ASCE Los Angeles Section

Ojai Meadows Preserve (400 S Lomita Ave,  Meiners Oaks, CA)

The project is located in the County of Ventura unincorporated community of Meiners Oaks in the upper Ventura River Watershed (VRW). This watershed is subject to Total Maximum Daily Loads (TMDL) for Algae, Eutrophic Conditions, and Nutrients in Ventura River and its tributaries. The County of Ventura in cooperation with the Ojai Valley Land Conservancy (OVLC) constructed Happy Valley Bioswale, an enhanced vegetated swale, to reduce urban runoff pollutant loading to the Happy Valley Drain, a tributary of the impaired Ventura River. Typical swales range from 2-3 feet wide, about 100 feet long, and are 6 – 12 inches deep. Happy Valley Bioswale has a 10-foot wide flowline, is 45 feet wide at ground surface, has a maximum depth of 3.5 feet, and is 300 feet long in a horseshoe pattern. This massive vegetated swale treats runoff from 37 acres of urban area (40% of the Meiners Oaks community area) for treatment of an estimated 1.6 million cubic feet of annual runoff. The $400,000 construction was primarily funded by the Proposition 84 Stormwater Grant Program.

A diversion structure was constructed to intercept flows from an existing 24-inch diameter County storm drain pipe that parallels the project site. The swale was enhanced with incorporation of a high-flow nutrient removal baffle-box to pre-treat the water allowing settlement of sediment and capture of trash and vegetative debris prior to entering the swale. The water then flows through the vegetated swale removing additional pollutants by natural filtration, minor infiltration and evapotranspiration. An inline check valve has been installed at the end of the swale where it discharges back into the existing storm drain to prevent backflow into the swale during large rain events.

1) This is a successful demonstration of a collaboration between Public Agency and Land Conservancy to implement Low Impact Development (LID) system for stormwater quality improvement, and an integration of land and water resources management with an excellent opportunity for education and outreach.
2) Not being able to rely on infiltration for volume reduction meant that we had to reconnect to the existing storm drain in order to release treated water. This provided the added challenge of BMP selection and sizing to meet project goals while working within the minimal 1.5-foot elevation difference from inlet to outlet due to the flat slope of the existing storm drain. Both enhanced box/vault features had to have matching inverts for inlet and outlet which restricted proprietary device selection. The swale couldn’t be very long since the miniscule elevation drop across the site could easily render the swale flat and be a cause of concern for drainage and mosquito/vector issues. As such, the swale was set to the maximum length that drainage and grade could ensure drainage. The swale was then widened considerably for increased treatment volume and given meandering 4:1 to 5:1 side slopes for visually pleasing curves so as not resemble a typical “engineered channel.”
3) A very unique feature of the diversion structure is that it has been designed to be adjustable. Mounting brackets within the diversion structure will hold a fiberglass reinforced polyester weir plate in place. Four (4) weir plates of different heights (6, 8, 10 & 12-inch) have been manufactured and provided by the contractor. This allows the County flexibility regarding how much water is diverted to the Enhanced Vegetated Swale. The treatment volumes estimated for the project are based on the 8-inch high weir plate installed. Therefore, based on post-construction flow and water quality monitoring data we can decide to substitute a taller weir plate to divert more water. Or, reduce the height of the weir plate to lessen the volume diverted (potentially an option if vegetation issues or erosion/scouring occur).
4) The initial application for grant funding in late 2013 included infiltration-based BMPs for the proposed site. However, in 2014, site-specific infiltration testing was completed which rendered infiltration technically infeasible due to extremely low soil percolation rates and high clay content. The 30% project re-design was completed to incorporate the filtration-based enhanced vegetated swale within 2 months before the full grant application was due.
5) We hope to show through our on-going post-construction influent and effluent monitoring that the Happy Valley Bioswale will exceed project pollutant removal goals and that vegetation establishment in poor draining soils can rebuild the soil structure improving infiltration rates and upgrading the swale to a semi-infiltration based BMP that will see measureable long term volume reduction, not just treatment. 

