From January 29 through the end of February, MEMBG received more than twenty-three inches of rainfall--seventeen rain days during a thirty-one-day period. The heavy rains tested several of our major construction projects, and very quickly we discovered what worked and what didn't.
Let's turn first to the Hershey Slope restoration project. From the last newsletter, you learned about our mud woes of January 1995, when heavy rains caused a section of Hershey Slope--more than 100 cubic yards--to wind its way, like lava, into the garden. It was both awe-inspiring and distressing to see trees swept seventy-five feet, with entire root masses intact. With FEMA funding, in fall 1997, outside contractors installed a retaining wall, twenty-eight by seven and one-half feet, with a concrete swale to redirect water runoff above the wall. UCLA project manager Clint Fulton who oversaw the contractors, at our urging pressed for completion, and the project was finished by the third week in January. Garden staff had little time to finish grading, soil stabilization, and planting below the new wall before the rains arrived.
We laid down 900 square feet of one-inch coconut fiber jute netting on Hershey Slope. Then we seeded the slope with fourteen species of fast-growing, deep-rooted California coastal range wildflowers and the native, perennial sheep fescue (Festuca ovina) that is often used for soil stabilization. Afterward, we covered the seed with one-half inch of an organic soil mix and watered it in. There was concern about covering the area with plastic, as well, to protect the freshly sown seed from being washed away. But we trusted the jute, with its ability to slow and diffuse water runoff. That strategy allowed the seeds to germinate and the plants to begin their job as ground covers, protecting the soil. Considering the late planting and rain intensity, the jute performed admirably.
Receiving not so high a grade was the drainage in several areas of the new path that connects the new entrance on Tiverton with The Nest. While some parts of the path responded to the challenge of a deluge as expected, the same construction techniques proved inadequate in other sections that had to endure higher water volume due to accumulations of slope water runoff. In those places, subsurface drains did not prove sufficient. The decomposed granite with its binding agent "Stabilizer" washed away, causing some surface erosion.
To remedy path erosion for the future, we will install additional collection drains at ten-foot intervals, wherever excessive water runoff occurred.
As a member of this institution of higher learning, I learned some valuable lessons about protecting hillsides and drainage when tested by El NiŅo. And, like the students, I am looking forward to spring break!
RAND PLEWAK (Garden Manager)