09-14-2020 Council Packet - Laserfiche WebLink

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July 20, 2020 page 35 a. Where a public storm sewer is accessible, the subdivider shall install storm sewer facilities; 1490 or, if no outlets are within a reasonable distance, adequate provision shall be made for the 1491 disposal of stormwaters, subject to the specifications of the city. However, in subdivisions 1492 containing lots less than 22,000 square feet in area and in business and industrial districts, 1493 underground storm sewer systems shall be constructed throughout the subdivisions and be 1494 conducted to an approved outfall. 1495 b. If a connection to a public storm sewer will be provided eventually, as determined by the 1496 city, the subdivider shall make arrangements for future stormwater disposal by a public 1497 utility system at the time the subdivision receives final approval. Provision for such 1498 connection shall be incorporated by inclusion in the performance bondBond required for the 1499 final subdivision. 1500 (3) Accommodation of upstream drainage areas. A culvert or other drainage facility shall in each 1501 case be large enough to accommodate potential runoff from its entire upstream drainage area, 1502 whether inside or outside the subdivision. The city shall determine the necessary size of the 1503 facility, based on the provisions of the construction standards and specifications assuming 1504 conditions of maximum potential watershed development permitted by chapter 78 and 1505 comprehensive municipal planCommunity Management Plan. 1506 (4) Effect on downstream drainage areas. The city shall also study the effect of each subdivisionplat 1507 on existing downstream drainage facilities outside the area of the subdivisionplat. City drainage 1508 studies, together with such other studies as shall be appropriate, shall serve as a guide to needed 1509 improvements. Where it is anticipated that the additional runoff incident to the development of 1510 the subdivisionplat will overload an existing downstream drainage facility, the city may withhold 1511 approval of the subdivisionplat until provision has been made for the improvement of the potential 1512 condition at the subdivider's expense and in such sum as the city shall determine. No 1513 subdivisionplat shall be approved unless adequate drainage will be provided to an adequate 1514 drainage watercourse or facility. 1515 (5) Floodplain areas. The city may, when it deems it necessary for the health, safety or welfare of 1516 the population of the area and necessary to the conservation of water, drainage and sanitary 1517 facilities, prohibit the subdivision of any portion of the property which lies within the floodplain 1518 of any stream, lake or drainage course. These floodplain areas shall be preserved from any and 1519 all destruction or damage resulting from clearing, grading or dumping of earth, waste material or 1520 stumps by the appropriate conservation easement. 1521 (c) Dedication of drainage easements. 1522 (1) General requirements. Where a subdivisionplat is traversed by a wetlands, swamp, watercourse, 1523 drainageway, channel or stream, there shall be provided a stormwater easement, conservation and 1524 flowage easement, or drainage right-of-way conforming substantially to the lines of such 1525 watercourse, and of such width and construction or both as will be adequate for the purpose. 1526 Wherever possible, it is desirable that the drainage be maintained by an open channel with 1527 landscaped banks and adequate width for maximum potential volume of flow. 1528 (2) Drainage easements. 1529 a. Where topography or other conditions are such as to make impractical the inclusion of 1530 drainage facilities within road rights-of-way, perpetual unobstructed easements of an 1531 appropriate width at least 15 feet in width for such drainage facilities shall be provided across 1532 property outside the road lines and with satisfactory access to a public roadway. Easements 1533 shall be indicated on the platn if subdivision is a plat. Drainage easements shall be carried 1534 from the road to a natural watercourse or to other drainage facilities. 1535