This is one of those, 'I wonder what that door in the sound wall is used for'.
If you are observant, which most geocahers are, you have probably seen some of them along the freeway in your travels.
Thanks to cjspontiac for the purpose of the door in the sound wall.
There is a twofold purpose.
First and foremost for emergencies.
If police and fire cannot access an accident on the freeway due to traffic jams, they can always access through the residential area with vehicles and charge to the action with themselves and small equipment through the freeway access doors.
The second purpose is for maintenance. Should sound wall maintenance be required for any reason, the safer access for the maintenance is through the access doors instead of by way of the freeway.
This is not your easy find so figure for about 5 to 15 minutes as it has less volume than a 35mm film container.
As any good geocacher would do, bring your own writing tool. Parking is close by and respect the neighboring houses close by.
If you want to stroll around there is common greens and a playground nearby for the kids especially if it takes you a long time to find which for some, well maybe a lot of you.
Updated 160318
The difficulty level changed to 4.0
Added another hint 160318.
NOTE: if you find that someone has parked nearby and you don't want to "APPEAR" in front of them travel North and exit into the park area.
Please put the cache back where you found it. It keeps
the public from finding it or being curious
and gives the cachers following you the same challenge.