Landscape Architect Articles

One Campus, 3 Drainage Solutions - Infrastructure Meets the Landscape06-10-16 | Feature

One Campus, 3 Drainage Solutions - Infrastructure Meets the Landscape
Landscape Architecture by Lynn Capouya, Inc. (LCI),
Landscape Architects, Irvine, Calif.
Lynn Capouya, Inc. Team: Jane Cataldo, Project Director; Soda Pay, Project Manager; Cong Phui, Irrigation Designer; Patricia Lear, Planting Designer

This detail and photo show one of the drainage swales constructed to keep the Lew Davis parking lot at Long Beach City College from flooding. Surrounding the parking lot are beveled rock lined dry creeks, or seepage pits, with landscape borders. What rain the plant roots don't absorb trickles down around the rock beds and down the slopes of the swales to the central low points where it percolates into a 3'-wide substrate of crushed rock that extends down as much as 13 feet.

Located in Long Beach, California, Long Beach City College (LBCC) www.lbcc.edu was founded in 1927. The college has two locations on 112 acres"?ua Liberal Arts campus and a Pacific Coast campus. The campuses offer 820 courses to a student body of 24,739. For those not familiar with greater Los Angeles area, the college is about 22 miles south southeast of Los Angeles International Airport.

Development of the landscape implementation plan(s) followed a series of three Long Beach City College (LBCC) campus master plan updates, and a campus-wide utility upgrade project. Lynn Capouya, Inc. (LCI) was contracted as a prime consultant to address critical problems identified in the infrastructure master plan. Those problem areas included drainage; hardscaping; irrigation; flooding; fostering water quality; facilitating watershed compliance; implementing an irrigation master control system to reduce water use; and providing sustainable planting solutions. The goal was to enhance the campus experience by developing functional and aesthetic guidelines for the ongoing bond construction program.

There are 12 granite benches (Southwest Boulder) on site; these are in the front quad. The natural stone seating is 2' x 6' and 18" tall. The granite is gray, but has rusty brown accents near the base. "Desert Gold' decomposed granite with stabilizer (Tri-State Materials) comprise the transition between the pavers and planting beds, which proliferate with orange Anigozanthos "Amber Velvet' Kangaroo Paws. Phoenix canariensis "Canary Island' palms dominate the lawn edges.

Following approval of the master landscape and irrigation improvement plans, LCI developed final plans for three key project areas: the Lew Davis parking lot; the front quad; and the central quad.

The day LCI began work, Lynn Capoya, ASLA, ISA, LEED AP, recalls Bill Adams, LBCC's bond management program director, in his wader boots, pulling a generator to pump out the Lew Davis Drive crosswalk. The adjacent parking lot had office trailers that were temporarily housing the bond management team. Those office trailers were to be removed and returned to a surface parking lot. The existing site was flat and clearly had poor drainage. Although rain in Southern California is something of a novelty and usually not that heavy, site runoff from the adjacent buildings and street inevitably caused flooding.

The landscape architects discovered the site had a high water table, and they were apprised of "potential archeological impacts" if excavation exceeded 13 feet. The proposed design thus employed concrete drainage tubes three feet in diameter, augured to a depth of 13 feet. The tubes collect the runoff from the street and adjacent buildings during storms and retain it in the managed drainage swale until the water can infiltrate first into the tubes and then through the clay soil and into the water table.

A rock-lined swale allows for first flush mitigation and reduces the capacity on the city stormwater pipes by retaining overflow. A drought tolerant plant palette was developed to reduce irrigation water and demonstrate that sustainable plantings could be both attractive and low maintenance. Site furnishings and hardscape was designed to create an inviting campus space for students, teachers and pedestrians.

The Long Beach City College front quad was flat and had no drainage; any rain equaled flooding. There were extensive utility and vault conflicts (e.g., chilled water for laboratories), plus no documentation (detail drawings) for some of the underground infrastructure. Space for drainage retention was limited to a few spots. The solution was a series of concrete dry wells (indicated by red dots) to retain water until it could infiltrate into the ground. The school did not want runoff from the front quad going into an already overloaded city stormwater system. The wells have a 4' interior diameter, with 4"-thick precast concrete liners; atop are 2'-sq. bolted cast iron grates labeled "Stormwater Only." Only overflow of these wells goes to the city stormwater system.

The first visit to the central quad revealed a surprisingly large population of rabbits, the result of people releasing domesticated rabbits. With a no kill policy in place, LBCC captured and spayed the rabbits to naturally decrease the rabbit population. The landscape of course had been breakfast, lunch and dinner for the rabbits and was in distress at all levels.

At the Central Quad, there was significant grass area that allowed for underground water capture and retention of runoff. Two options were explored as water retention opportunities. Option 1 included a large horizontal system of tubes; option 2 was an egg crate structure of cubes. Because the site was so flat, and the current city system was so undersized, street capacity was not available. The goal was to maximize water storage. Further, due to the additional hardscape being added into the quad, there was additional storage capacity needed to capture and slowly release water into the city's storm drain system. Option 1 drainage was selected because tubes are easier to clean out. Additional consideration was given to the concept of potential reuse of water for irrigation. After a cost benefit analysis, it was determined that the additional $100,000 in infrastructure cost for the potential one month of storage capacity, if rainfall occurred in a given year, was not an optimum use of funds. Further, reclaimed water was already in place and was being designed for irrigation into these areas. Had only potable water been available, further consideration of reuse would have been warranted.

The central quad also had a flat terrain with an undersized drainage system. The large grass areas (balanced by drought-tolerant plantings) allow for underground water capture and retention of runoff.

The front quad and the front door to the campus were also a flat site with poor drainage. There were also significant utility and vault conflicts, including chilled water for building cooling. Some underground facilities were not documented. Space for drainage retention was limited to a few spots that would allow a series of concrete dry wells to be used to retain water until it could infiltrate into the ground. This water was not allowed to go into the stormwater system.

For the central quad, a horizontal system of 8' diameter galvanized reclaimed water storage tubes was selected as the best water capture and retention option. This stored runoff is released slowly to the pump station in the central quad via concrete drainage tubes three feet in diameter, augured to a depth of 13 feet. The pump station regulates the release of this runoff to the street, where it flows into the city's stormwater system.

Irrigation
As part of the master plan work prepared for both the Liberal Arts and Pacific Coast campuses of Long Beach City College, Lynn Capouya, Inc., prepared a 25% schematic design for the irrigation systems.

The existing systems were inventoried and a campus wide program was developed. The LBCC campus had recently brought reclaimed water on site and selected the Calsense irrigation control system, for which LCI designed master distribution within limited watering windows. A key goal was to reduce and consolidate smaller individual controllers into the new master system, complete with flow sensors, moisture sensors and remote programming to more efficiently manage irrigation campus wide. A drought-tolerant plant palette, including ornamental grasses, succulents and other selected plant materials, was also specified. Turf was reduced, but retained as a campus feature.

The day the landscape architects began work at Long Beach City College, Lynn Capoya, ASLA, ISA, LEED AP, saw a generator pumping out standing water from the Lew Davis Drive crosswalk. The parking lot flooded with most any rain. The design solution was managed drainage swales and plantings. The red dots on the rendering indicate the drainage sumps.

In summary, from LCI's landscape master plan concept for Long Beach City College, three key project areas were demonstrated using three different types of drainage facilities. Each individual area was evaluated, recognizing the associated opportunities and constraints to develop the best value for the LBCC campus.