For much of the way, Imperial Highway is signed as State Route 90. A de facto freeway portion of the route in Yorba Linda is also known as the Richard M. Nixon Parkway. The portion in Los Angeles County is located about one mile north of, and runs parallel to, Rosecrans Avenue.
Are areas of your lawn bumpy and uneven? When you walk across these areas does the soil sink or feel soft? If so, some type of soil dwelling critter is probably the cause. During winter the activity of moles, earthworms, and mole crickets can cause mounds and tunnels in lawns that result in uneven or rough patches. To fix these problem areas you must first diagnose which critter is causing the damage. Earthworms.
If you have seen this, then you may have a thriving population of earthworms. Often earthworms leave small mounds or clumps of granular soil, which are called castings, scattered about in the lawn or garden. The castings may be seen as a nuisance when they accumulate. This situation is often noticed in fall, winter, or spring when warm season grasses are dormant or grow slowly.