Possibly expand my real estate footprint on the side as well.

A lot of time the lender's that'll do HELOCs on investment properties are local/regional banks with local/regional footprints.

We have all necessary permitting, environmental site assessments, and city and state approvals complete.

Question—will this need to be remediate according to MDE guidelines or can I just clean it myself and dispose of rags and oil environmentally?

Lately, the advice for latex paint in many cities is just to set it outside where pets, kids, and wild animals can't get into it, take the lid off, let the liquid evaporate, and just toss the rest in the trash - but ask your city to know for sure.The city's website will probably list the hazardous waste stuff under the environmental department (big cities), or probably water and sewer (smaller cities). 

90% to 100% CLTV is out there; quite often regional banks with a regional footprint.

The best you would be able to get is a Letter of Environmental Protection, which tells everyone you did illegal work then hired a licensed deleader in to fix it.

Could phase 1 environmental study be a deal breaker?

The development process starts with site selection appropriate for the number of units you would like to build, then you hire a civil engineer to do surveys, site planning, soils and environmental in order to begin the entitlement process, then you get an architect to design the product, then you get bids from multiple contractors.

Tenant shall be held responsible for water damage caused by overflowing toilets and/or drains.Take no action which would cause a cancellation or increase in Landlord’s fire or liability insurance.Obey all environmental laws and keep no toxic, inflammable or dangerous substances on the Premises.Prevent the accumulation or buildup of mold or mildew throughout the Premises by notifying Landlord immediately if any evidence of water leak or excessive moisture, mold or mildew appears.