How to reconcile non-attachment in a Type-A, North American culture where work is life? I've been meditating on-and-off for years.

However, the non-attachment preached by the Buddha conflicts with the environment around me. I'm in a large urban center in North America. 

Achievement is valued; I feel like I'm contributing to the world in a small way. 

I feel like it makes me better at my job to dream big and get attached to goals big and small, whether it's mentoring someone junior or committing years to a project that has an uncertain payoff.

This puts me at odds with my meditation practice, where "letting go" is emphasized.

The best resource I have found specifically addressing this question is Stephen Batchelor's book "After Buddhism". In it, Batchelor lays out one possible interpretation of the scriptures, in which the Buddha and his disciples are very much 'in the world'---businesspeople, merchants, town doctors, etc.---this was refreshing to read and made me feel more at ease. 

Am I asking to eat my cake too? I value Buddhism and meditation, but I also value my Western individualist roots and feel egoistic achievement is necessary for progress in science and technology.

Thank you!
Firstly, I am very much against this pop-culture Buddhism where too much emphasis is given to letting go and not that much emphasis on Bhavana and development of wholesome qualities. Letting go of what, exactly? Definitely, check out Thanissaro Bhikkhu's talks on YouTube who shares a similar opinion. There are many things which we need to let go: anger, jealousy, rage, covetousness, stinginess, delusion etc. There are many things we need to develop or "acquire": Metta, Compassion, Euqanimity, Mindfulness, Patience, Humility, Wisdom etc. Knowing which qualities are wholesome and developing them and which are unwholesome and letting go of them is practical wisdom.

Why does achievement need to be egoistic? Why not process and vision driven? We can always frame "achievements" as something bringing long term happiness to ourselves and the people around us instead of something "I" have added to my shining Resume. If that is the case, then no need to hesitate in pouring our energies into it; unless you realise later that this is not really the case.

A very interesting Theravada list is the four Iddhipada (four bases of mental power) cultivated for success in spiritual practice but equally applies in lay achievements. They are Chanda (Desire or Aspiration), Viriya (Energy), Citta (Keeping the Goal in mind), Vimansa (Review or Investigation of results to adjust). So, the Buddha is not against being competent, efficient and energetic in achieving your goals. Quite the opposite, he encourages it.

Also, don't worry about ego too much. Even third path Anagamis have conceit. It is a very deep fetter. So, don't be too worried about it as long as you are aware of it. Even, Ananda the Buddha's attendant once mentioned that we use conceit to overcome conceit (for example to be regular in practice), and moderation in eating to overcome sense desire. Otherwise, you would be going to the extreme of self mortification, which is ignoble and of little benefit.

Hope, this helps.