A good guestimate is that you would need to add about 1.82 lbs. of actual N to achieve a C/N ratio of 30/1.

1.82 lbs. of N required / .02 = 91.0 lbs. of coffee grounds.
1.82 lbs. of N / .15 = 12.13 lbs. of urine. (or, just shy of 1 1/2 gallons.)
Of course, these are estimates because things vary in the real world.

I would guess that a good portion of the nitrogen would be lost to volatilization from urine so you'd probably have to add more than that.

Math below if anyone is curious about how to do it.

The organic content and nitrogen percent will vary based on the type and age of the leaves but here are a couple of decent ball park figures to work with.
(on a dry weight basis):
95% organic matter
1.0% - 1.5% nitrogen (let's say 1.25%)

300 lbs. of leaves X 0.95 = 285 lbs. of O.M.

To estimate the carbon percent, divide the organic content by 1.7:
285 lbs o.m / 1.7 = (roughly) 167 lbs. carbon

167 lbs. carbon / 30 = 5.57 lbs. of N required for a C/N ratio of 30/1

Of course, we need to factor back in the nitrogen already in the leaves: .0125 X 300 lbs of leaves = 3.75 lbs. of N:
5.57 lbs of N required - 3.75 lbs. of N in the leaves = 1.82 lbs. of N required for a C/N ratio of 30/1 in 300 lbs. of leaves by dry weight.

Thanks for the info. and doing the math.
That is a heck of a lot of stops a Starbucks. I will probably continue making my daily stop but manure from a cow lot seems like a much better way. Cow lot manure will have a lot of urine since they are confined.

I don't know if it could be a problem for you, but manure from CAFOs has many potential issues, particularly for an organic gardener.
Got any pastured animals in your area?

I get the manure from my own barn so I know it is clean so to speak. As far as pastures are concerned you need to watch out for those that use herbicides. For instance Grazon has a residual that can be past on into the garden killing broad leafs. Which, of course, is what we mostly plant. Using hay or straw, directly or fed to the cow, can have the same type of herbicides.