Blog

Se alle vores blogs

Forskellen på højvandslukke og pumpebrønd

december 10, 2025

img:is([sizes=auto i],[sizes^="auto," i]){contain-intrinsic-size:3000px 1500px}:root{--wp-block-synced-color:#7a00df;--wp-block-synced-color--rgb:122,0,223;--wp-bound-block-color:var(--wp-block-synced-color);--wp-editor-canvas-background:#ddd;--wp-admin-theme-color:#007cba;--wp-admin-theme-color--rgb:0,124,186;--wp-admin-theme-color-darker-10:#006ba1;--wp-admin-theme-color-darker-10--rgb:0,107,160.5;--wp-admin-theme-color-darker-20:#005a87;--wp-admin-theme-color-darker-20--rgb:0,90,135;--wp-admin-border-width-focus:2px}@media (min-resolution:192dpi){:root{--wp-admin-border-width-focus:1.5px}}.wp-element-button{cursor:pointer}:root .has-very-light-gray-background-color{background-color:#eee}:root .has-very-dark-gray-background-color{background-color:#313131}:root .has-very-light-gray-color{color:#eee}:root .has-very-dark-gray-color{color:#313131}:root .has-vivid-green-cyan-to-vivid-cyan-blue-gradient-background{background:linear-gradient(135deg,#00d084,#0693e3)}:root .has-purple-crush-gradient-background{background:linear-gradient(135deg,#34e2e4,#4721fb 50%,#ab1dfe)}:root .has-hazy-dawn-gradient-background{background:linear-gradient(135deg,#faaca8,#dad0ec)}:root .has-subdued-olive-gradient-background{background:linear-gradient(135deg,#fafae1,#67a671)}:root .has-atomic-cream-gradient-background{background:linear-gradient(135deg,#fdd79a,#004a59)}:root .has-nightshade-gradient-background{background:linear-gradient(135deg,#330968,#31cdcf)}:root .has-midnight-gradient-background{background:linear-gradient(135deg,#020381,#2874fc)}:root{--wp--preset--font-size--normal:16px;--wp--preset--font-size--huge:42px}.has-regular-font-size{font-size:1em}.has-larger-font-size{font-size:2.625em}.has-normal-font-size{font-size:var(--wp--preset--font-size--normal)}.has-huge-font-size{font-size:var(--wp--preset--font-size--huge)}.has-text-align-center{text-align:center}.has-text-align-left{text-align:left}.has-text-align-right{text-align:right}.has-fit-text{white-space:nowrap !important}#end-resizable-editor-section{display:none}.aligncenter{clear:both}.items-justified-left{justify-content:flex-start}.items-justified-center{justify-content:center}.items-justified-right{justify-content:flex-end}.items-justified-space-between{justify-content:space-between}.screen-reader-text{border:0;clip-path:inset(50%);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px;word-wrap:normal !important}.screen-reader-text:focus{background-color:#ddd;clip-path:none;color:#444;display:block;font-size:1em;height:auto;left:5px;line-height:normal;padding:15px 23px 14px;text-decoration:none;top:5px;width:auto;z-index:100000}html :where(.has-border-color){border-style:solid}html :where([style*=border-top-color]){border-top-style:solid}html :where([style*=border-right-color]){border-right-style:solid}html :where([style*=border-bottom-color]){border-bottom-style:solid}html :where([style*=border-left-color]){border-left-style:solid}html :where([style*=border-width]){border-style:solid}html :where([style*=border-top-width]){border-top-style:solid}html :where([style*=border-right-width]){border-right-style:solid}html :where([style*=border-bottom-width]){border-bottom-style:solid}html :where([style*=border-left-width]){border-left-style:solid}html :where(img[class*=wp-image-]){height:auto;max-width:100%}:where(figure){margin:0 0 1em}html :where(.is-position-sticky){--wp-admin--admin-bar--position-offset:var(--wp-admin--admin-bar--height,0px)}@media