The cache is not at the posted coordinates, though it is an interesting locale. (You could even ask the residents for some hints, but they may not be of much help.) D rating is due to having to complete the lab first; the cache itself is more of a D 1.5.
The actual coordinates can be found in the answers you uncover in the Charming Chesterfield Adventure Lab. Fill in the blanks: N42 53.ABC W 072 28.DEF and check your answer below.
If you Choose, you will have a Chance to explore some of Chesterfield’s Charming hiking trails once you find the bonus cache. Cheerio Chums!