  We propose a very long baseline atom interferometer test of Einstein's
equivalence principle (EEP) with ytterbium and rubidium extending over 10m of
free fall. In view of existing parametrizations of EEP violations, this choice
of test masses significantly broadens the scope of atom interferometric EEP
tests with respect to other performed or proposed tests by comparing two
elements with high atomic numbers. In a first step, our experimental scheme
will allow reaching an accuracy in the E\"otv\"os ratio of $7\times 10^{-13}$.
This achievement will constrain violation scenarios beyond our present
knowledge and will represent an important milestone for exploring a variety of
schemes for further improvements of the tests as outlined in the paper. We will
discuss the technical realisation in the new infrastructure of the Hanover
Institute of Technology (HITec) and give a short overview of the requirements
to reach this accuracy. The experiment will demonstrate a variety of techniques
which will be employed in future tests of EEP, high accuracy gravimetry and
gravity-gradiometry. It includes operation of a force sensitive atom
interferometer with an alkaline earth like element in free fall, beam splitting
over macroscopic distances and novel source concepts.