Happy Valley Bioswale project is a long-term collaboration between County of Ventura Public Works Agency and Ojai Valley Land Conservancy (OVLC) to capture and treat stormwater runoff from unincorporated community of Meiners Oaks to meet Clean Water Act/TMDL requirements. This project was constructed on the undeveloped Ojai Meadows Preserve site owned by the OVLC and has the support of the Surfrider Foundation, Santa Barbara ChannelKeeper, environmentally conscience community represented by the Ventura River Watershed Council, and local Chumash community. Through unincorporated storm drain network and impaired waterbody research as well as site suitability analysis the OVLC property was selected as the top alternative. Contact was made, discussions continued and OVLC staff were included in all design decisions and provided very valuable comments and suggestions in relation to aesthetics, footprint location, maintenance access, as well as irrigation and planting. The OVLC feels very strongly that this project will be a large benefit to the community and their own property. In October 2014, an agreement was executed between OVLC and the County to construct and maintain the swale including the OVLC’s long term operations and maintenance of the irrigation system and vegetated portions of the project.

The public outreach and education aspect of the project is huge. The site is a favorite local spot for relaxing walks and nature experience. It is directly adjacent to Meiners Oaks Elementary School (MOES) that receives high pedestrian and vehicle traffic. The swale is providing community improvement by adding environmental benefit as well as aesthetically pleasing vegetation on a previously barren parcel. Education was factored into the design by providing a marine-grade fiberglass observation lid on the nutrient removal baffle box. An educational kiosk is under design scheduled for installation in March 2016. In addition, grant funding includes implementation of an Ocean Friendly GardenTM (OFG) at the MOES site, next to the project site, by students and volunteers through Green Garden Group’s 5-workshop series in September-October 2016. This involves the community members as well as non-profit organizations and provides valuable hands-on education on effective ways to convert turf lawns to aesthetically pleasing and drought tolerant landscapes. More info about OFG program is available at http://www.greengardensgroup.com/ Ribbon cutting ceremony is scheduled for March 4, 2016 and an agenda is currently being developed.

Uploaded as part of the “additional documents” are the design plans for swale details and unique design features such as the pre-treatment baffle box and adjustable diversion structure. Additionally, photos of construction have been provided to better illustrate the size of the swale, the uniqueness of its features, and some neat aerial shots taken from a drone before and during construction.

The County of Ventura in cooperation with the Ojai Valley Land Conservancy constructed Happy Valley BioSwale, an enhanced vegetated swale, that will treat 1.6 million cubic feet of urban runoff annually from 37 acres of the unincorporated Meiners Oaks area in an effort to improve water quality in the Ventura River Watershed and meet Clean Water Act/TMDL requirements. Construction was primarily funded by the Proposition 84 Stormwater Grant Program.

The County of Ventura in cooperation with the Ojai Valley Land Conservancy constructed the Happy Valley Bioswale, an enhanced vegetated swale, that will treat more than 1.5 million cubic feet of urban runoff annually from the unincorporated Meiners Oaks community in an effort to improve water quality in the Ventura River Watershed. The swale is constructed at Ojai Meadows Preserve site, a favorite recreational spot in the area. Construction was primarily funded by the Proposition 84 Stormwater Grant Program.

The Happy Valley Bioswale has a 10-foot wide flowline, is 45 feet wide at ground surface, has a maximum depth of 3.5 feet, and is 300 feet long in a horseshoe pattern. A diversion structure with adjustable weirs was constructed to intercept flows from an existing 24-inch diameter County storm drain pipe that parallels the project site. The swale was enhanced with incorporation of a high-flow nutrient removal baffle-box to pre-treat the water allowing settlement of sediment and capture of trash and vegetative debris prior to entering the swale. The water then flows through the vegetated swale removing additional pollutants by natural filtration, minor infiltration and evapotranspiration. An inline check valve has been installed at the end of the swale where it discharges back into the existing storm drain to prevent backflow during large rain events.

The site is directly adjacent to Meiners Oaks Elementary School with high pedestrian and vehicle traffic making it an ideal site for public education opportunities.  As such, the baffle box was designed and constructed with a marine grade fiberglass observation lid that allows passersby a visual of how the unit removes pollutants during a rain event or a visual of all the captured sediment, trash and debris after rainfall has finished. The swale is providing community improvement by adding environmental benefit as well as aesthetically pleasing vegetation on a previously barren parcel.

Future implementation of an Ocean Friendly GardenTM as part of this project through 5-workshop series at the adjacent Meiners Oaks Elementary School is expected to have high community involvement.

Please see additional documents uploaded with nomination.