improved field, such as synthetic turf, inside the track that will be more usable in wet weather and will provide more consistent playing conditions for sports.

Lot Merger and Amendment to Conditional Use Permit Conditional Use Permit (CUP#X7D-30) would be amended as follows: merge Assessor Parcel Number (APN) 079-053-140 with APN 079-053-130. This amendment would revise the total approved square footages allowed at final build-out as follows: amend the existing 49.109 acres campus to add 1.265 acres for a total amended campus area of 50.374 acres; amend the currently remaining allowable floor area by adding 1,500 square feet (SF) and subtracting 3,500 SF resulting in a remaining balance of 22,773 SF of allowable floor area; and amend the currently remaining allowable impervious surface area by adding 1,800 SF and subtracting 31,612 SF resulting in a remaining balance of 51,161 SF of allowable impervious surface area as summarized below. The proposed lot merger and newly acquired parcel (which includes the Rutherford parcel/Fromhertz House) are shown in Figure 5a.

Maximum Allowable Floor Area Scholastic Athletic Residential Impervious Surface Area (Square Feet) (Square Feet)

Current Remaining 2,570 7,000 15,203 80,973 Allowable Buildout: Rutherford Adjustment 0 0 1,500 1,800 Amended Remaining 2,570 7,000 16,703 82,773 Allowable Buildout:

Proposed Project:

Shed (0.05 acres) 0 -2,000 0 -2,000

Residence 0 0 -1,500 -1,800

Driveway (0.03 0 0 0 -1,240 acres) Track (0.61 acres) 0 0 0 -26,572

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Amended Remaining 2,570 SF 5,000 SF 15,203 SF 51,161 SF Allowable Buildout:

Field Improvements The proposed project includes a request for a site development permit that would allow the removal of a portion of the existing natural turf and athletic facilities from the outfield of the existing softball field, and replacing that same area with a synthetic 400 meter track surface (0.61 acres), with a synthetic turf infield (2.36 acres), as specified by the applicant, over a subsurface drainage system that will receive runoff from an area totaling approximately 3.03 acres (131,987 SF). Related actions would include removal of existing turf and field facilities, site preparation, installation of the subsurface drainage system, replacement of an existing 36-inch drainpipe, and installation of new field and track surfaces.

Existing natural turf will remain around the track area. Native landscaping along Portola Road and near the Rutherford parcel will be provided for visual screening purposes. Other improvements include installation of an asphalt driveway to connect the existing parking lot to the new field/track area, construction of a new 2,000 SF storage shed (with drinking fountains) in the vicinity of the existing volleyball court, and removal of non-native landscaping and planting of native landscaping. Field improvements are shown in Figure 5b. The softball outfield would be slightly graded to provide a smooth transition to the raised track surface. No improvements are proposed to the existing softball diamond, and no modifications are proposed to the structure on the Rutherford parcel. Grading and construction of site improvements are anticipated to occur over a two month period while school is out of session.

Demolition and Site Preparation Demolition and site preparation activities will include: stripping and removing the top three inches of the existing natural turf and surface soils; demolition and disposal of existing concrete drinking fountain (to be replaced near new shed); and removal of the existing volleyball court. Earthwork will result in the removal and re-contouring of an existing berm and relocation of an existing sewer pipeline. The 110,000 cubic yards of cut from the berm will be spread onsite as fill to raise the track and field area by approximately 10 inches. On top of the soil fill, drain rock would be imported and placed as part of the subsurface drainage system as described below raising the surface of the field an additional eight inches for a total increase in elevation of 18 inches above the current elevation. No off-haul of cut material is required, as cut and fill of soil material are proposed to balance. The entire field will be graded to retain the existing one percent slope (running south to north) (BKF Engineers, 2012).

Subsurface Drainage System According to the Drainage Report prepared by BKF Engineers in October 2012 (Appendix E), the project site will maintain existing grades and a gentle one percent slope from the south to the north. Surface flow and direct rainfall will drain through the synthetic turf layer and into a 4-inch thick layer of Class 2 permeable drain rock (BKF Engineers, 2012). A drain surrounding the perimeter of the track will collect and retain a portion of the runoff. Excess runoff will be conveyed to a rock Woodside Priory School Field Improvements Town of Portola Valley Initial Study/Proposed Mitigated Negative Declaration November 2012

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layer where it will be detained prior to being discharged to the existing 36-inch corrugated metal pipe (CMP) that is located along the western boundary of the softball field (BKF Engineers, 2012). The 36-inch CMP will convey runoff across campus where it will discharge to Corte Madera Creek at an existing outfall. The proposed drainage plan is shown in Figure 5c.

Track Surface The proposed project would include the installation of approximately 0.61 acres of an oval 400- meter athletic track surface with a straight-away along the northern side of the track and a mow band that is 4-inches wide on the outside perimeter and a 6-inches wide on the inside perimeter. The track surface product will be California Track & Engineering, Inc.’s Rekortan G-10 product (see Appendix A for additional product data). Rekortan G-10 consists of a two layer, 10 millimeter, impermeable surface as shown in Figure 6. The first (bottom) layer is a mix of Styrene-Butadiene- Rubber (SBR) rubber and a Polyurethane binder paved with special equipment. The next (top) layer consists of Polyurethane/ Ethylene Propylene Diene Monomers (EPDM) that is applied in three coats. As a final step the track would then be striped.

Synthetic Turf Background Synthetic turf (also referred to as artificial grass) is a surfacing material that has been used to imitate grass since the 1960s. Synthetic turf is generally used where natural grass cannot grow, or when maintenance is costly, difficult, or undesired. Within the last 20 years, the use of synthetic turf has become increasingly popular for athletic fields; however, it is also used on playgrounds, at private residences, and in other outdoor spaces. Example of Installed Track and Field Materials

In the early 1970s, there were many concerns regarding the safety and performance quality of synthetic turf. During that time certain installations of synthetic turf would wear quickly, seams would fail, and the top layer would degrade from exposure to sunlight. Synthetic turf was suspected to cause friction burns, blisters, and other injuries. In addition, it was found that synthetic turf did not have the same cooling effects as natural turf, and surface temperatures could be up to 30°F warmer on synthetic turf fields. Athletes claimed that balls would bounce harder and roll faster and in less predictable ways, directly affecting games.

Since the 1970s, significant research and development has occurred within the synthetic turf industry and the technology has improved to address these earlier concerns. Today, synthetic turf systems incorporate infill material to help keep the simulated grass blades vertical and to ease impact to the surface. Monofilament fibers that simulate grass and are long lasting; the seams are now sewn together rather than glued; and the turf systems are now multi-layered similar to natural turf. Research has found that synthetic turf systems of today are more stable, firm, non-abrasive and

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non-spongy compared to the original systems. Some studies have found that certain synthetic turf systems reduce some types of injuries when compared to natural turf (TRC, 2008).

Installation The proposed project would replace approximately two acres of existing natural turf with FieldTurf’s “Revolution” fiber product and “EcoGreen Plus”