screen and (max-width:600px){html :where(.is-position-sticky){--wp-admin--admin-bar--position-offset:0px}}:root{--wp--preset--aspect-ratio--square:1;--wp--preset--aspect-ratio--4-3:4/3;--wp--preset--aspect-ratio--3-4:3/4;--wp--preset--aspect-ratio--3-2:3/2;--wp--preset--aspect-ratio--2-3:2/3;--wp--preset--aspect-ratio--16-9:16/9;--wp--preset--aspect-ratio--9-16:9/16;--wp--preset--color--black:#000;--wp--preset--color--cyan-bluish-gray:#abb8c3;--wp--preset--color--white:#fff;--wp--preset--color--pale-pink:#f78da7;--wp--preset--color--vivid-red:#cf2e2e;--wp--preset--color--luminous-vivid-orange:#ff6900;--wp--preset--color--luminous-vivid-amber:#fcb900;--wp--preset--color--light-green-cyan:#7bdcb5;--wp--preset--color--vivid-green-cyan:#00d084;--wp--preset--color--pale-cyan-blue:#8ed1fc;--wp--preset--color--vivid-cyan-blue:#0693e3;--wp--preset--color--vivid-purple:#9b51e0;--wp--preset--color--metallic-red:#b02b2c;--wp--preset--color--maximum-yellow-red:#edae44;--wp--preset--color--yellow-sun:#ee2;--wp--preset--color--palm-leaf:#83a846;--wp--preset--color--aero:#7bb0e7;--wp--preset--color--old-lavender:#745f7e;--wp--preset--color--steel-teal:#5f8789;--wp--preset--color--raspberry-pink:#d65799;--wp--preset--color--medium-turquoise:#4ecac2;--wp--preset--gradient--vivid-cyan-blue-to-vivid-purple:linear-gradient(135deg,#0693e3 0%,#9b51e0 100%);--wp--preset--gradient--light-green-cyan-to-vivid-green-cyan:linear-gradient(135deg,#7adcb4 0%,#00d082 100%);--wp--preset--gradient--luminous-vivid-amber-to-luminous-vivid-orange:linear-gradient(135deg,#fcb900 0%,#ff6900 100%);--wp--preset--gradient--luminous-vivid-orange-to-vivid-red:linear-gradient(135deg,#ff6900 0%,#cf2e2e 100%);--wp--preset--gradient--very-light-gray-to-cyan-bluish-gray:linear-gradient(135deg,#eee 0%,#a9b8c3 100%);--wp--preset--gradient--cool-to-warm-spectrum:linear-gradient(135deg,#4aeadc 0%,#9778d1 20%,#cf2aba 40%,#ee2c82 60%,#fb6962 80%,#fef84c 100%);--wp--preset--gradient--blush-light-purple:linear-gradient(135deg,#ffceec 0%,#9896f0 100%);--wp--preset--gradient--blush-bordeaux:linear-gradient(135deg,#fecda5 0%,#fe2d2d 50%,#6b003e 100%);--wp--preset--gradient--luminous-dusk:linear-gradient(135deg,#ffcb70 0%,#c751c0 50%,#4158d0 100%);--wp--preset--gradient--pale-ocean:linear-gradient(135deg,#fff5cb 0%,#b6e3d4 50%,#33a7b5 100%);--wp--preset--gradient--electric-grass:linear-gradient(135deg,#caf880 0%,#71ce7e 100%);--wp--preset--gradient--midnight:linear-gradient(135deg,#020381 0%,#2874fc 100%);--wp--preset--font-size--small:1rem;--wp--preset--font-size--medium:1.125rem;--wp--preset--font-size--large:1.75rem;--wp--preset--font-size--x-large:clamp(1.75rem,3vw,2.25rem);--wp--preset--spacing--20:.44rem;--wp--preset--spacing--30:.67rem;--wp--preset--spacing--40:1rem;--wp--preset--spacing--50:1.5rem;--wp--preset--spacing--60:2.25rem;--wp--preset--spacing--70:3.38rem;--wp--preset--spacing--80:5.06rem;--wp--preset--shadow--natural:6px 6px 9px rgba(0,0,0,.2);--wp--preset--shadow--deep:12px 12px 50px rgba(0,0,0,.4);--wp--preset--shadow--sharp:6px 6px 0px rgba(0,0,0,.2);--wp--preset--shadow--outlined:6px 6px 0px -3px #fff,6px 6px #000;--wp--preset--shadow--crisp:6px 6px 0px #000}:root{--wp--style--global--content-size:800px;--wp--style--global--wide-size:1130px}:where(body){margin:0}.wp-site-blocks > .alignleft{float:left;margin-right:2em}.wp-site-blocks > .alignright{float:right;margin-left:2em}.wp-site-blocks > .aligncenter{justify-content:center;margin-left:auto;margin-right:auto}:where(.is-layout-flex){gap:.5em}:where(.is-layout-grid){gap:.5em}.is-layout-flow > .alignleft{float:left;margin-inline-start:0;margin-inline-end:2em}.is-layout-flow > .alignright{float:right;margin-inline-start:2em;margin-inline-end:0}.is-layout-flow > .aligncenter{margin-left:auto !important;margin-right:auto !important}.is-layout-constrained > .alignleft{float:left;margin-inline-start:0;margin-inline-end:2em}.is-layout-constrained > .alignright{float:right;margin-inline-start:2em;margin-inline-end:0}.is-layout-constrained > .aligncenter{margin-left:auto !important;margin-right:auto !important}.is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width:var(--wp--style--global--content-size);margin-left:auto !important;margin-right:auto !important}.is-layout-constrained > .alignwide{max-width:var(--wp--style--global--wide-size)}body .is-layout-flex{display:flex}.is-layout-flex{flex-wrap:wrap;align-items:center}.is-layout-flex > :is(*, div){margin:0}body .is-layout-grid{display:grid}.is-layout-grid > :is(*, div){margin:0}body{padding-top:0px;padding-right:0px;padding-bottom:0px;padding-left:0px}a:where(:not(.wp-element-button)){text-decoration:underline}:root :where(.wp-element-button, .wp-block-button__link){background-color:#32373c;border-width:0;color:#fff;font-family:inherit;font-size:inherit;font-style:inherit;font-weight:inherit;letter-spacing:inherit;line-height:inherit;padding-top:calc(.667em + 2px);padding-right:calc(1.333em + 2px);padding-bottom:calc(.667em + 2px);padding-left:calc(1.333em + 2px);text-decoration:none;text-transform:inherit}.has-black-color{color:var(--wp--preset--color--black) !important}.has-cyan-bluish-gray-color{color:var(--wp--preset--color--cyan-bluish-gray) !important}.has-white-color{color:var(--wp--preset--color--white) !important}.has-pale-pink-color{color:var(--wp--preset--color--pale-pink) !important}.has-vivid-red-color{color:var(--wp--preset--color--vivid-red) !important}.has-luminous-vivid-orange-color{color:var(--wp--preset--color--luminous-vivid-orange) !important}.has-luminous-vivid-amber-color{color:var(--wp--preset--color--luminous-vivid-amber) !important}.has-light-green-cyan-color{color:var(--wp--preset--color--light-green-cyan) !important}.has-vivid-green-cyan-color{color:var(--wp--preset--color--vivid-green-cyan) !important}.has-pale-cyan-blue-color{color:var(--wp--preset--color--pale-cyan-blue) !important}.has-vivid-cyan-blue-color{color:var(--wp--preset--color--vivid-cyan-blue) !important}.has-vivid-purple-color{color:var(--wp--preset--color--vivid-purple) !important}.has-metallic-red-color{color:var(--wp--preset--color--metallic-red) !important}.has-maximum-yellow-red-color{color:var(--wp--preset--color--maximum-yellow-red) !important}.has-yellow-sun-color{color:var(--wp--preset--color--yellow-sun) !important}.has-palm-leaf-color{color:var(--wp--preset--color--palm-leaf) !important}.has-aero-color{color:var(--wp--preset--color--aero) !important}.has-old-lavender-color{color:var(--wp--preset--color--old-lavender) !important}.has-steel-teal-color{color:var(--wp--preset--color--steel-teal) !important}.has-raspberry-pink-color{color:var(--wp--preset--color--raspberry-pink) !important}.has-medium-turquoise-color{color:var(--wp--preset--color--medium-turquoise) !important}.has-black-background-color{background-color:var(--wp--preset--color--black) !important}.has-cyan-bluish-gray-background-color{background-color:var(--wp--preset--color--cyan-bluish-gray) !important}.has-white-background