"Foundations, Retaining and Earth Structures" by Tschebotarioff, second edition quotes the NYC building code and for the SM material indicated allowable bearing value of 6 - 3 tons.SF. No info on density.
"The Design of foundations for Buildings" by Johnson and Kavenagh, 1968 on page 163 is quoted. This is for the SM, SW and SP sands, generally below the #4 sieve.
"N valuers not withstanding, experience seems to indicate that the bearing value of sands need not be taken as less than 2 tons per square foot,, unless some special consideration of impact or vibratory loading (earthquake , for example) exists." Although they say it depends on compaction and grading.
I'd look at where it sits as to relative density. 95% of Modified probably is way up there, near 100%
"Foundation Engineering" by Peck, Hanson and Thornburn, on page225 has a chart with N values, footing width and bearing showing a 5 foot wide footing with N about 22 (high medium density, settles 1 inch on sand. No indication of what kind of sand.
I'd want to be on site and do some probing and cone tests before saying OK, along with the 95% of Modified. By force of habit, I think my usual high for sand is 4,000 psf, but mainly because it works and no settlement problems result. Plate load tests have shown that as "safe" on fine to medium sand, extrapolated to typical footing sizes. That may be conservative however.
A final statement. N values are meaningless on uniform sands in my opinion. Reason: very small range of relative density, loose to dense.