As defined by DPAP, "a split purchase is the “intentional” breaking down of a known requirement to stay within the cardholder’s single purchase limit to avoid sending the requirement to the contracting office for award. Split purchases include: splitting requirements among merchants; splitting requirements among cardholders and splitting requirements over several days. "
In your scenario, one card was used to buy materials for different projects, with different billing codes, to be used in different locations, and the materials were ordered at different times. You had a series of unrelated known needs on the same invoice during the same billing cycle. Some of the items when combined were still under the $3,500 micro-purchase threshold. That does not meet the definition of an intentional split purchase.
DPAP also states "Approving/Billing Officials and Cardholders should contact the contracting office when they identify repetitive requirements for supplies, services or construction requirements increasing to levels that will surpass the CHs single purchase threshold." While this question does not seem like a split purchase designed to defeat the threshold, the buyer should attempt to identify the amount of similar items they are ordering, or will be ordering over a period of time to avoid the appearance of splitting. I would also recommend your contracting office establish a Blanket Purchase Agreements (BPAs) that will allow the CH to place orders at a higher level than the micro-purchase thresholds to avoid splitting requirements while negotiating better pricing and delivery for the best interest of the Government. For more government credit card policy, see the following DPAP documents: http://www.acq.osd.mil/dpap/pdi/pc/policy_documents.html