You could burry the drain under some of the rock but you must put landscape fabric over the top to keep it from getting clogged by the rocks or dirt. 

But beyond who should pay is actually the issue of whether or not there is a problem or if it's a fabrication.

Clean the back of the carpet with a good bleach solution (don't get it on the fabric), clean the floor, and plan on putting your own vapor barrier over the floor at some point in the future (i.e some type of solid vinyl floating floor or similar).

Set some traps with poison, keep them filled all the time, mice problem will be solved.Did your pest guy find signs of mice, do you think your tenants may be looking for a way to justify breaking their lease for other reasons.IT is not unusual for tenants to fabricate problems prior to a planed midnight run.

You could also have a carpenter fabricate something for you as was mentioned above. 

.$50/-55sf = formica in rental units built close to the $52-55/sf$55-60 = Granit Counters or 2cm Granite plus custom marble counters in bathrooms unless Buyer selects full granite option if the have time to do so prior to fabrication.25 year 3 tab roof shingles/ 5:12 pitch/ brick fronts & mailbox with rear and side elevations hardi-siding/  9' plate line/ vaulted to 11' in great room areas and kitchen (open concept plans)/ Stained Concrete Floors/ Pre-Fab Cabinets/ Chrome Fixtures/ Wall have batt insulation/ Attic blow in insulation/ std vinyl windows/ Fiberglass shower tub units and also a garden tub with wall tile/ all Chrome appliances but no refer/  std 3.25 base/ std doors - nothing upgraded/ no fireplaces/ 10x15' rear patios/ 2 car garage/ traditional style homes....Land cost here was cheaper when I first got into this market.  

Having spent a good deal of time traveling the world and having either lived in or traveled to many third-world and developing countries, I can say that you gain a whole new respect for just how fragile the whole social fabric is.  

However, when I got my hands on it via e-mail - it was clearly a lease they had hastily fabricated.

However, when I got my hands on it via e-mail - it was clearly a lease they had hastily fabricated.

Need recommendations on fabricators of exterior metal stairs for 2nd and 3rd floor egress.