Long Narrow City Lot 50'x150'

[skifast13]

I have a grading question that involves the new construction of a detached garage. Existing home is dug into relatively steep grade (north to south) on the north side of the lot. There is a "step-down" running east-west that splits the lot and slopes further to the south. The new construction is to be placed at the southeast corner of the home on the lower tier of the property. There is a drive along the south lot line and a neighboring home directly on the south lot line (and subsequently, directly south of drive). Neighboring home already experiences massive foundation problems. There is another lot directly south of where the garage is proposed (about 75' deep in the east-west orientation), it joins the property at a perpedicular angle and the home is at least 50' to the south, however, don't want water drainage to be a problem for their yard either. First question is, how can water be directed as to not adversely affect the neighbor directly to the south with existing foundation problems? Second question is, how can gutter system on garage be arranged so as not to adversely affect perpendicularly abutted property's yard area? Thanks for bearing with rather lengthy and confusing description. Anything I'm missing here?

 

[KRSServices]

skifast,

Although your description is a little confusing, a couple more questions....

1) What kind of drainage system doe the property tie to...is it a ditch, curb and gutter or storm sewer configuration to the residence?

2) What do the local statutes and bylaws say about this matter?

Many building bylaws prohibit the drainage of water onto a neighbouring property and quite often specify that a swale or similar drainage channel be constructed. This is usually concurrent to new developments or building permits, as is this case.

KRS Services

http://www.krs-services.com

 

[Focht3]

Where is the site? (City, state only - for now.) What are the soil conditions?

Please describe the "massive" foundation problems experienced by the neighboring home -



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[SirAl]

helloskifast13

Just a few questions to help me better understand your site:

1)Please describe the "step-down" feature. Retaining wall? If so, what height? If not, describe the geometry.

2)how much relief from north property line to south property line across your lot?

3)Your description of the south lot line is confusing. The 'drive' at the south edge of the lot that you refer to, is this a municipal street accessing the residential area, a back lane, or is it a private access to your house? (I currently picture a back lane.) I take it that you can currently park your vehicles below the "step-down". Where is the front street relative to your lot?

I appreciate the fact that you are considering the potential influence of your lot drainage upon your neighbors. It wouldn't hurt to discuss your plans with them to determine if they have any concerns. With that said, KRSServices offers a sound suggestion to discuss your situation with the appropriate municipal authority (building inspector, development officer, etc.) I am reluctant to offer any suggestions without a better understanding of your lot, access, and neighboring lots.

 

[skifast13]

First of all, thank you for responding! Now to answer some of your questions:

Milwaukee, Wisconsin - storm sewer, MKE actually encourages homeowners to detach downspouts from the city's system because of deep tunnel backups during heavy rain - city will accept a percentage runoff from the property directly into the street - the soil type is relatively soft pack dirt/clay approximately two feet below surface, historical neighborhood setting of this grade has held up quite nicely throughout the years - neighbor to the south has hydrostatic pressure/crumbling walls and perfuse water damage (will replace northern foundation and place drain tiles at north elevation very soon, but not before something has to be done with the drive in question) - not a retaining wall between the step down, rather a steep grass slope of approximately 8/15 slope (.533) - ~3.5 feet of relief across the property (actually the laser level comes tomorrow so I don't exactly know that one) - municipal front street runs north/south and to the west of the lot and the drive in question is actually a private access with curbcut and two cars can comfortably be parked on the drive.

Here's one more brainbuster that I thought of this evening: The drive will be historically correct in that it will be constructed of pavers or cobblestones (full or two tracks in nature). What about running some sort of drain system underneath the cobblestones and past the west elevation of the neighbor to the south?

 

[Grouser]

skifast13
A couple more questions. Is there a curb inlet on the street in front of your property? Does your street/area have storm sewers or only catch basins? How much fall is there from the east (rear) of your lot to the west (front)? Is the frost depth approx. 42 inches?

 

[skifast13]

Thanks again for taking a look at this thread. Here are some more answers. No curb inlet, street has storm sewer (one) at the bottom of the hill, the east/west fall is negligible and the frost depth that you specified is correct.

 

[Grouser]

skifast13

I suggest building a six inch high clay berm along the south property line. You may, at additional expense, bury some impervious sheeting (capping the berm) also or in lieu of the clay. The berm can be hidden by landscape planting (don't puncture the sheeting). This should control the north to south surface flow. Whether it will flow east or west is another question. Any considerations for easterly flow? You could put in some dry wells or subsurface storage basins but it would be more expensive. Frost heave may be a problem with these methods.

How many lots to the bottom of the hill? Can you and your down-slope neighbors construct a 4"-6" storm sewer to convey this water to the street with the storm drain? Roof leaders could be connected to it and yard drains as well. Adequate provisions for clean-outs would have to be provided. Muni permitting is likely. Have you contacted your local governmental rep to see if funds are available for storm drain improvements?

Good luck.

 

[SirAl]

skifast13

Thank you for the additional information. I have a much better picture of your lot and neighboring properties.

First, a logistics consideration: You indicated that your neighbor to the south will be undertaking foundation and drainage remediation...'but not before something has to be done with the drive in question'. If his foundation is abutting the driveway, a portion of the driveway will be affected by his work. It would be logical to delay the grading/drainage improvement work on your driveway until your neighbor's subsurface work is completed.

My first instict would be to direct the surface drainage from your lot onto the front street if you are permitted to do so by the local authorities. This could be done with a swale or a curb along the south edge of your private drive. You may require some lot grading to provide for positive relief between your garage and the street. (Be sure to construct your garage pad above the adjacent street to the west).

Failing that, I'm afraid that I can't offer any further practical alternatives. In my neck of the woods, residential lot storm water retention is not a requirement. As such, I am not familiar with practices or necessary containment volumes in this regard. I personally don't like the idea of directing lot run-off onto adjacent residential lots. Guidance from a local municipal engineer could prove valuable.

 

[skifast13]

Thanks again for everything folks. This was pretty helpful in establishing some important points for my particular job. I've decided to take a few things into immediate consideration: first, I will skim some soil from the northern tier and use it as swale for the southern lot line and then build up the garage zone slightly higher than the rest of the lower southern portion just to the east of the southern neighbor's property line. Thus, she won't get nearly the run off that she was getting previous to this grading project. I'm holding off on the drive portion of the project so that when she does decide to work on her foundation, she has free reign to rip up the drive and replace. I will route rainwater from the garage roof by directing both gutter downspouts north of the southern lot line 5' and direct them parallel in the north/south orientation so that the rainwater does not fall south of my lot. If there are drainage problems in the future, I have a pass-through overhead door on the back of the proposed garage (east elevation) so that I can get machinery onto the property to take it to the "next level." Hopefully, it will not have to come to this as a catch basin will add quite a bit more monetarily to this project. Thanks again!