-color{background-color:var(--wp--preset--color--white) !important}.has-pale-pink-background-color{background-color:var(--wp--preset--color--pale-pink) !important}.has-vivid-red-background-color{background-color:var(--wp--preset--color--vivid-red) !important}.has-luminous-vivid-orange-background-color{background-color:var(--wp--preset--color--luminous-vivid-orange) !important}.has-luminous-vivid-amber-background-color{background-color:var(--wp--preset--color--luminous-vivid-amber) !important}.has-light-green-cyan-background-color{background-color:var(--wp--preset--color--light-green-cyan) !important}.has-vivid-green-cyan-background-color{background-color:var(--wp--preset--color--vivid-green-cyan) !important}.has-pale-cyan-blue-background-color{background-color:var(--wp--preset--color--pale-cyan-blue) !important}.has-vivid-cyan-blue-background-color{background-color:var(--wp--preset--color--vivid-cyan-blue) !important}.has-vivid-purple-background-color{background-color:var(--wp--preset--color--vivid-purple) !important}.has-metallic-red-background-color{background-color:var(--wp--preset--color--metallic-red) !important}.has-maximum-yellow-red-background-color{background-color:var(--wp--preset--color--maximum-yellow-red) !important}.has-yellow-sun-background-color{background-color:var(--wp--preset--color--yellow-sun) !important}.has-palm-leaf-background-color{background-color:var(--wp--preset--color--palm-leaf) !important}.has-aero-background-color{background-color:var(--wp--preset--color--aero) !important}.has-old-lavender-background-color{background-color:var(--wp--preset--color--old-lavender) !important}.has-steel-teal-background-color{background-color:var(--wp--preset--color--steel-teal) !important}.has-raspberry-pink-background-color{background-color:var(--wp--preset--color--raspberry-pink) !important}.has-medium-turquoise-background-color{background-color:var(--wp--preset--color--medium-turquoise) !important}.has-black-border-color{border-color:var(--wp--preset--color--black) !important}.has-cyan-bluish-gray-border-color{border-color:var(--wp--preset--color--cyan-bluish-gray) !important}.has-white-border-color{border-color:var(--wp--preset--color--white) !important}.has-pale-pink-border-color{border-color:var(--wp--preset--color--pale-pink) !important}.has-vivid-red-border-color{border-color:var(--wp--preset--color--vivid-red) !important}.has-luminous-vivid-orange-border-color{border-color:var(--wp--preset--color--luminous-vivid-orange) !important}.has-luminous-vivid-amber-border-color{border-color:var(--wp--preset--color--luminous-vivid-amber) !important}.has-light-green-cyan-border-color{border-color:var(--wp--preset--color--light-green-cyan) !important}.has-vivid-green-cyan-border-color{border-color:var(--wp--preset--color--vivid-green-cyan) !important}.has-pale-cyan-blue-border-color{border-color:var(--wp--preset--color--pale-cyan-blue) !important}.has-vivid-cyan-blue-border-color{border-color:var(--wp--preset--color--vivid-cyan-blue) !important}.has-vivid-purple-border-color{border-color:var(--wp--preset--color--vivid-purple) !important}.has-metallic-red-border-color{border-color:var(--wp--preset--color--metallic-red) !important}.has-maximum-yellow-red-border-color{border-color:var(--wp--preset--color--maximum-yellow-red) !important}.has-yellow-sun-border-color{border-color:var(--wp--preset--color--yellow-sun) !important}.has-palm-leaf-border-color{border-color:var(--wp--preset--color--palm-leaf) !important}.has-aero-border-color{border-color