I have been asked to remove 15 red oaks (8 to 15 inch DBH) and 3, 90 foot white pines on a 1/4 acre property in a suburban neighborhood of Boston. The cient is on the uphill side of a 15 -2 5 degree slope of well drained, stoney soil on top of ledge rock. The down hill neighbor is worried that the tree removal will increase water coming onto his property and flood his basement (which happens anyway since he installed an in-ground pool). My client intends grade the cleared area and landscape with lawn and shrubs (which, in my opinion should stem the flow of water). There is no standing water on the property and runoff is a problem only after heavy or prolonged rain. There is a drainage ditch between the two propoprties that is effective for normal rain fall.

Will the tree removal increase the water runoff on the down hill property and compound the flooding problem? Any advice or direction here would be appreciated. This could get messy.

Thanks, Dave H.

Reply to post by Dave H, on October 14, 1998 at 18:57:00:

It seems to me that during rainstorms with wind, the volume of water that is stopped or collected would be reduced. During rains that are not accompanied by winds, there wouldn't be much of a change in volume.

I do think that the speed with which water runs off your client's property would increase with the absence of the plant's surface area slowing the movement of the moisture.

The trees themselves may not be as important an issue as the excavation and grading that would theoretically take place, especially during the transition period between the existing landscape design and the planned revamp.

Just my two cents worth,
KWK

Reply to post by Dave H, on October 14, 1998 at 18:57:00:

Could get messy because of the mud or the litigation? This is really an engineering question and outside the arborist's competence or expertise. The owner should be concerned about future litigation and the arborist could be named (don't they always name everyone?). Check your insurance policy and see if you're covered for future offsite liability (flooding)on completed work. Document current conditions and causes (neighbor's pool: who says it caused the problem?). If it's not a Pandora's box talk to local/state Environmental Protection agencies, they may have expertise. Are permits required for tree removal? Are permits required for grading and stump removal? Are silt fencing, hay bales, etc. required during project? Are you responsible fopr any oif this? An awful lot of this is owner's responsibility, but if owner ignores it you could be at risk. CROSS THE T's AND DOT THE I's.

Reply to post by Dave H, on October 14, 1998 at 18:57:00:

I agree with Scott, in that you have to do a little homework first.

If the concern is the trees absorbing moisture- it won't happen. The soil holds a tremendous amount of moisture, and the transpiration by trees will not have any significant effect on short-term flooding. Erosion is a concern, but this is less than a 2 to 1 slope- not exactly steep. Restoring cover will probably be effective in slope stabilization.

The issues here really are the capacity of the soil to absorb and drain the water. The drainage ditch may be sufficient, or perhaps your client (uphill neighbor) may want to consider additional drainage to protect his neighbor. The problem of course is where will the water go, even in the drain. I suggest contacting the local municipality (city, county, state, etc) for guidelines, or consulting with a qualified soils engineer to address the drainage problems. A quick look and a letter may be all that's needed to clear the job.

Russ Carlson

Reply to post by Russ Carlson, on October 14, 1998 at 18:57:00:

Dave, I would be very concerned about the reduced penetration of rain (and irregation) into the soil after heavy equipment has scraped, compacted, pushed, compacted, and final graded,and compacted again. Where will all the downpour go that used to enter the undesturbed topsoil? That topsoil acted like a detention area.
Fred

Reply to post by Fred J Robinson, on October 19, 1998 at 19:28:56:

Thank you all for the input and advice. It seems there is no easy solution to this problem. I have talked to a couple of forest hydrologists and have gotten pretty much the same response. There are too many factors to consider such as increased runoff,throughfall of the water, the depth of the actual water movement, change of grade, etc... in other words, very site specific and probably in the realm of engineering rather than arboricutlure.

I may back off from this one. The client is also a friend and should understand.

Thanks again everyone

Dave H.