I disagree with the term compacted, but that's mostly semantics. What you're looking for is soil like a sponge (soft when wet and firm (hard??) when dry). If your soil is hard when dry, that's normal. If it is hard when wet, it's not necessarily compacted. Compacted is when the soil was once wet and somehow got the air driven out of it by animals or by repeated machine impact. When that happens the soil loses air and air passageways. Since the beneficial fungi need air to live, they die. My observation is that soil fungi are the natural critters that soften soil. If you run a soaker hose on very very slow for a week at a time, you can reestablish the soil biology. Very slow means at the faucet it only drips out. After a week of soaking, move the hose to a new dry spot adjacent to the current wet spot and let it run. After covering the entire yard, repeat. After covering the entire yard a second time, repeat one last time. This technique only costs you for the water. One thing to keep in mind is that you will have to continue watering regularly throughout the soaking process.

I'd vote for something direct or indirect. I can't think of another way to do it. Direct would be a probe of some sort that you stick into the ground and pump your fert and water into. Indirect would be some sort of traditional irrigation. I think the most efficient would be a slow or drip irrigation that would soak into the ground rather than running off. Any number of ways to accomplish both. PVC appears simple but the bore sounds large. The commercial root feeders have an oversized needle type applicator. Municipalities often put bags that hold I'm guessing 5-10 gallons of water around trees that release the fluid over days I assume. I'm not sure if they can adjust the flow rate or if it is fixed by the bag material. You can easily purchase a drip irrigation system but you have to put up with semi-permanent tubing to the plants.

merdena, yes! I say this from my own experience. In other words, 'if I could do it, anyone can.' I had two advantages. I worked in a hardware store and I did 18 hours of "irrigation school". The most important thing I learned in school was to identify and name correctly the many and various fittings. My first investment was in a can each of cleaner and glue, some pipe and fittings and a hacksaw. My first successful project was extending the water supply to our washing machine. It had to be removable to leave the original fixture intact when we left the apartment. PVC is a particular joy to work with because if you make a mistake, you can use the hacksaw to get back to the drawing board. I practised aligning fittings (without glue) to make piping go where I wanted. Then I would glue the project, test it and cover it up. Two habits I formed were to always use colored glue so that I could spot a joint that was not glued and to always use teflon tape on threaded fittings. Hardware stores have these free booklets which will walk you through the project from beginning to end. You yurself will not be able to resist getting into the act; there are so many spinoffs! Like making PVC furniture, plant supports, lightweight shelving and (clothing) racks etc. etc.

I think your landscape architect is wrong. I would thoroughly water everything daily for the first week, every two days the second week, then taper off to twice per week through the hot part of the first summer. Keep the soil reasonably moist until it freezes the first fall. The second summer I would water thoroughly only if you encounter dry spells more than a week long. After that you should be fine. I wouldn't spend any money to install an irrigation system. You can use hose-end sprinklers and water without too much effort the first year or two and it will save lots of money.