:var(--wp--preset--color--aero) !important}.has-old-lavender-border-color{border-color:var(--wp--preset--color--old-lavender) !important}.has-steel-teal-border-color{border-color:var(--wp--preset--color--steel-teal) !important}.has-raspberry-pink-border-color{border-color:var(--wp--preset--color--raspberry-pink) !important}.has-medium-turquoise-border-color{border-color:var(--wp--preset--color--medium-turquoise) !important}.has-vivid-cyan-blue-to-vivid-purple-gradient-background{background:var(--wp--preset--gradient--vivid-cyan-blue-to-vivid-purple) !important}.has-light-green-cyan-to-vivid-green-cyan-gradient-background{background:var(--wp--preset--gradient--light-green-cyan-to-vivid-green-cyan) !important}.has-luminous-vivid-amber-to-luminous-vivid-orange-gradient-background{background:var(--wp--preset--gradient--luminous-vivid-amber-to-luminous-vivid-orange) !important}.has-luminous-vivid-orange-to-vivid-red-gradient-background{background:var(--wp--preset--gradient--luminous-vivid-orange-to-vivid-red) !important}.has-very-light-gray-to-cyan-bluish-gray-gradient-background{background:var(--wp--preset--gradient--very-light-gray-to-cyan-bluish-gray) !important}.has-cool-to-warm-spectrum-gradient-background{background:var(--wp--preset--gradient--cool-to-warm-spectrum) !important}.has-blush-light-purple-gradient-background{background:var(--wp--preset--gradient--blush-light-purple) !important}.has-blush-bordeaux-gradient-background{background:var(--wp--preset--gradient--blush-bordeaux) !important}.has-luminous-dusk-gradient-background{background:var(--wp--preset--gradient--luminous-dusk) !important}.has-pale-ocean-gradient-background{background:var(--wp--preset--gradient--pale-ocean) !important}.has-electric-grass-gradient-background{background:var(--wp--preset--gradient--electric-grass) !important}.has-midnight-gradient-background{background:var(--wp--preset--gradient--midnight) !important}.has-small-font-size{font-size:var(--wp--preset--font-size--small) !important}.has-medium-font-size{font-size:var(--wp--preset--font-size--medium) !important}.has-large-font-size{font-size:var(--wp--preset--font-size--large) !important}.has-x-large-font-size{font-size:var(--wp--preset--font-size--x-large) !important}#top .avia-font-entypo-fontello-enfold,body .avia-font-entypo-fontello-enfold,html body [data-av_iconfont='entypo-fontello-enfold']:before{font-family:"entypo-fontello-enfold"}#top .avia-font-entypo-fontello,body .avia-font-entypo-fontello,html body [data-av_iconfont='entypo-fontello']:before{font-family:"entypo-fontello"}#top .avia-font-flaticon_hndvrkeren,body .avia-font-flaticon_hndvrkeren,html body [data-av_iconfont='flaticon_hndvrkeren']:before{font-family:"flaticon_hndvrkeren"}#top .avia-font-flaticon_generelle_ikoner,body .avia-font-flaticon_generelle_ikoner,html body [data-av_iconfont='flaticon_generelle_ikoner']:before{font-family:"flaticon_generelle_ikoner"}.flex_column.av-dfw3f5-5b477e241ab8c63a0916c25b46055576{border-radius:0px 0px 0px 0px;padding:0px 0px 0px 0px}#top .av_textblock_section.av-5072d-7-c39df9e656608f329d48789873d1d539 .avia_textblock{font-size:20px}.flex_column.av-ca86i9-2d31ad0d0d307ea99ce6f63f5b85949d{border-radius:0px 0px 0px 0px;padding:0px 0px 0px 0px}#top .av_textblock_section.av-a4bm01-a5655fd0d1500ba4d2f458ff571c7ae7 .avia_textblock{font-size:20px}.flex_column.av-8rfhsx-90bb96997148c596bf5b7f9a9a2e66c2{border-radius:0px 0px 0px 0px;padding:0px 0px 0px 0px}#top .av_textblock_section.av-m7ak4t4e-8aa32de5a0d00353294a501f0c3e78b5 .avia_textblock{font-size:20px}#top .hr.hr-invisible.av-898hk1-aa4c6e470c0a33bb818f74803609d47a{height:5px}.flex_column.av-6fsy69-8b9ae5f6846035e913cb580b186d6449{border-radius:0px 0px 0px 0px;padding:0px 0px 0px 0px}#top .av_textblock_section.av-m1hitao0-3e639b95cc11eb814a94be711d50683e .avia_textblock{font-size:20px}#top .hr.hr-invisible.av-dbxqp-d0466bef6dc3e4fb287b38fea5a45e96{height:10px}.flex_cell.av-f2gnx-d31ef9dbca5bba2630b16d8fa4dc8f8f{vertical-align:top;background-color:#fff}.responsive #top #wrap_all .flex_cell.av-f2gnx-d31ef9dbca5bba2630b16d8fa4dc8f8f{padding:8px 8px 8px 8px !important}.av_font_icon.av-kcvsrm3d-9e1ece5656d0897cc391a658f34b3c38{color:#f93;border-color:#f93}.avia-svg-icon.av-kcvsrm3d-9e1ece5656d0897cc391a658f34b3c38 svg:first-child{stroke:#f93;fill:#f93}.av_font_icon.av-kcvsrm3d-9e1ece5656d0897cc391a658f34b3c38 .av-icon-char{font-size:30px;line-height:30px}#top .av_textblock_section.av-kcvsuvzu-a518584288e351de507dd4a72ca35cbf .avia_textblock{font-size:11px;color:#333}#top .hr.hr-invisible.av-kettp41i-22cd862696b7e8d8806468242c236c69{height:10px}.flex_cell.av-aozol-293d8c5b6ace0c1f12fa08ee90d2177a{vertical-align:top;background-color:#fff}.responsive #top #wrap_all .flex_cell.av-aozol-293d8c5b6ace0c1f12fa08ee90d2177a{padding:8px 8px 8px 8px !important}.av_font_icon.av-kcvsrm3d-10-6952f9c3e52cb3aa9a4e6ca0ff88f693{color:#f93;border-color:#f93}.avia-svg-icon.av-kcvsrm3d-10-6952f9c3e52cb3aa9a4e6ca0ff88f693 svg:first-child{stroke:#f93;fill:#f93}.av_font_icon.av-kcvsrm3d-10-6952f9c3e52cb3aa9a4e6ca0ff88f693 .av-icon-char{font-size:30px;line-height:30px}#top .av_textblock_section.av-kcvsuvzu-9-c8da762ff0e69a23b52e14aba397754d .avia_textblock{font-size:11px;color:#333}#top .hr.hr-invisible.av-kettp41i-8-c3fa36432fb1423796747330e498ab4c{height:10px}.flex_cell.av-a5qs5-0f5f37f8d1f60e55df9740fb357a2cc1{vertical-align:top;background-color:#fff}.responsive #top #wrap_all .flex_cell.av-a5qs5-0f5f37f8d1f60e55df9740fb357a2cc1{padding:8px 8px 8px 8px !important}.flex_column.av-kfy0q7r0-1946ca38bc6439256d8ccf9964e57267{border-radius:0px 0px 0px 0px;padding:0px 0px 0px 0px}.av_font_icon.av-kcvsrm3d-7-2147f828eec8b2bfbed4339d03ad7d4d{color:#f93;border-color:#f93}.avia-svg-icon.av-kcvsrm3d-7-2147f828eec8b2bfbed4339d03ad7d4d svg:first-child{stroke:#f93;fill:#f93}.av_font_icon.av-kcvsrm3d-7-2147f828eec8b2bfbed4339d03ad7d4d .av-icon-char{font-size:30px;line-height:30px}#top .hr.hr-invisible.av-khq3agnr-8798f42adb2a7871338e126029d1e4e2{height:2px}#top .av_textblock_section.av-kcvsuvzu-6-8602f68786d66339971d5610c47e92b5 .avia_textblock{font-size:11px;color:#333}#top .hr.hr-invisible.av-kettp41i-5-f0effe4b462adb728992fa71b8670a4f{height:10px}.flex_cell.av-a5qs5-4-7fb9c4fe817d05b82462cfafbf5789a5{vertical-align:top;background-color:#002f21}.responsive #top #wrap_all .flex_cell.av-a5qs5-4-7fb9c4fe817d05b82462cfafbf5789a5{padding:8px 8px 8px 8px !important}.av_font_icon.av-kcvsrm3d-3-5032c632976293df6e2e801f8ff0d7c1{color:#fff;border-color:#fff}.avia-svg-icon.av-kcvsrm3d-3-5032c632976293df6e2e801f8ff0d7c1 svg:first-child{stroke:#fff;fill:#fff}.av_font_icon.av-kcvsrm3d-3-5032c632976293df6e2e801f8ff0d7c1 .av-icon-char{font-size:30px;line-height:30px}#top .av_textblock_section.av-kcvsuvzu-2-b6af9f250c0aef08f684b13cd26baf6e .avia_textblock{font-size:11px;color:#fff}#top .hr.hr-invisible.av-kettp41i-1-7b4853731d3f529977c4bd71e0e65f5c{height:10px}

Blog

Hvad er en TV-inspektion?

Forskellen på højvandslukke og pumpebrønd

Hvem må lave omfangsdræn?